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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 19 Mar 2019 at 01:49 Created: 


WIKIPEDIA: Wolbachia is a genus of bacteria which "infects" (usually as intracellular symbionts) arthropod species, including a high proportion of insects, as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia infection. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70 percent of all insect species are estimated to be potential hosts. Wolbachia also harbor a temperate bacteriophage called WO. Comparative sequence analyses of bacteriophage WO offer some of the most compelling examples of large-scale horizontal gene transfer between Wolbachia coinfections in the same host. It is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that were previously considered highly stable or prone to loss of genes overtime. Outside of insects, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heartworms in dogs. Not only are these disease-causing filarial worms infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally results in either death or sterility of the nematode.

Created with PubMed® Query: wolbachia NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-03-14

Balaji S, Jayachandran S, SR Prabagaran (2019)

Evidence for the natural occurrence of Wolbachia in Aedes aegypti mosquitoes.

FEMS microbiology letters pii:5380775 [Epub ahead of print].

Wolbachia, a gram-ve bacterium, is widely known to be present in arthropods and nematodes. Of late, great impetus is given to employ this intracellular bacterium, as an alternative to conventional biocontrol agents for the control of mosquitoes because of its inherent ability to induce sperm-egg incompatibility, feminization etc. By employing molecular tools, we have shown the presence of Wolbachia from Aedes aegypti mosquito population collected from Coimbatore, India by PCR amplifying the Ae. aegypti mosquito genome with Wolbachia specific 16S rRNA, wsp and ftsZ gene primers. The phylogenetic analysis of these gene sequences incorporating MLST and GenBank reference sequences has confirmed the occurrence of Wolbachia supergroup B in Ae. aegypti. In addition, qRT-PCR results have shown the dynamics of Wolbachia across the developmental stages of mosquito. The absence of Wolbachia in tetracycline treated Ae. aegypti mosquitoes evidenced by transmission electron microscopy reinforced our finding conclusively. After confirming their persistence through generations, we have designated Wolbachia from Ae. aegypti as wAegB. In our considered view, wAegB could play a dynamic role in impeding mosquito multiplication and consequently impinging transmission of the dreadful dengue.

RevDate: 2019-03-14

Taylor MJ, von Geldern TW, Ford L, et al (2019)

Preclinical development of an oral anti-Wolbachia macrolide drug for the treatment of lymphatic filariasis and onchocerciasis.

Science translational medicine, 11(483):.

There is an urgent global need for a safe macrofilaricide drug to accelerate elimination of the neglected tropical diseases onchocerciasis and lymphatic filariasis. From an anti-infective compound library, the macrolide veterinary antibiotic, tylosin A, was identified as a hit against Wolbachia This bacterial endosymbiont is required for filarial worm viability and fertility and is a validated target for macrofilaricidal drugs. Medicinal chemistry was undertaken to develop tylosin A analogs with improved oral bioavailability. Two analogs, A-1535469 and A-1574083, were selected. Their efficacy was tested against the gold-standard second-generation tetracycline antibiotics, doxycycline and minocycline, in mouse and gerbil infection models of lymphatic filariasis (Brugia malayi and Litomosoides sigmodontis) and onchocerciasis (Onchocerca ochengi). A 1- or 2-week course of oral A-1535469 or A-1574083 provided >90% Wolbachia depletion from nematodes in infected animals, resulting in a block in embryogenesis and depletion of microfilarial worm loads. The two analogs delivered comparative or superior efficacy compared to a 3- to 4-week course of doxycycline or minocycline. A-1574083 (now called ABBV-4083) was selected for further preclinical testing. Cardiovascular studies in dogs and toxicology studies in rats and dogs revealed no adverse effects at doses (50 mg/kg) that achieved plasma concentrations >10-fold above the efficacious concentration. A-1574083 (ABBV-4083) shows potential as an anti-Wolbachia macrolide with an efficacy, pharmacology, and safety profile that is compatible with a short-term oral drug course for treating lymphatic filariasis and onchocerciasis.

RevDate: 2019-03-12

Wang J, Zhu X, Ying Z, et al (2019)

Prevalence of Dirofilaria immitis Infections In Dogs and Cats In Hainan Island/Province and Three Other Coastal Cities of China Based On Antigen Testing and PCR.

The Journal of parasitology, 105(2):199-202.

Canine and feline heartworm disease caused by Dirofilaria immitis is a serious and sometimes fatal infection transmitted by mosquitos. Little is known about the prevalence or distribution of D. immitis infection in dogs and cats on the island of Hainan island/province or coastal cities of China. The present study examined the occurrence of D. immitis infections in dogs (n = 869) and cats (n = 51) in Hainan island/province and prevalence in dogs from 3 coastal cities (Shenzhen [n = 55], Shanghai [n = 69], and Hangzhou [n = 45]) in southern and eastern China. A commercial antigen detection (AD) test and 2 PCR methods (16S ribosomal RNA and Wolbachia surface protein [ WSP] genes) were used to determine the prevalence of D. immitis from animals >6 mo old with no previous history of D. immitis preventive treatment or heartworm infection. Gene sequencing was used to confirm positive PCR samples. The AD test was not used on cat samples. Using the AD test, the prevalence in dogs was 0.5% (4/869) in Hainan island/province, 0% (0/55) in Shenzhen, 1.5% (1/69) in Shanghai, and 0% (0/45) in Hangzhou. Prevalence by 16S rRNA gene PCR was 7.4% (64/869) of dogs from Hainan island/province, 0% (0/55) in dogs from Shenzhen, 1.5% (1/69) in dogs from Shanghai, and 0% (0/45) in dogs from Hangzhou. Prevalence by WSP gene PCR in dogs was 5.3% (46/869) in Hainan island/province, 0% (0/55) in Shenzhen, 1.5% (1/69) in Shanghai, and 0% (0/45) in Hangzhou. Prevalence in the 51 cats from Hainan island/province was 9.8% and 5.9% by 16S rRNA and WSP gene PCR, respectively. The present study demonstrates that canine heartworm exposure occurs in dogs and cats in Hainan island/province and that PCR methods detected a higher prevalence than did the AD method. The 16S rRNA gene PCR detected more positive samples than did the WSP gene PCR in both dogs and cats. The 3 coastal cities had very few dogs that had evidence of D. immitis exposure.

RevDate: 2019-03-12

Brinker P, Fontaine MC, Beukeboom LW, et al (2019)

Host, Symbionts, and the Microbiome: The Missing Tripartite Interaction.

Trends in microbiology pii:S0966-842X(19)30040-X [Epub ahead of print].

Symbiosis between microbial associates and a host is a ubiquitous feature of life on earth, modulating host phenotypes. In addition to endosymbionts, organisms harbour a collection of host-associated microbes, the microbiome that can impact important host traits. In this opinion article we argue that the mutual influences of the microbiome and endosymbionts, as well as their combined influence on the host, are still understudied. Focusing on the endosymbiont Wolbachia, we present growing evidence indicating that host phenotypic effects are exerted in interaction with the remainder microbiome and the host. We thus advocate that only through an integrated approach that considers multiple interacting partners and environmental influences will we be able to gain a better understanding of host-microbe associations.

RevDate: 2019-03-08

Davydov II, Salamin N, M Robinson-Rechavi (2019)

Large-Scale Comparative Analysis of Codon Models Accounting for Protein and Nucleotide Selection.

Molecular biology and evolution pii:5371074 [Epub ahead of print].

There are numerous sources of variation in the rate of synonymous substitutions inside genes, such as direct selection on the nucleotide sequence, or mutation rate variation. Yet scans for positive selection rely on codon models which incorporate an assumption of effectively neutral synonymous substitution rate, constant between sites of each gene. Here we perform a large-scale comparison of approaches which incorporate codon substitution rate variation and propose our own simple yet effective modification of existing models. We find strong effects of substitution rate variation on positive selection inference. More than 70% of the genes detected by the classical branch-site model are presumably false positives caused by the incorrect assumption of uniform synonymous substitution rate. We propose a new model which is strongly favored by the data while remaining computationally tractable. With the new model we can capture signatures of nucleotide level selection acting on translation initiation and on splicing sites within the coding region. Finally, we show that rate variation is highest in the highly recombining regions, and we propose that recombination and mutation rate variation, such as high CpG mutation rate, are the two main sources of nucleotide rate variation. While we detect fewer genes under positive selection in Drosophila than without rate variation, the genes which we detect contain a stronger signal of adaptation of dynein, which could be associated with Wolbachia infection. We provide software to perform positive selection analysis using the new model.

RevDate: 2019-03-07

Idro R, Anguzu R, Ogwang R, et al (2019)

Doxycycline for the treatment of nodding syndrome (DONS); the study protocol of a phase II randomised controlled trial.

BMC neurology, 19(1):35 pii:10.1186/s12883-019-1256-z.

BACKGROUND: Nodding syndrome is a poorly understood neurological disorder of unknown aetiology, affecting several thousand children in Africa. There has been a consistent epidemiological association with infection by the filarial parasite, Onchocerca volvulus and antibodies to leiomodin and DJ-1, cross-reacting with O.volvulus proteins, have been reported. We hypothesized that nodding syndrome is a neuro-inflammatory disorder, induced by antibodies to O.volvulus or its symbiont, Wolbachia, cross-reacting with human neuron proteins and that doxycycline, which kills Onchocerca through effects on Wolbachia, may be used as treatment.

METHODS: This will be a two-arm, double-blind, placebo-controlled, randomised phase II trial of doxycycline 100 mg daily for six weeks in 230 participants. Participants will be patients' ages≥8 years with nodding syndrome. They will receive standard of care supportive treatment. All will be hospitalised for 1-2 weeks during which time baseline measurements including clinical assessments, EEG, cognitive and laboratory testing will be performed and antiepileptic drug doses rationalised. Participants will then be randomised to either oral doxycycline (Azudox®, Kampala Pharmaceutical Industries) 100 mg daily or placebo. Treatment will be initiated in hospital and continued at home. Participants will be visited at home at 2, 4 and 6 weeks for adherence monitoring. Study outcomes will be assessed at 6, 12, 18 and 24-month visits. Analysis will be by intention to treat. The primary efficacy outcome measure will be the proportion of patients testing positive and the levels or titires of antibodies to host neuron proteins (HNPs) and/or leiomodin at 24 months. Secondary outcome measures will include effect of the intervention on seizure control, inflammatory markers, cognitive function, disease severity and quality of life.

DISCUSSION: This trial postulates that targeting O.volvulus through drugs which kill Wolbachia can modify the pathogenic processes in nodding syndrome and improve outcomes. Findings from this study are expected to substantially improve the understanding and treatment of nodding syndrome.

TRIAL REGISTRATION: Registered with ID: NCT02850913 on 1st August, 2016.

RevDate: 2019-03-07

Kwon M, Seo SS, Kim MK, et al (2019)

Compositional and Functional Differences between Microbiota and Cervical Carcinogenesis as Identified by Shotgun Metagenomic Sequencing.

Cancers, 11(3): pii:cancers11030309.

Recent studies have reported the potential role of microbiomes in cervical disease. However, little is known about the microbiome composition and function in cervical carcinogenesis. We aimed to identify the compositional and functional alterations of cervical microbiomes in cases of cervical carcinogenesis of Korean women using shotgun metagenomic sequencing. In this study, using shotgun sequencing, we sequenced the cervical metagenomes of cervical intraneoplasia 2/3 (n = 17), cervical cancer (n = 12), and normal controls (n = 18) to identify the microbial abundances and enriched metabolic functions in cervical metagenomes. At the genus level, the microbiota of cervical cancer were differentially enriched with genera Alkaliphilus, Pseudothermotoga, and Wolbachia. Cervical intraepithelial neoplasia (CIN) 2/3 were enriched with Lactobacillus, Staphylococcus, and Candidatus Endolissoclinum. The normal group was enriched with Pseudoalteromonas and Psychrobacter. Further characterization of the functionalities of the metagenomes may suggest that six Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) that are involved in 10 pathways are associated with an increased risk of CIN2/3 and cervical cancer. Specifically, cervical metagenomes were enriched in the course of peptidoglycan synthesis and depleted by dioxin degradation and 4-oxalocrotonate tautomerase. The Cluster of Orthologous Groups (COG) category 'Defense mechanisms' was depleted in cervical cancer patients. Our findings based on shotgun metagenomic sequencing suggest that cervical microbiome community compositions and their metagenomics profiles differed between cervical lesions and normal subjects. Future studies should have larger sample sizes and/or aggregate their results to have sufficient power to detect reproducible and significant associations.

RevDate: 2019-03-06

Reveillaud J, Bordenstein SR, Cruaud C, et al (2019)

The Wolbachia mobilome in Culex pipiens includes a putative plasmid.

Nature communications, 10(1):1051 pii:10.1038/s41467-019-08973-w.

Wolbachia is a genus of obligate intracellular bacteria found in nematodes and arthropods worldwide, including insect vectors that transmit dengue, West Nile, and Zika viruses. Wolbachia's unique ability to alter host reproductive behavior through its temperate bacteriophage WO has enabled the development of new vector control strategies. However, our understanding of Wolbachia's mobilome beyond its bacteriophages is incomplete. Here, we reconstruct near-complete Wolbachia genomes from individual ovary metagenomes of four wild Culex pipiens mosquitoes captured in France. In addition to viral genes missing from the Wolbachia reference genome, we identify a putative plasmid (pWCP), consisting of a 9.23-kbp circular element with 14 genes. We validate its presence in additional Culex pipiens mosquitoes using PCR, long-read sequencing, and screening of existing metagenomes. The discovery of this previously unrecognized extrachromosomal element opens additional possibilities for genetic manipulation of Wolbachia.

RevDate: 2019-03-05

Pagel L, Bultman T, Górzyńska K, et al (2019)

Botanophila flies, vectors of Epichloë fungal spores, are infected by Wolbachia.

Mycology, 10(1):1-5 pii:1515119.

Epichloë fungi are endophytes within grasses that can form stromata on culms of their hosts. Botanophila flies visit the stromata for egg laying and in the process can vector spermatial spores, thereby cross fertilising the fungus. Following egg hatch, larval flies consume fungal tissue and spores. Thus, Epichloë individuals with traits that limit larval consumption could be at a selective advantage. We assessed Botanophila fly larvae from sites within the United States and Europe for infection by the bacterial sexual parasite Wolbachia through amplification of the Wolbachia surface protein gene (wsp). Nearly 70% of fly larvae in our samples were infected by Wolbachia. This is the first record of infection by Wolbachia within Botanophila and could have far reaching effects on not only the fly host, but also the Epichloë fungi upon which Botanophila feeds as well as the grass host within which the fungi live. For example, infection by Wolbachia could limit consumption of Epichloë spores by Botanophila larvae if the bacteria promoted premature larval death.

RevDate: 2019-03-01

Onder Z, Ciloglu A, Duzlu O, et al (2019)

Molecular detection and identification of Wolbachia endosymbiont in fleas (Insecta: Siphonaptera).

Folia microbiologica pii:10.1007/s12223-019-00692-5 [Epub ahead of print].

The aim of this study was to determine the presence and prevalence of Wolbachia bacteria in natural population of fleas (Insecta: Siphonaptera) in Turkey, and to exhibit the molecular characterization and the phylogenetic reconstruction at the positive isolates with other species in GenBank, based on 16S rDNA sequences. One hundred twenty-four flea samples belonging to the species Ctenocephalides canis, C. felis, and Pulex irritans were collected from animal shelters in Kayseri between January and August 2017. All flea species were individually screened for the presence of Wolbachia spp. by polymerase chain reaction (PCR) targeting the 16S ribosomal RNA gene. According to PCR analyses, Wolbachia spp. were found prevalent in C. canis and P. irritans fleas, while it was not detected in the C. felis species. Totally, 20 isolates were purified from agarose gel and sequenced with the same primers for molecular characterization and phylogenetic analyses. The sequence analyses revealed 17 polymorphic sites and 2 genetically different Wolbachia isolates, representing two different haplotypes in two flea species. The distribution patterns, molecular characterization, and phylogenetic status of Wolbachia spp. of fleas in Turkey are presented for the first time with this study. Understanding of the role of Wolbachia in vector biology may provide information for developing Wolbachia-based biological control tools.

RevDate: 2019-03-01

Fortin M, Meunier J, Laverré T, et al (2019)

Joint effects of group sex-ratio and Wolbachia infection on female reproductive success in the terrestrial isopod Armadillidium vulgare.

BMC evolutionary biology, 19(1):65 pii:10.1186/s12862-019-1391-6.

BACKGROUND: In species that reproduce with sexual reproduction, males and females often have opposite strategies to maximize their own fitness. For instance, males are typically expected to maximize their number of mating events, whereas an excessive number of mating events can be costly for females. Although the risk of sexual harassment by males and resulting costs for females are expected to increase with the proportion of males, it remains unknown whether and how parasitic distorters of a host population's sex-ratio can shape this effect on the fitness of females. Here, we addressed this question using Armadillidium vulgare and its parasite Wolbachia that alters the sex-ratio of a population. We set up Wolbachia-free and Wolbachia-infected females in experimental groups exhibiting 100, 80, 50% or 20% females for 1 year, during which we measured changes in survival, fertility and fecundity.

RESULTS: Wolbachia infection shaped the effects of both population sex-ratio and reproductive season on female fecundity. Compared to Wolbachia-free females, Wolbachia-infected females were less likely to be gravid in populations exhibiting an excess of females and did not exhibit the otherwise negative effect of seasons on this likelihood. Group sex-ratio and Wolbachia infection have independent effects on other measured traits. Male-biased populations had females both exhibiting the lowest survival rate after 6 months and producing the smallest number of offspring, independent of Wolbachia infection. Conversely, Wolbachia-infected females had the lowest likelihood of producing at least one offspring, independent of group sex-ratio. Wolbachia infection had no effect on female survival rate.

CONCLUSIONS: We demonstrated that male-biased sex-ratio and the presence of Wolbachia are costly for females due to sexual harassment by males and bacterial infection, respectively. Interestingly, Wolbachia infection triggers another negative effect. This effect does not come from an excess of males and its associated sexual harassment of females but instead from a lack of males and the associated risk for females of remaining unmated. Overall, these findings highlight the importance of social pressures and infection on female fitness and provide insights into our general understanding of the joint and opposite effects of these two parameters in the evolution of reproductive strategies.

RevDate: 2019-02-28

von Geldern TW, Morton HE, Clark RF, et al (2019)

Discovery of ABBV-4083, a novel analog of Tylosin A that has potent anti-Wolbachia and anti-filarial activity.

PLoS neglected tropical diseases, 13(2):e0007159 pii:PNTD-D-18-01874 [Epub ahead of print].

There is a significant need for improved treatments for onchocerciasis and lymphatic filariasis, diseases caused by filarial worm infection. In particular, an agent able to selectively kill adult worms (macrofilaricide) would be expected to substantially augment the benefits of mass drug administration (MDA) with current microfilaricides, and to provide a solution to treatment of onchocerciasis / loiasis co-infection, where MDA is restricted. We have identified a novel macrofilaricidal agent, Tylosin A (TylA), which acts by targeting the worm-symbiont Wolbachia bacterium. Chemical modification of TylA leads to improvements in anti-Wolbachia activity and oral pharmacokinetic properties; an optimized analog (ABBV-4083) has been selected for clinical evaluation.

RevDate: 2019-02-28

Staunton KM, Yeeles P, Townsend M, et al (2019)

Trap Location and Premises Condition Influences on Aedes aegypti (Diptera: Culicidae) Catches Using Biogents Sentinel Traps During a 'Rear and Release' Program: Implications for Designing Surveillance Programs.

Journal of medical entomology pii:5366979 [Epub ahead of print].

As the incidence of arboviral diseases such as dengue, Zika, chikungunya, and yellow fever increases globally, controlling their primary vector, Aedes aegypti (L.) (Diptera: Culicidae), is of greater importance than ever before. Mosquito control programs rely heavily on effective adult surveillance to ensure methodological efficacy. The Biogents Sentinel (BGS) trap is the gold standard for surveilling adult Aedes mosquitoes and is commonly deployed worldwide, including during modern 'rear and release' programs. Despite its extensive use, few studies have directly assessed environmental characteristics that affect BGS trap catches, let alone how these influences change during 'rear and release' programs. We assessed male and female Ae. aegypti spatial stability, as well as premises condition and trap location influences on BGS trap catches, as part of Debug Innisfail 'rear and release' program in northern Australia. We found similar trends in spatial stability of male and female mosquitoes at both weekly and monthly resolutions. From surveillance in locations where no males were released, reduced catches were found at premises that contained somewhat damaged houses and unscreened properties. In addition, when traps were located in areas that were unsheltered, more than 10 m from commonly used sitting areas or more visually complex catches were also negatively affected. In locations where males were released, we found that traps in treatment sites, relative to control sites, displayed increased catches in heavily shaded premises and were inconsistently influenced by differences in house sets and building materials. Such findings have valuable implications for a range of Ae. aegypti surveillance programs.

RevDate: 2019-02-28

Bykov RА, Yudina MA, Gruntenko NE, et al (2019)

Prevalence and genetic diversity of Wolbachia endosymbiont and mtDNA in Palearctic populations of Drosophila melanogaster.

BMC evolutionary biology, 19(Suppl 1):48 pii:10.1186/s12862-019-1372-9.

BACKGROUND: Maternally inherited Wolbachia symbionts infect D. melanogaster populations worldwide. Infection rates vary greatly. Genetic diversity of Wolbachia in D. melanogaster can be subdivided into several closely related genotypes coinherited with certain mtDNA lineages. mtDNA haplotypes have the following global distribution pattern: mtDNA clade I is mostly found in North America, II and IV in Africa, III in Europe and Africa, V in Eurasia, VI is global but very rare, and VIII is found in Asia. The wMel Wolbachia genotype is predominant in D. melanogaster populations. However, according to the hypothesis of global Wolbachia replacement, the wMelCS genotype was predominant before the XX century when it was replaced by the wMel genotype. Here we analyse over 1500 fly isolates from the Palearctic region to evaluate the prevalence, genetic diversity and distribution pattrern of the Wolbachia symbiont, occurrence of mtDNA variants, and finally to discuss the Wolbachia genotype global replacement hypothesis.

RESULTS: All studied Palearctic populations of D. melanogaster were infected with Wolbachia at a rate of 33-100%. We did not observe any significant correlation between infection rate and longitude or latitude. Five previously reported Wolbachia genotypes were found in Palearctic populations with a predominance of the wMel variant. The mtDNA haplotypes of the I_II_III clade and V clade were prevalent in Palearctic populations. To test the recent Wolbachia genotype replacement hypothesis, we examined three genomic regions of CS-like genotypes. Low genetic diversity was observed, only two haplotypes of the CS genotypes with a 'CCG' variant predominance were found.

CONCLUSION: The results of our survey of Wolbachia infection prevalence and genotype diversity in Palearctic D. melanogaster populations confirm previous studies. Wolbachia is ubiquitous in the Palearctic region. The wMel genotype is dominant with local occurrence of rare genotypes. Together with variants of the V mtDNA clade, the variants of the 'III+' clade are dominant in both infected and uninfected flies of Palearctic populations. Based on our data on Wolbachia and mtDNA in different years in some Palearctic localities, we can conclude that flies that survive the winter make the predominant symbiont contribution to the subsequent generation. A comprehensive overview of mtDNA and Wolbachia infection of D. melanogaster populations worldwide does not support the recent global Wolbachia genotype replacement hypothesis. However, we cannot exclude wMelCS genotype rate fluctuations in the past.

RevDate: 2019-02-27

Cândido EL, Silva UMD, LPG Cavalcanti (2019)

New record and extended geographical distribution of Aedes fluviatilis (Lutz, 1904) in Ceará, northeastern Brazil.

Revista da Sociedade Brasileira de Medicina Tropical, 52:e20180286 pii:S0037-86822019000100616.

INTRODUCTION: Aedes fluviatilis(Lutz, 1904) is considered a potential vector of yellow fever and dengue viruses and is naturally infected by Wolbachia.

METHODS: In March 2018, during a field activity in the municipality of Saboeiro, 163 mosquito larvae were collected in a dammed area of the Jaguaribe River.

RESULTS: Of the larvae collected, 143 (87.7%) were identified asAe. fluviatilis.

CONCLUSIONS: We report the first documentation of Ae. fluviatilis in the municipality of Saboeiro, northeastern Brazil. It is important to conduct additional entomological surveys to characterize the local Culicidae fauna. Ignoring the presence and dispersion of this vector could be a public health risk.

RevDate: 2019-02-26

Bagheri Z, Asghar Talebi A, Asgari S, et al (2019)

Wolbachia induce cytoplasmic incompatibility and affect mate preference in Habrobracon hebetor to increase the chance of its transmission to the next generation.

Journal of invertebrate pathology pii:S0022-2011(18)30386-0 [Epub ahead of print].

Wolbachia are common intracellular bacteria that are generally found in arthropods, including a high proportion of insects and also some nematodes. This intracellular symbiont can affect sex ratio with a variety of reproductive anomalies in the host, including cytoplasmic incompatibility (CI) in haplodiploids. In this study, we questioned if the parasitoid wasp, Habrobracon hebetor (Hym.: Braconidae), an important biological control agent of many lepidopteran larvae, is infected with Wolbachia. To test this, DNA was extracted from adult insects and subjected to PCR using specific primers to Wolbachia target genes. The results showed a high rate of Wolbachia infection in this parasitoid wasp. To determine the biological function of Wolbachia in H. hebetor, we removed this bacterium from the wasps using antibiotic treatment (cured wasps). Results of crossing experiments revealed that Wolbachia induced CI in H. hebetor in which cured females crossed with infected males produced only males, while both male and female progeny were observed for other crosses. Also, we showed that the presence of Wolbachia in females increased fecundity and female offspring of this parasitoid wasp. The presence of Wolbachia in the males had no significant effect on fecundity and female production, but might have incurred costs. We also investigated the effect of Wolbachia on mate choice and found that Wolbachia affects mating behavior of H. hebetor. Together, we showed that Wolbachia induces CI in H. hebetor and affects host mating behavior in favor of its transmission. Wolbachia utilize these strategies to increase the frequency of infected females in the host population.

RevDate: 2019-02-24

Singhal K, S Mohanty (2019)

Genome organisation and comparative genomics of four novel Wolbachia genome assemblies from Indian Drosophila host.

Functional & integrative genomics pii:10.1007/s10142-019-00664-5 [Epub ahead of print].

Wolbachia has long been known to share an endosymbiotic relationship with its host as an obligate intracellular organism. Wolbachia diversity as different supergroups is found to be host-specific in most cases except a few, where the host species is seen to accommodate multiple strains. Besides, the Wolbachia genome must have undergone several changes in response to the evolving host genome in order to adapt and establish a strong association with its host, thus making a distinctive Wolbachia-host alliance. The present study focusses on four novel genome assembly and genome-wide sequence variations of Indian Wolbachia strains, i.e. wMel and wRi isolated from two different Drosophila hosts. The genome assembly has an average size of ~ 1.1 Mb and contains ~ 1100 genes, which is comparable with the previously sequenced Wolbachia genomes. The comparative genomics analysis of these genomes and sequence-wide comparison of some functionally significant genes, i.e. ankyrin repeats, Wsp and T4SS, highlight their sequence similarities and dissimilarities, further supporting the strain-specific association of Wolbachia to its host. Interestingly, some of the sequence variations are also found to be restricted to only Indian Wolbachia strains. Further analysis of prophage and their flanking regions in the Wolbachia genome reveals the presence of several functional genes which may assist the phage to reside inside the bacterial host, thus providing a trade-off for the endosymbiont-host association. Understanding this endosymbiont genome in different eco-geographical conditions has become imperative for the recent use of Wolbachia in medical entomology as a vector-control agent.

RevDate: 2019-02-23

Newton ILG, BE Slatko (2019)

Symbiosis Comes of age at the 10th Biennial Meeting of Wolbachia Researchers.

Applied and environmental microbiology pii:AEM.03071-18 [Epub ahead of print].

Wolbachia pipientis is an alpha-proteobacterial, obligate intracellular microbe and arguably the most successful infection on our planet, colonizing 40-60% of insect species. Wolbachia are also present in most, but not all, filarial nematodes where they are obligate mutualists and are the targets for anti-filarial drug discovery. Although Wolbachia are related to important human pathogens they do not infect mammals, but instead are well known for their reproductive manipulations of insect populations, inducing the following phenotypes: male-killing, feminization, parthenogenesis induction, or cytoplasmic incompatibility (CI). The most common of these, CI, results in a sperm-egg incompatibility and increases the relative fecundity of infected females in a population. In the last decade, Wolbachia have also been shown to provide a benefit to insects, where the infection can inhibit RNA virus replication within the host. Wolbachia cannot be cultivated outside of host cells and no genetic tools are available in the symbiont, limiting approaches available to its study. This means that many questions fundamental to our understanding of Wolbachia basic biology remained unknown for decades. The tenth biennial international Wolbachia conference, "Wolbachia Evolution, Ecology, Genomics and Cell Biology: A Chronicle of the Most Ubiquitous Symbiont", was held on June 17-22, 2018, Salem, MA USA. In the review below we highlight the new science presented at the meeting, link it to prior efforts to answer these questions across the Wolbachia genus, and the importance to the field of symbiosis. The topics covered in this review are based on the presentations at the conference.

RevDate: 2019-02-14

Martínez-Rodríguez P, Rolán-Alvarez E, Del Mar Pérez-Ruiz M, et al (2019)

Geographic and Temporal Variation of Distinct Intracellular Endosymbiont Strains of Wolbachia sp. in the Grasshopper Chorthippus parallelus: a Frequency-Dependent Mechanism?.

Microbial ecology pii:10.1007/s00248-019-01338-2 [Epub ahead of print].

Wolbachia is an intracellular endosymbiont that can produce a range of effects on host fitness, but the temporal dynamics of Wolbachia strains have rarely been experimentally evaluated. We compare interannual strain frequencies along a geographical region for understanding the forces that shape Wolbachia strain frequency in natural populations of its host, Chorthippus parallelus (Orthoptera, Acrididae). General linear models show that strain frequency changes significantly across geographical and temporal scales. Computer simulation allows to reject the compatibility of the observed patterns with either genetic drift or sampling errors. We use consecutive years to estimate total Wolbachia strain fitness. Our estimation of Wolbachia fitness is significant in most cases, within locality and between consecutive years, following a negatively frequency-dependent trend. Wolbachia spp. B and F strains show a temporal pattern of variation that is compatible with a negative frequency-dependent natural selection mechanism. Our results suggest that such a mechanism should be at least considered in future experimental and theoretical research strategies that attempt to understand Wolbachia biodiversity.

RevDate: 2019-02-14

Showler AJ, Kubofcik J, Ricciardi A, et al (2019)

Differences in the Clinical and Laboratory Features of Imported Onchocerciasis in Endemic Individuals and Temporary Residents.

The American journal of tropical medicine and hygiene [Epub ahead of print].

Many parasitic infections have different presenting features in endemic individuals (ENDs) and immunologically naive temporary residents (TRs). Temporary residents with loiasis often display acute symptoms and hypereosinophilia, in contrast to a parasite-induced subclinical state in chronically infected ENDs. Few studies have examined differences in ENDs and TRs infected with the related filarial parasite Onchocerca volvulus. We identified 40 TRs and 36 ENDs with imported onchocerciasis at the National Institutes of Health between 1976 and 2016. All study subjects received an extensive pretreatment history review, physical examination, and laboratory investigations. We performed additional parasite-specific serologic testing on stored patient sera. Asymptomatic infection occurred in 12.5% of TRs and no ENDs (P = 0.06). Papular dermatitis was more common in TRs (47.5% versus 2.7%, P < 0.001), whereas more pigmentation changes occurred in ENDs (41.7% versus 15%, P = 0.01). Only endemic patients reported visual disturbance (13% versus 0%, P = 0.03). One TR (3.3%) had onchocercal eye disease, compared with 22.6% of ENDs (P = 0.053). Absolute eosinophil counts (AECs) were similar in ENDs and TRs (P = 0.5), and one-third of subjects had a normal AEC. Endemic individuals had higher filarial-specific IgG4 and were more likely to be positive for IgG4 antibodies to Ov-16. Temporary residents and ENDs with imported O. volvulus infection presented with different dermatologic manifestations; ocular involvement occurred almost exclusively in ENDs. Unlike Loa loa, clinical differences appear not to be eosinophil mediated and may reflect chronicity, intensity of infection, or the presence of Wolbachia in O. volvulus.

RevDate: 2019-02-12

Chegeni TN, M Fakhar (2019)

Promising role of Wolbachia as anti-parasitic drug target and eco-friendly biocontrol agent.

Recent patents on anti-infective drug discovery pii:PRI-EPUB-96563 [Epub ahead of print].

BACKGROUND: Wolbachia is the most common endosymbiotic bacteria in insect-borne parasites and it is the most common reproductive parasite in the world. Wolbachia has been found worldwide in numerous arthropod and parasite species, including: insects, terrestrial isopods, spiders, mites and filarial nematodes. There is a complicated relationship between Wolbachia and its hosts and in some cases, they create a mutual relationship instead of a parasitic relationship. Some species are not able to reproduce in the absence of infection with Wolbachia. Thus, use of existing strains of Wolbachia bacteria offers a potential strategy for control the population of mosquitoes and other pests and diseases.

METHODS: We searched ten databases and reviewed published papers regarding the role of Wolbachia as promising drug target and emerging biological control agent of parasitic diseases between 1996 and 2017 (22 years) were considered eligible. Also, in the current study several patents (WO008652), (US7723062), (US 0345249 A1) were reviewed.

RESULTS: Endosymbiotic Wolbachia bacteria, which is inherited from mothers, is transmitted to mosquitoes and interfere with pathogen transmission. They can change the reproduction of their host. Wolbachia is transmitted through the cytoplasm of eggs and have evolved different mechanisms for manipulating reproduction of its hosts, including induction of reproductive incompatibility, parthenogenesis, and feminization. Wolbachia extensive effects on reproduction and host fitness have made Wolbachia the issue of growing attention as a potential biocontrol agent.

CONCLUSION: Wolbachia has opened a new window to design costly, potent and eco-friendly for effective treatment and elimination of vector-borne parasitic diseases.

RevDate: 2019-02-12

Augustinos AA, Moraiti CA, Drosopoulou E, et al (2019)

Old residents and new arrivals of Rhagoletis species in Europe.

Bulletin of entomological research pii:S0007485319000063 [Epub ahead of print].

The genus Rhagoletis (Diptera: Tephritidae) comprises more than 65 species distributed throughout Europe, Asia and America, including many species of high economic importance. Currently, there are three Rhagoletis species that infest fruits and nuts in Europe. The European cherry fruit fly, Rhagoletis cerasi (may have invaded Europe a long time ago from the Caucasian area of West Asia), and two invasive species (recently introduced from North America): the eastern American cherry fruit fly, R. cingulata, and the walnut husk fly, R. completa. The presence of different Rhagoletis species may enhance population dynamics and establish an unpredictable economic risk for several fruit and nut crops in Europe. Despite their excessive economic importance, little is known on population dynamics, genetics and symbiotic associations for making sound pest control decisions in terms of species-specific, environmental friendly pest control methods. To this end, the current paper (a) summarizes recently accumulated genetic and population data for the European Rhagoletis species and their association with the endosymbiont Wolbachia pipientis, and (b) explores the possibility of using the current knowledge for implementing the innovative biological control methods of sterile insect technique and incompatible insect technique.

RevDate: 2019-02-08

Ju H, Zhu D, M Qiao (2019)

Effects of polyethylene microplastics on the gut microbial community, reproduction and avoidance behaviors of the soil springtail, Folsomia candida.

Environmental pollution (Barking, Essex : 1987), 247:890-897 pii:S0269-7491(18)35319-3 [Epub ahead of print].

Microplastics (MPs) are an emerging contaminant and are confirmed to be ubiquitous in the environment. Adverse effects of MPs on aquatic organisms have been widely studied, whereas little research has focused on soil invertebrates. We exposed the soil springtail Folsomia candida to artificial soils contaminated with polyethylene MPs (<500 μm) for 28 d to explore the effects of MPs on avoidance, reproduction, and gut microbiota. Springtails exhibited avoidance behaviors at 0.5% and 1% MPs (w/w in dry soil), and the avoidance rate was 59% and 69%, respectively. Reproduction was inhibited when the concentration of MPs reached 0.1% and was reduced by 70.2% at the highest concentration of 1% MPs compared to control. The half-maximal effective concentration (EC50) value based on reproduction for F. candida was 0.29% MPs. At concentrations of 0.5% dry weight in the soil, MPs significantly altered the microbial community and decreased bacterial diversity in the springtail gut. Specifically, the relative abundance of Wolbachia significantly decreased while the relative abundance of Bradyrhizobiaceae, Ensifer and Stenotrophomonas significantly increased. Our results demonstrated that MPs exerted a significant toxic effect on springtails and can change their gut microbial community. This can provide useful information for risk assessment of MPs in terrestrial ecosystems.

RevDate: 2019-02-07

Jacobs RT, Lunde CS, Freund YR, et al (2019)

Boron-Pleuromutilins as Anti-Wolbachia Agents with Potential for Treatment of Onchocerciasis and Lymphatic Filariasis.

Journal of medicinal chemistry [Epub ahead of print].

A series of pleuromutilins modified by introduction of a boron-containing heterocycle on C(14) of the polycyclic core are described. These analogs were found to be potent anti-Wolbachia antibiotics, and as such, may be useful in the treatment of filarial infections caused by Onchocherca volvulus, resulting in Onchocerciasis or river blindness, or Wuchereria bancrofti and Brugia malayi and related parasitic nematodes resulting in lymphatic filariasis. These two important Neglected Tropical diseases (NTDs) disproportionately impact patients in the developing world. The lead preclinical candidate compound containing a 7-fluoro-6-oxybenzoxaborole (15, AN11251) was shown to have good in vitro anti-Wolbachia activity and physicochemical and pharmacokinetic properties providing high exposure in plasma. The lead was effective in reducing the Wolbachia load in filarial worms following oral administration to mice.

RevDate: 2019-02-07

Simo G, Kanté ST, Madinga J, et al (2019)

Molecular identification of Wolbachia and Sodalis glossinidius in the midgut of Glossina fuscipes quanzensis from the Democratic Republic of Congo.

Parasite (Paris, France), 26:5.

During the last 30 years, investigations on the microbiome of different tsetse species have generated substantial data on the bacterial flora of these cyclical vectors of African trypanosomes, with the overarching goal of improving the control of trypanosomiases. It is in this context that the presence of Wolbachia and Sodalis glossinidius was studied in wild populations of Glossina fuscipes quanzensis from the Democratic Republic of Congo. Tsetse flies were captured with pyramidal traps. Of the 700 Glossina f. quanzensis captured, 360 were dissected and their midguts collected and analyzed. Sodalis glossinidius and Wolbachia were identified by PCR. The Wolbachia-positive samples were genetically characterized with five molecular markers. PCR revealed 84.78% and 15.55% midguts infected by Wolbachia and S. glossinidius, respectively. The infection rates varied according to capture sites. Of the five molecular markers used to characterize Wolbachia, only the fructose bis-phosphate aldolase gene was amplified for about 60% of midguts previously found with Wolbachia infections. The sequencing results confirmed the presence of Wolbachia and revealed the presence of S. glossinidius in the midgut of Glossina f. quanzensis. A low level of midguts were naturally co-infected by both bacteria. The data generated in this study open a framework for investigations aimed at understanding the contribution of these symbiotic microorganisms to the vectorial competence of Glossina fuscipes quanzensis.

RevDate: 2019-02-07

Horváth G, Garamszegi LZ, Bereczki J, et al (2019)

Roll with the fear: environment and state dependence of pill bug (Armadillidium vulgare) personalities.

Die Naturwissenschaften, 106(3-4):7 pii:10.1007/s00114-019-1602-4.

Most studies on animal personality evaluate individual mean behaviour to describe individual behavioural strategy, while often neglecting behavioural variability on the within-individual level. However, within-individual behavioural plasticity (variation induced by environment) and within-individual residual variation (regulatory behavioural precision) are recognized as biologically valid components of individual behaviour, but the evolutionary ecology of these components is still less understood. Here, we tested whether behaviour of common pill bugs (Armadillidium vulgare) differs on the among- and within-individual level and whether it is affected by various individual specific state-related traits (sex, size and Wolbachia infection). To this aim, we assayed risk-taking in familiar vs. unfamiliar environments 30 times along 38 days and applied double modelling statistical technique to handle the complex hierarchical structure for both individual-specific trait means and variances. We found that there are significant among-individual differences not only in mean risk-taking behaviour but also in environment- and time-induced behavioural plasticity and residual variation. Wolbachia-infected individuals took less risk than healthy conspecifics; in addition, individuals became more risk-averse with time. Residual variation decreased with time, and individuals expressed higher residual variation in the unfamiliar environment. Further, sensitization was stronger in females and in larger individuals in general. Our results suggest that among-individual variation, behavioural plasticity and residual variation are all (i) biologically relevant components of an individual's behavioural strategy and (ii) responsive to changes in environment or labile state variables. We propose pill bugs as promising models for personality research due to the relative ease of getting repeated behavioural measurements.

RevDate: 2019-02-07

Kampfraath AA, Klasson L, Anvar SY, et al (2019)

Genome expansion of an obligate parthenogenesis-associated Wolbachia poses an exception to the symbiont reduction model.

BMC genomics, 20(1):106 pii:10.1186/s12864-019-5492-9.

BACKGROUND: Theory predicts that dependency within host-endosymbiont interactions results in endosymbiont genome size reduction. Unexpectedly, the largest Wolbachia genome was found in the obligate, parthenogenesis-associated wFol. In this study, we investigate possible processes underlying this genome expansion by comparing a re-annotated wFol genome to other Wolbachia genomes. In addition, we also search for candidate genes related to parthenogenesis induction (PI).

RESULTS: Within wFol, we found five phage WO regions representing 25.4% of the complete genome, few pseudogenized genes, and an expansion of DNA-repair genes in comparison to other Wolbachia. These signs of genome conservation were mirrored in the wFol host, the springtail F. candida, which also had an expanded DNA-repair gene family and many horizontally transferred genes. Across all Wolbachia genomes, there was a strong correlation between gene numbers of Wolbachia strains and their hosts. In order to identify genes with a potential link to PI, we assembled the genome of an additional PI strain, wLcla. Comparisons between four PI Wolbachia, including wFol and wLcla, and fourteen non-PI Wolbachia yielded a small set of potential candidate genes for further investigation.

CONCLUSIONS: The strong similarities in genome content of wFol and its host, as well as the correlation between host and Wolbachia gene numbers suggest that there may be some form of convergent evolution between endosymbiont and host genomes. If such convergent evolution would be strong enough to overcome the evolutionary forces causing genome reduction, it would enable expanded genomes within long-term obligate endosymbionts.

RevDate: 2019-02-06

Buchman A, Gamez S, Li M, et al (2019)

Engineered resistance to Zika virus in transgenic Aedes aegypti expressing a polycistronic cluster of synthetic small RNAs.

Proceedings of the National Academy of Sciences of the United States of America pii:1810771116 [Epub ahead of print].

Recent Zika virus (ZIKV) outbreaks have highlighted the necessity for development of novel vector control strategies to combat arboviral transmission, including genetic versions of the sterile insect technique, artificial infection with Wolbachia to reduce population size and/or vectoring competency, and gene drive-based methods. Here, we describe the development of mosquitoes synthetically engineered to impede vector competence to ZIKV. We demonstrate that a polycistronic cluster of engineered synthetic small RNAs targeting ZIKV is expressed and fully processed in Aedes aegypti, ensuring the formation of mature synthetic small RNAs in the midgut where ZIKV resides in the early stages of infection. Critically, we demonstrate that engineered Ae. aegypti mosquitoes harboring the anti-ZIKV transgene have significantly reduced viral infection, dissemination, and transmission rates of ZIKV. Taken together, these compelling results provide a promising path forward for development of effective genetic-based ZIKV control strategies, which could potentially be extended to curtail other arboviruses.

RevDate: 2019-02-05

Bogacheva AS, Shaikevich EV, Rakova VM, et al (2017)


Meditsinskaia parazitologiia i parazitarnye bolezni, 1(1):43-47.

The fauna of bloodsucking mosquitoes in the Nizhny Novgorod Region is represented by 11 species from 5 genera of the family Culicidae. During 2014-2015, the predominant species were Ochlerotatus cantans and Aedes cinereus mosqui- toes in both a population aggregate and woodland. The infected mosquitoes accounted for 1.3% of their total number and were registered only in the village of Fokino. The investigators identified two human pathogenic nematode species: Diro- filaria immits and Dirofilaria repens (0.9% and 0.4% respectively). The effective carriers of Dirofilaria in the examined area can be Ae.cinereus and Och.cantans as only these species were found to have an invasive stage of the parasite. The symbiotic bacterium Wolbachia was detected in the mosquitoes that were not infected with dirofilariasis. This is the first study in Russia to investigate the effects of Wolbachia on the susceptibility of dirofilariasis vectors to infection.

RevDate: 2019-02-04

Odeniran PO, Macleod ET, Ademola IO, et al (2019)

Endosymbionts interaction with trypanosomes in Palpalis group of Glossina captured in southwest Nigeria.

Parasitology international pii:S1383-5769(18)30467-7 [Epub ahead of print].

Glossina species epidemiological studies were conducted in "fly-belt" endemic zone of southwest Nigeria. Two major study areas were identified and four Nzi traps were set in each site for tsetse collection. This study was conducted to determine the prevalence of endosymbionts (Wigglesworthia glossinidia, Sodalis glossinidius and Wolbachia) in natural field-trapped populations of G. p. palpalis and G. tachinoides and investigate the corresponding interactions with African trypanosomes. A total of 64 tsetse flies were collected, these included G. p. palpalis (n = 28) and G. tachinoides (n = 36). Trypanosome infection and endosymbionts of these flies were determined using polymerase chain reaction (PCR) amplification. The infection rates of W. glossinidia was 100.0% in both species, no flies were positive for Wolbachia. Sodalis glossinidius prevalence was similar between the two-tsetse species, with G. p. palpalis and G. tachinoides showing prevalence of 35.7% (95%CI: 20.7-54.2) and 27.8% (95%CI: 15.9-44.0) respectively. No relationship was found between the endosymbionts and trypanosomes in trapped tsetse flies. More studies are needed to enhance the potential control interventions mediated by endosymbionts to reduce parasitic infections.

RevDate: 2019-02-04

Sinha A, Li Z, Sun L, et al (2019)

Complete Genome Sequence of the Wolbachia wAlbB Endosymbiont of Aedes albopictus.

Genome biology and evolution pii:5305888 [Epub ahead of print].

Wolbachia, an alpha-proteobacterium closely related to Rickettsia, is a maternally transmitted, intracellular symbiont of arthropods and nematodes. Aedes albopictus mosquitoes are naturally infected with Wolbachia strains wAlbA and wAlbB. Cell line Aa23 established from Ae. albopictus embryos retains only wAlbB and is a key model to study host-endosymbiont interactions. We have assembled the complete circular genome of wAlbB from the Aa23 cell line using long-read PacBio sequencing at 500X median coverage. The assembled circular chromosome is 1.48 megabases in size, an increase of more than 300 kb over the published draft wAlbB genome. The annotation of the genome identified 1,205 protein coding genes, 34 tRNA, 3 rRNA, 1 tmRNA and 3 other ncRNA loci. The long reads enabled sequencing over complex repeat regions which are difficult to resolve with short-read sequencing. Thirteen percent of the genome is comprised of IS elements distributed throughout the genome, some of which cause pseudogenization. Prophage WO genes encoding some essential components of phage particle assembly are missing, while the remainder are found in 5 prophage regions/WO-like islands or scattered around the genome. Orthology analysis identified a core proteome of 535 orthogroups across all completed Wolbachia genomes. The majority of proteins could be annotated using Pfam and eggNOG analyses, including ankyrins and components of the T4SS. KEGG analysis revealed the absence of 5 genes in wAlbB which are present in other Wolbachia. The availability of a complete circular chromosome from wAlbB will enable further biochemical, molecular and genetic analyses on this strain and related Wolbachia.

RevDate: 2019-02-04

Fromont C, Adair KL, AE Douglas (2019)

Correlation and causation between the microbiome, Wolbachia and host functional traits in natural populations of drosophilid flies.

Molecular ecology [Epub ahead of print].

Resident microorganisms are known to influence the fitness and traits of animals under controlled laboratory conditions, but, the relevance of these findings to wild animals is uncertain. This study investigated the host functional correlates of microbiota composition in a wild community of three sympatric species of mycophagous drosophilid flies, Drosophila falleni, D. neotestacea and D. putrida. Specifically, we quantified bacterial communities and host transcriptomes by parallel 16S rRNA gene amplicon sequencing and RNA-Seq of individual flies. Among-fly variation in microbiota composition did not partition strongly by sex or species, and included multiple modules, i.e. sets of bacterial taxa whose abundance varied in concert across different flies. The abundance of bacteria in several modules varied significantly with multiple host transcripts, especially in females, but the identity of the correlated host transcriptional functions differed with host species, including epithelial barrier function in D. falleni, muscle function in D. putrida, and insect growth and development in D. neotestacea. In D. neotestacea, which harbors the endosymbionts Wolbachia and Spiroplasma, Wolbachia promotes the abundance of Spiroplasma, and is positively correlated with abundance of Lactobacillales and Bacteroidales. Furthermore, most correlations between host gene expression and relative abundance of bacterial modules were co-correlated with abundance of Wolbachia (but not Spiroplasma), indicative of an inter-dependence between host functional traits, microbiota composition and Wolbachia abundance in this species. These data suggest that, in these natural populations of drosophilid flies, different host species interact with microbial communities in functionally different ways that can vary with the abundance of endosymbionts. This article is protected by copyright. All rights reserved.

RevDate: 2019-02-01

Shaikevich E, Bogacheva A, Rakova V, et al (2019)

Wolbachia symbionts in mosquitoes: Intra- and intersupergroup recombinations, horizontal transmission and evolution.

Molecular phylogenetics and evolution pii:S1055-7903(18)30184-2 [Epub ahead of print].

Many mosquitoes harbour Wolbachia symbionts that could affect the biology of their host in different ways. Evolutionary relationships of mosquitoes' Wolbachia infection, geographical distribution and symbiont prevalence in many mosquito species are not yet clear. Here, we present the results of Wolbachia screening of 17 mosquito species of four genera-Aedes, Anopheles, Coquillettidia and Culex collected from five regions of Eastern Europe and the Caucasus in 2012-2016. Based on multilocus sequence typing (MLST) data previously published and generated in this study, we try to reveal genetic links between mosquitoes' and other hosts' Wolbachia. The Wolbachia symbionts are found in Culex pipiens, Aedes albopictus and Coquillettidia richiardii and for the first time in Aedes cinereus and Aedes cantans, which are important vectors of human pathogens. Phylogenetic analysis demonstrated multiple origins of infection in mosquitoes although the one-allele-criterion approach revealed links among B-supergroup mosquito Wolbachia with allele content of lepidopteran hosts. The MLST gene content of strain wAlbA from the A-supergroup is linked with different ant species. Several cases of intersupergroup recombinations were found. One of them occurred in the wAlbaB strain of Aedes albopictus, which contains the coxA allele of the A-supergroup, whereas other loci, including wsp, belong to supergroup B. Other cases are revealed for non-mosquito symbionts and they exemplified genetic exchanges of A, B and F supergroups. We conclude that modern Wolbachia diversity in mosquitoes and in many other insect taxa is a recent product of strain recombination and symbiont transfers.

RevDate: 2019-02-01

Konecka E, Z Olszanowski (2019)

Phylogenetic analysis based on the 16S rDNA, gltA, gatB, and hcpA gene sequences of Wolbachia sp. from the novel host Ceratozetes thienemanni (Acari: Oribatida).

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(18)30765-2 [Epub ahead of print].

We determined the occurrence of intracellular endosymbionts (Wolbachia sp., Cardinium sp., Arsenophonus sp., Rickettsia sp., Spiroplasma sp., Hamiltonella sp., Flavobacterium, and microsporidia) in oribatid mites (Acari: Oribatida) with the use of PCR technique. For the first time we looked for and detected Wolbachia sp. in parthenogenetic oribatid mite Ceratozetes thienemanni Willmann, 1943. The 16S rDNA, gatB, hcpA, and gltA sequences of Wolbachia sp. in C. thienemanni showed the highest similarity (≥ 90%) to the genes of Wolbachia sp. from springtails Collembola and oribatid mite Gustavia microcephala. We found the unique sequence 5'-GGGGTAATGGCC-3' in 16S rDNA of Wolbachia sp. from C. thienemanni and collembolan representing group E. The phylogeny of Wolbachia sp. based on the analysis of single genes as well as concatenated alignments of four bacterial loci showed that the bacteria from C. thienemanni belonged to Wolbachia sp. group E, like the endosymbionts from springtail hosts and G. microcephala. Considering coexisting of representatives of Oribatida and Collembola in the same soil habitat and similar food, it is possible that the source of Wolbachia sp. infection was the same. Residues of dead invertebrates could be in organic matter of their soil food, so the scenario of infection transferred by eating of remains of soil cohabitates is also possible. It could explain the similarity and relationship of the Wolbachia sp. in these two arthropod groups. Oribatid mite C. thienemanni is a parthenogenetic mite which is a unique feature in the genus Ceratozetes. Moreover, this species, within the entire genus Ceratozetes, is characterized by the most northerly distribution. It is difficult to determine either it is parthenogenesis or the presence of endosymbionts that are in some way responsible for this kind of evolutionary success. Maybe we are dealing here with a kind of synergy of both factors?

RevDate: 2019-01-31

Fukui Y, H Inokuma (2019)

Subclinical infections of Anaplasma phagocytophilum and Anaplasma bovis in dogs in Ibaraki, Japan.

Japanese journal of infectious diseases [Epub ahead of print].

The prevalence of Anaplasma infection in 332 dogs from Ibaraki, Japan, was evaluated by serological and molecular surveys. Immunofluorescence antibody assay (IFA) against Anaplasma phagocytophilum indicated that 7 (2.1%) of 328 dogs were positive for A. phagocytophilum. Screening PCR demonstrated that 8 (2.4%) of 331 dogs were positive for Anaplasmataceae. Phylogenetic analysis of the partial 16S rRNA sequence of PCR amplicons revealed that 6 sequences were most similar to the 16S rRNA sequence of Wolbachia sp. and the remaining 2 to Anaplasma bovis. Further analysis by A. phagocytophilum-specific nested PCR demonstrated that 1 dog infected with A. bovis was also positive for A. phagocytophilum. This is the first study to report the dual infection of a dog in Japan with A. bovis and A. phagocytophilum.

RevDate: 2019-01-30

Russell SL, Lemseffer N, WT Sullivan (2019)

Correction: Wolbachia and host germline components compete for kinesin-mediated transport to the posterior pole of the Drosophila oocyte.

PLoS pathogens, 15(1):e1007557 pii:PPATHOGENS-D-19-00024.

[This corrects the article DOI: 10.1371/journal.ppat.1007216.].

RevDate: 2019-01-30

Kajtoch Ł, Kolasa M, Kubisz D, et al (2019)

Using host species traits to understand the Wolbachia infection distribution across terrestrial beetles.

Scientific reports, 9(1):847 pii:10.1038/s41598-018-38155-5.

Knowledge of Wolbachia prevalence with respect to its hosts is restricted mainly to taxonomic/phylogenetic context. In contrast, relations between infection and most host's ecological and biological traits are poorly understood. This study aimed to elaborate on relations between bacteria and its beetle hosts in taxonomic and the ecological contexts. In particular, the goal is to verify which ecological and biological traits of beetles could cause them to be prone to be infected. Verification of Wolbachia infection status across 297 beetle taxa showed that approximately 27% of taxa are infected by supergroups A and B. Only minor support for coevolution between bacteria and its beetle hosts was observed in some genera of beetles, but in general coevolution between beetles and Wolbachia was rejected. Some traits of beetles were found to be unrelated to Wolbachia prevalence (type of range and thermal preferences); some traits were related with ambiguous effects (habitats, distribution, mobility and body size); some were substantially related (reproduction mode and trophy). The aforementioned summary does not show obvious patterns of Wolbachia prevalence and diversity in relation to host taxonomy, biology, and ecology. As both Wolbachia and Coleoptera are diverse groups, this lack of clear patterns is probably a reflection of nature, which is characterised by highly diversified and probably unstable relations.

RevDate: 2019-01-27

Beckmann JF, Bonneau M, Chen H, et al (2019)

The Toxin-Antidote Model of Cytoplasmic Incompatibility: Genetics and Evolutionary Implications.

Trends in genetics : TIG pii:S0168-9525(18)30223-3 [Epub ahead of print].

Wolbachia bacteria inhabit the cells of about half of all arthropod species, an unparalleled success stemming in large part from selfish invasive strategies. Cytoplasmic incompatibility (CI), whereby the symbiont makes itself essential to embryo viability, is the most common of these and constitutes a promising weapon against vector-borne diseases. After decades of theoretical and experimental struggle, major recent advances have been made toward a molecular understanding of this phenomenon. As pieces of the puzzle come together, from yeast and Drosophila fly transgenesis to CI diversity patterns in natural mosquito populations, it becomes clearer than ever that the CI induction and rescue stem from a toxin-antidote (TA) system. Further, the tight association of the CI genes with prophages provides clues to the possible evolutionary origin of this phenomenon and the levels of selection at play.

RevDate: 2019-01-25

Duffy E, Archer CR, Sharma MD, et al (2019)

Wolbachia infection can bias estimates of intralocus sexual conflict.

Ecology and evolution, 9(1):328-338 pii:ECE34744.

Males and females share most of their genome and develop many of the same traits. However, each sex frequently has different optimal values for these shared traits, creating intralocus sexual conflict. This conflict has been observed in wild and laboratory populations of insects and affects important evolutionary processes such as sexual selection, the maintenance of genetic variation, and possibly even speciation. Given the broad impacts of intralocus conflict, accurately detecting and measuring it is important. A common way to detect intralocus sexual conflict is to calculate the intersexual genetic correlation for fitness, with negative values suggesting conflict. Here, we highlight a potential confounder of this measure-cytoplasmic incompatibility caused by the intracellular parasite Wolbachia. Infection with Wolbachia can generate negative intersexual genetic correlations for fitness in insects, suggestive of intralocus sexual conflict. This is because cytoplasmic incompatibility reduces the fitness of uninfected females mated to infected males, while uninfected males will not suffer reductions in fitness if they mate with infected females and may even be fitter than infected males. This can lead to strong negative intersexual genetic correlations for fitness, mimicking intralocus conflict. We illustrate this issue using simulations and then present Drosophila simulans data that show how reproductive incompatibilities caused by Wolbachia infection can generate signals of intralocus sexual conflict. Given that Wolbachia infection in insect populations is pervasive, but populations usually contain both infected and uninfected individuals providing scope for cytoplasmic incompatibility, this is an important consideration for sexual conflict research but one which, to date, has been largely underappreciated.

RevDate: 2019-01-25

Gruntenko NE, Karpova EK, Adonyeva NV, et al (2019)

Drosophila female fertility and juvenile hormone metabolism depends on the type of Wolbachia infection.

The Journal of experimental biology pii:jeb.195347 [Epub ahead of print].

Maternally inherited intracellular bacteria Wolbachia cause both parasitic and mutualistic effects on their numerous insect hosts that include manipulating the host reproductive system in order to increase the bacteria spreading in a host population, and increasing the host fitness. Here we demonstrate that the type of Wolbachia infection determines the effect on Drosophila melanogaster egg production as a proxy for fecundity and metabolism of juvenile hormone (JH), which acts as gonadotropin in adult insects. For this study we used six D. melanogaster lineages carrying the nuclear background of interbred Bi90 lineage and cytoplasmic backgrounds with Wolbachia of different genotype variants or without it. wMelCS genotype of Wolbachia decreases the egg production in the infected D. melanogaster females in the beginning of oviposion and increases it later (since the sixth day after eclosion), wMelPop Wolbachia strain causes the opposite effect, while wMel, wMel2 and wMel4 genotypes of Wolbachia do not show any effect on these traits compared to uninfected Bi90 D. melanogaster females. The intensity of JH catabolism negatively correlates with the fecundity level in the flies carrying both wMelCS and wMelPop Wolbachia The JH catabolism in females infected with genotypes of wMel group does not differ from that in uninfected females. The effects of wMelCS and wMelPop infection on egg production can be leveled by the modulation of JH titre (via precocene/JH treatment of the flies). Thus, at least one of the mechanisms, promoting the effect of Wolbachia on D. melanogaster female fecundity, is mediated by JH.

RevDate: 2019-01-23

Fallon AM (2019)

Conditions facilitating infection of mosquito cell lines with Wolbachia, an obligate intracellular bacterium.

In vitro cellular & developmental biology. Animal pii:10.1007/s11626-019-00319-6 [Epub ahead of print].

Factors that influence establishment of Wolbachia, an obligate intracellular bacterium, in novel insect hosts or uninfected insect cell lines are poorly understood. Infectivity of Wolbachia strain wStr was correlated with flow cytometric profiles to define optimal conditions for harvesting an infectious inoculum. Wolbachia recovered from the cell culture supernatant after gentle pipetting of infected cells represented about 1% of the total bacterial population and were more infectious than Wolbachia that remained associated with intact cells and/or membranes after low-speed centrifugation. Optimal establishment of a robust infection in naïve cells required 6 d, at a ratio of 80 to 160 bacteria per cell. Among Aedes albopictus mosquito cell lines, an aneuploid line with a 4n + 1 karyotype was more susceptible to infection than diploid lines. These findings contribute to the in vitro manipulation of Wolbachia, illustrate some of the many factors that influence infectivity, and identify areas for future investigation.

RevDate: 2019-01-22

Chebbi MA, Becking T, Moumen B, et al (2019)

The genome of Armadillidium vulgare (Crustacea, Isopoda) provides insights into sex chromosome evolution in the context of cytoplasmic sex determination.

Molecular biology and evolution pii:5298735 [Epub ahead of print].

The terrestrial isopod Armadillidium vulgare is an original model to study the evolution of sex determination and symbiosis in animals. Its sex can be determined by ZW sex chromosomes, or by feminizing Wolbachia bacterial endosymbionts. Here we report the sequence and analysis of the ZW female genome of A. vulgare. A distinguishing feature of the 1.72 gigabase assembly is the abundance of repeats (68% of genome). We show that the Z and W sex chromosomes are essentially undifferentiated at the molecular level and the W-specific region is extremely small (at most several hundreds of kilobases). Our results suggest that recombination suppression has not spread very far from the sex-determining locus, if at all. This is consistent with A. vulgare possessing evolutionarily young sex chromosomes. We characterized multiple Wolbachia nuclear inserts in the A. vulgare genome, none of which is associated with the W-specific region. We also identified several candidate genes that may be involved in the sex determination or sexual differentiation pathways. The A. vulgare genome serves as a resource for studying the biology and evolution of crustaceans, one of the most speciose and emblematic metazoan groups.

RevDate: 2019-01-22

Moreira M, Aguiar AMF, Bourtzis K, et al (2019)

Wolbachia (Alphaproteobacteria: Rickettsiales) Infections in Isolated Aphid Populations from Oceanic Islands of the Azores Archipelago: Revisiting the Supergroups M and N.

Environmental entomology pii:5296035 [Epub ahead of print].

Aphids (Hemiptera: Aphididae) have provided a suitable model to study endosymbionts, their community, and dynamics since the discovery of the obligate endosymbiont Buchnera aphidicola in these organisms. In previous studies, Wolbachia was found in some aphid species. In the present study, we report the prevalence of Wolbachia in aphids sampled from a geographically isolated region (Azores Islands), aiming at a better understanding and characterization of the two newly reported supergroups, M and N. The description of the supergroup M was based on 16S rRNA as well as some protein-coding genes. However, the assignment of the supergroup N was according to 16S rRNA gene sequences of a very few samples. We collected aphid samples and performed phylogenetic analysis of 16S rRNA gene as well as four protein-coding genes (gatB, ftsZ, coxA, and hcpA). The results demonstrate that the 16S rRNA gene data can unambiguously assign the strain supergroup and that the two supergroups, N and M, are equally prevalent in Azorean aphids. The available sequence data for the protein-coding markers can identify supergroup M but the status of supergroup N is inconclusive, requiring further studies. The data suggest that horizontal transmission of Wolbachia (Hertig and Wolbach) between two phylogenetically distant aphid species cohabiting the same plant host.

RevDate: 2019-01-21
CmpDate: 2019-01-21

Ferguson NM (2018)

Challenges and opportunities in controlling mosquito-borne infections.

Nature, 559(7715):490-497.

Mosquito-borne diseases remain a major cause of morbidity and mortality across the tropical regions. Despite much progress in the control of malaria, malaria-associated morbidity remains high, whereas arboviruses-most notably dengue-are responsible for a rising burden of disease, even in middle-income countries that have almost completely eliminated malaria. Here I discuss how new interventions offer the promise of considerable future reductions in disease burden. However, I emphasize that intervention programmes need to be underpinned by rigorous trials and quantitative epidemiological analyses. Such analyses suggest that the long-term goal of elimination is more feasible for dengue than for malaria, even if malaria elimination would offer greater overall health benefit to the public.

RevDate: 2019-01-16

Haqshenas G, Terradas G, Paradkar PN, et al (2019)

A Role for the Insulin Receptor in the Suppression of Dengue Virus and Zika Virus in Wolbachia-Infected Mosquito Cells.

Cell reports, 26(3):529-535.e3.

Wolbachia-infected mosquitoes are refractory to super-infection with arthropod-borne pathogens, but the role of host cell signaling proteins in pathogen-blocking mechanisms remains to be elucidated. Here, we use an antibody microarray approach to provide a comprehensive picture of the signaling response of Aedes aegypti-derived cells to Wolbachia. This approach identifies the host cell insulin receptor as being downregulated by the bacterium. Furthermore, siRNA-mediated knockdown and treatment with a small-molecule inhibitor of the insulin receptor kinase concur to assign a crucial role for this enzyme in the replication of dengue and Zika viruses in cultured mosquito cells. Finally, we show that the production of Zika virus in Wolbachia-free live mosquitoes is impaired by treatment with the selective inhibitor mimicking Wolbachia infection. This study identifies Wolbachia-mediated downregulation of insulin receptor kinase activity as a mechanism contributing to the blocking of super-infection by arboviruses.

RevDate: 2019-01-16

da Silva Gonçalves D, Iturbe-Ormaetxe I, Martins-da-Silva A, et al (2019)

Wolbachia introduction into Lutzomyia longipalpis (Diptera: Psychodidae) cell lines and its effects on immune-related gene expression and interaction with Leishmania infantum.

Parasites & vectors, 12(1):33 pii:10.1186/s13071-018-3227-4.

BACKGROUND: The leishmaniases are important neglected diseases caused by Leishmania spp. which are transmitted by sand flies, Lutzomyia longipalpis being the main vector of visceral leishmaniasis in the Americas. The methodologies for leishmaniasis control are not efficient, causing 1.5 million reported cases annually worldwide, therefore showing the need for development of novel strategies and interventions to control transmission of the disease. The bacterium Wolbachia pipientis is being used to control viruses transmitted by mosquitoes, such as dengue and Zika, and its introduction in disease vectors has been effective against parasites such as Plasmodium. Here we show the first successful establishment of Wolbachia into two different embryonic cell lines from L. longipalpis, LL-5 and Lulo, and analysed its effects on the sand fly innate immune system, followed by in vitro Leishmania infantum interaction.

RESULTS: Our results show that LL-5 cells respond to wMel and wMelPop-CLA strains within the first 72 h post-infection, through the expression of antimicrobial peptides and inducible nitric oxide synthase resulting in a decrease of Wolbachia detection in the early stages of infection. In subsequent passages, the wMel strain was not able to infect any of the sand fly cell lines while the wMelPop-CLA strain was able to stably infect Lulo cells and LL-5 at lower levels. In Wolbachia stably infected cells, the expression of immune-related genes involved with downregulation of the IMD, Toll and Jak-Stat innate immune pathways was significantly decreased, in comparison with the uninfected control, suggesting immune activation upon Wolbachia transinfection. Furthermore, Wolbachia transinfection did not promote a negative effect on parasite load in those cells.

CONCLUSIONS: Initial strong immune responses of LL5 cells might explain the inefficiency of stable infections in these cells while we found that Lulo cells are more permissive to infection with Wolbachia causing an effect on the cell immune system, but not against in vitro L. infantum interaction. This establishes Lulo cells as a good system for the adaptation of Wolbachia in L. longipalpis.

RevDate: 2019-01-15

Shaikevich E, Bogacheva A, L Ganushkina (2019)

Dirofilaria and Wolbachia in mosquitoes (Diptera: Culicidae) in central European Russia and on the Black Sea coast.

Parasite (Paris, France), 26:2.

Dirofilariasis is endemic in Russia, as well as in many other European countries. The aim of this study was to assess the ability of mosquitoes to transfer Dirofilaria immitis and Dirofilaria repens in regions with temperate and subtropical climates. The possible impact of the symbiotic bacterium Wolbachia on Dirofilaria transmission was also investigated. 5333 female mosquitoes were collected at 11 points in central European Russia and on the Black Sea coast during the period 2013-2017. Out of 20 mosquito species examined, 14 were infected with D. repens and 13 with D. immitis. Both species of Dirofilaria were found in different climatic regions. The total Dirofilaria spp. estimated infection rate (EIR) in the central part of Russia varied from 3.1% to 3.7% and, in the southern region, from 1.1% to 3.0%. The highest estimated infection rate was found in Anopheles messeae, the lowest in Culex pipiens. The greatest epidemiological danger was represented by Aedes aegypti, Ae. geniculatus, An. messeae and Ae. communis. Six out of 20 mosquito species were infected with Wolbachia. Pools of Aedes albopictus, Cx. pipiens and Coquillettidia richiardii were simultaneously infected with Dirofilaria and Wolbachia. After checking mosquitoes individually, it was found that there was no development of Dirofilaria to the infective larval stage in specimens infected with Wolbachia. Twenty-two Dirofilaria-infective pools were Wolbachia-free and only two mosquito pools were Wolbachia-infected. The potential for transmission of Dirofilaria in mosquito species naturally uninfected with the symbiotic bacterium Wolbachia is higher than in species infected with the bacterium.

RevDate: 2019-01-15

Foo IJ, Hoffmann AA, PA Ross (2019)

Cross-Generational Effects of Heat Stress on Fitness and Wolbachia Density in Aedes aegypti Mosquitoes.

Tropical medicine and infectious disease, 4(1): pii:tropicalmed4010013.

Aedes aegypti mosquitoes infected with Wolbachia symbionts are now being released into the field to control the spread of pathogenic human arboviruses. Wolbachia can spread throughout vector populations by inducing cytoplasmic incompatibility and can reduce disease transmission by interfering with virus replication. The success of this strategy depends on the effects of Wolbachia on mosquito fitness and the stability of Wolbachia infections across generations. Wolbachia infections are vulnerable to heat stress, and sustained periods of hot weather in the field may influence their utility as disease control agents, particularly if temperature effects persist across generations. To investigate the cross-generational effects of heat stress on Wolbachia density and mosquito fitness, we subjected Ae. aegypti with two different Wolbachia infection types (wMel, wAlbB) and uninfected controls to cyclical heat stress during larval development over two generations. We then tested adult starvation tolerance and wing length as measures of fitness and measured the density of wMel in adults. Both heat stress and Wolbachia infection reduced adult starvation tolerance. wMel Wolbachia density in female offspring was lower when mothers experienced heat stress, but male Wolbachia density did not depend on the rearing temperature of the previous generation. We also found cross-generational effects of heat stress on female starvation tolerance, but there was no cross-generational effect on wing length. Fitness costs of Wolbachia infections and cross-generational effects of heat stress on Wolbachia density may reduce the ability of Wolbachia to invade populations and control arbovirus transmission under specific environmental conditions.

RevDate: 2019-01-11

Öhlund P, Lundén H, AL Blomström (2019)

Insect-specific virus evolution and potential effects on vector competence.

Virus genes pii:10.1007/s11262-018-01629-9 [Epub ahead of print].

The advancement in high-throughput sequencing technology and bioinformatics tools has spurred a new age of viral discovery. Arthropods is the largest group of animals and has shown to be a major reservoir of different viruses, including a group known as insect-specific viruses (ISVs). The majority of known ISVs have been isolated from mosquitoes and shown to belong to viral families associated with animal arbovirus pathogens, such as Flaviviridae, Togaviridae and Phenuiviridae. These insect-specific viruses have a strict tropism and are unable to replicate in vertebrate cells, these properties are interesting for many reasons. One is that these viruses could potentially be utilised as biocontrol agents using a similar strategy as for Wolbachia. Mosquitoes infected with the viral agent could have inferior vectorial capacity of arboviruses resulting in a decrease of circulating arboviruses of public health importance. Moreover, insect-specific viruses are thought to be ancestral to arboviruses and could be used to study the evolution of the switch from single-host to dual-host. In this review, we discuss new discoveries and hypothesis in the field of arboviruses and insect-specific viruses.

RevDate: 2019-01-10

Sazama EJ, Ouellette SP, JS Wesner (2019)

Bacterial Endosymbionts Are Common Among, but not Necessarily Within, Insect Species.

Environmental entomology pii:5280167 [Epub ahead of print].

Bacterial endosymbionts, particularly Wolbachia (Rickettsiales: Rickettsiaceae), Rickettsia (Rickettsiales: Rickettsiaceae), and Cardinium (Bacteroidales: Bacteroidaceae), are commonly found in several arthropod groups, including insects. Most estimates of the global infection rate of Wolbachia (52% [95% credible intervals: 44-60]) show that these bacteria infect more than half of all insect species. Other endosymbionts, such as Rickettsia (24% [confidence intervals [CIs] 20-42]) and Cardinium (13% [CIs 13-55]), infect a smaller but still substantial proportion of insect species. In spite of these observations, it is unclear what proportion of individuals within those species are infected. Here, we used published databases to estimate the proportion of individuals that are infected with either Wolbachia, Rickettsia, or Cardinium. We found that the majority (69%) of Wolbachia-infected species have less than half of their individuals infected with Wolbachia, indicating that although the bacterium may be common among species, it is not common within species. The same was true for Rickettsia (81%) and Cardinium (87%). This discrepancy was consistent across orders, in which less than 10% of individuals were typically infected, even though more than 50% of species within orders were infected. For example, according to our model, nearly 50% of beetle (Coleoptera) species are infected with Wolbachia (i.e., contain at least one individual that has tested positive for Wolbachia), but less than 5% of all individuals are infected. These results add to the growing knowledge base about endosymbionts in insects and should guide future sampling efforts and investigations on the role that these bacteria play in populations.

RevDate: 2019-01-09

Dossi FCA, da Silva EP, FL Cônsoli (2018)

Shifting the Balance: Heat Stress Challenges the Symbiotic Interactions of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera, Liviidae).

The Biological bulletin, 235(3):195-203.

Global warming may impact biodiversity by disrupting biological interactions, including long-term insect-microbe mutualistic associations. Symbiont-mediated insect tolerance to high temperatures is an ecologically important trait that significantly influences an insect's life history. Disruption of microbial symbionts that are required by insects would substantially impact their pest status. Diaphorina citri, a worldwide citrus pest, is associated with the mutualistic symbionts Candidatus Carsonella ruddii and Candidatus Profftella armatura. Wolbachia is also associated with D. citri, but its contribution to the host is unknown. Symbiont density is dependent on a range of factors, including the thermosensitivity of the host and/or symbiont to heat stress. Here, we predicted that short-term heat stress of D. citri would disrupt the host-symbiont phenological synchrony and differentially affect the growth and density of symbionts. We investigated the effects of exposing D. citri eggs to different temperatures for different periods of time on the growth dynamics of symbionts during the nymphal development of D. citri (first instar to fifth instar) by real-time polymerase chain reaction. Symbiont densities were assessed as the number of gene copies, using specific molecular markers: 16S rRNA for Carsonella and Profftella and ftsZ for Wolbachia. Statistical modeling of the copy numbers of symbionts revealed differences in their growth patterns, particularly in the early instars of heat-shocked insects. Wolbachia was the only symbiont to benefit from heat-shock treatment. Although the symbionts responded differently to heat stress, the lack of differences in symbiont densities between treated and control late nymphs suggests the existence of an adaptive genetic process to restore phenological synchrony during the development of immatures in preparation for adult life. Our findings contribute to the understanding of the potential deleterious effects of high temperatures on host-symbiont interactions. Our data also suggest that the effects of host exposure to high temperatures in symbiont growth are highly variable and dependent on the interactions among members of the community of symbionts harbored by a host. Such dependence points to unpredictable consequences for agroecosystems worldwide due to climate change-related effects on the ecological traits of symbiont-dependent insect pests.

RevDate: 2019-01-09

Millán J, Travaini A, Cevidanes A, et al (2019)

Assessing the natural circulation of canine vector-borne pathogens in foxes, ticks and fleas in protected areas of Argentine Patagonia with negligible dog participation.

International journal for parasitology. Parasites and wildlife, 8:63-70 pii:S2213-2244(18)30151-2.

We collected blood and/or ectoparasites from 49 South American grey foxes (Lycalopex griseus) and two Andean foxes (L. culpaeus) caught in two National Parks of southern Argentine Patagonia (Bosques Petrificados, BPNP; and Monte León, MLNP) where dogs are nearly absent (density < 0.01 dog/km2). Common ectoparasites were the flea Pulex irritans (88% prevalence) and the tick Amblyomma tigrinum (29%). Conventional PCR and sequencing of 49 blood samples, 299 fleas analysed in 78 pools, and 21 ticks revealed the presence of DNA of the following canine vector-borne pathogens: in grey foxes, Rickettsia sp. (3%), hemoplasmas (8%), including Mycoplasma haemocanis, and Hepatozoon sp. (50%); in P. irritans, Bartonella spp. (72% of flea pools from 76% of foxes), mostly B. vinsonii subsp. berkhoffii but also B. rochalimae, Anaplasmataceae (Wolbachia sp.; 60% and 54%), and M. haemocanis/haemofelis (29% and 18%); and in A. tigrinum, Hepatozoon sp. (33% of ticks in 4 of 7 foxes). No piroplasmid DNA was detected in any sample. Andean foxes were negative for all tested pathogens. Two different Hepatozoon haplotypes were detected: the most prevalent was phylogenetically associated with H. felis, and the other with H. americanum and related sequences. Amblyomma tigrinum and Hepatozoon sp. were more abundant and/or prevalent in BPNP than in colder MLNP, 300 km southwards, perhaps located close to the limit for tick suitability. Bartonella v. berkhoffii was also significantly more prevalent in fleas of foxes in BPNP than in MLNP. This study provides novel information about natural host-pathogen associations in wildlife, markedly extends the distribution area in South America of arthropods and vector-borne pathogens of veterinary and public health interest, and contributes preliminary evidence about the potential role of A. tigrinum and P. irritans as vectors, respectively, for potentially new species of Hepatozoon from Lycalopex spp. and for M. haemocanis that should be further investigated.

RevDate: 2019-01-09

Kirichenko N, Triberti P, Kobayashi S, et al (2018)

Systematics of Phyllocnistis leaf-mining moths (Lepidoptera, Gracillariidae) feeding on dogwood (Cornus spp.) in Northeast Asia, with the description of three new species.


During an ongoing DNA-barcoding campaign of the leaf-mining moths that feed on woody plants in Northeast Asia, four lineages of the genus Phyllocnistis (Gracillariidae, Phyllocnistinae) were discovered on dogwood (Cornus spp): P. cornella Ermolaev, 1987 on C. controversa Hemsl. (Japan: Hokkaido) and three new species - one feeding on C. controversa, C. florida L. and C. macrophylla Wall. in Japan (Honshu, Shikoku, Kyushu), a second species on C. macrophylla in China (Yunnan) and a third on Siberian dogwood Cornus alba L. in Russia (Siberia). All these species showed differences in morphology, in the barcode region of the cytochrome c oxidase I gene and in two nuclear genes (histone H3 and 28S ribosomal RNA). No correlation was found between the deep mitochondrial splits observed and the Wolbachia infection pattern. Based on both morphological and molecular evidence, the three recently discovered lineages are described here as new species: P. indistincta Kobayashi & Triberti, sp. n. (Japan), P. saepta Kirichenko, Ohshima & Huang, sp. n. (China) and P. verae Kirichenko, Triberti & Lopez-Vaamonde, sp. n. (Russia). In addition, the authors re-describe the adult morphology of P. cornella, provide the first record of this species from Japan and highlight the diagnostic characters that allow these Cornus-feeding Phyllocnistis species to be distinguished.

RevDate: 2019-01-08

Garcia GA, Sylvestre G, Aguiar R, et al (2019)

Matching the genetics of released and local Aedes aegypti populations is critical to assure Wolbachia invasion.

PLoS neglected tropical diseases, 13(1):e0007023 pii:PNTD-D-18-01360 [Epub ahead of print].

BACKGROUND: Traditional vector control approaches such as source reduction and insecticide spraying have limited effect on reducing Aedes aegypti population. The endosymbiont Wolbachia is pointed as a promising tool to mitigate arbovirus transmission and has been deployed worldwide. Models predict a rapid increase on the frequency of Wolbachia-positive Aedes aegypti mosquitoes in local settings, supported by cytoplasmic incompatibility (CI) and high maternal transmission rate associated with the wMelBr strain.

Wolbachia wMelBr strain was released for 20 consecutive weeks after receiving >87% approval of householders of the isolated community of Tubiacanga, Rio de Janeiro. wMelBr frequency plateued~40% during weeks 7-19, peaked 65% but dropped as releases stopped. A high (97.56%) maternal transmission was observed. Doubling releases and deploying mosquitoes with large wing length and low laboratory mortality produced no detectable effects on invasion trend. By investigating the lab colony maintenance procedures backwardly, pyrethroid resistant genotypes in wMelBr decreased from 68% to 3.5% after 17 generations. Therefore, we initially released susceptible mosquitoes in a local population highly resistant to pyrethroids which, associated with the over use of insecticides by householders, ended jeopardizing Wolbachia invasion. A new strain (wMelRio) was produced after backcrossing wMelBr females with males from field to introduce mostly pyrethroid resistance alleles. The new strain increased mosquito survival but produced relevant negative effects on Ae. aegypti fecundity traits, reducing egg clutche size and egg hatch. Despite the cost on fitness, wMelRio successful established where wMelBr failed, revealing that matching the local population genetics, especially insecticide resistance background, is critical to achieve invasion.

CONCLUSIONS/SIGNIFICANCE: Local householders support was constantly high, reaching 90% backing on the second release (wMelRio strain). Notwithstanding the drought summer, the harsh temperature recorded (daily average above 30°C) did not seem to affect the expression of maternal transmission of wMel on a Brazilian background. Wolbachia deployment should match the insecticide resistance profile of the wild population to achieve invasion. Considering pyrethroid-resistance is a widely distributed phenotype in natural Ae. aegypti populations, future Wolbachia deployments must pay special attention in maintaining insecticide resistance in lab colonies for releases.

RevDate: 2019-01-08

Hong WD, Benayoud F, Nixon GL, et al (2019)

AWZ1066S, a highly specific anti-Wolbachia drug candidate for a short-course treatment of filariasis.

Proceedings of the National Academy of Sciences of the United States of America pii:1816585116 [Epub ahead of print].

Onchocerciasis and lymphatic filariasis are two neglected tropical diseases that together affect ∼157 million people and inflict severe disability. Both diseases are caused by parasitic filarial nematodes with elimination efforts constrained by the lack of a safe drug that can kill the adult filaria (macrofilaricide). Previous proof-of-concept human trials have demonstrated that depleting >90% of the essential nematode endosymbiont bacterium, Wolbachia, using antibiotics, can lead to permanent sterilization of adult female parasites and a safe macrofilaricidal outcome. AWZ1066S is a highly specific anti-Wolbachia candidate selected through a lead optimization program focused on balancing efficacy, safety and drug metabolism/pharmacokinetic (DMPK) features of a thienopyrimidine/quinazoline scaffold derived from phenotypic screening. AWZ1066S shows superior efficacy to existing anti-Wolbachia therapies in validated preclinical models of infection and has DMPK characteristics that are compatible with a short therapeutic regimen of 7 days or less. This candidate molecule is well-positioned for onward development and has the potential to make a significant impact on communities affected by filariasis.

RevDate: 2019-01-05

Bustamante-Brito R, Vera-Ponce de León A, Rosenblueth M, et al (2019)

Metatranscriptomic Analysis of the Bacterial Symbiont Dactylopiibacterium carminicum from the Carmine Cochineal Dactylopius coccus (Hemiptera: Coccoidea: Dactylopiidae).

Life (Basel, Switzerland), 9(1): pii:life9010004.

The scale insect Dactylopius coccus produces high amounts of carminic acid, which has historically been used as a pigment by pre-Hispanic American cultures. Nowadays carmine is found in food, cosmetics, and textiles. Metagenomic approaches revealed that Dactylopius spp. cochineals contain two Wolbachia strains, a betaproteobacterium named Candidatus Dactylopiibacterium carminicum and Spiroplasma, in addition to different fungi. We describe here a transcriptomic analysis indicating that Dactylopiibacterium is metabolically active inside the insect host, and estimate that there are over twice as many Dactylopiibacterium cells in the hemolymph than in the gut, with even fewer in the ovary. Albeit scarce, the transcripts in the ovaries support the presence of Dactylopiibacterium in this tissue and a vertical mode of transmission. In the cochineal, Dactylopiibacterium may catabolize plant polysaccharides, and be active in carbon and nitrogen provisioning through its degradative activity and by fixing nitrogen. In most insects, nitrogen-fixing bacteria are found in the gut, but in this study they are shown to occur in the hemolymph, probably delivering essential amino acids and riboflavin to the host from nitrogen substrates derived from nitrogen fixation.

RevDate: 2019-01-03

Clare RH, Bardelle C, Harper P, et al (2019)

Industrial scale high-throughput screening delivers multiple fast acting macrofilaricides.

Nature communications, 10(1):11 pii:10.1038/s41467-018-07826-2.

Nematodes causing lymphatic filariasis and onchocerciasis rely on their bacterial endosymbiont, Wolbachia, for survival and fecundity, making Wolbachia a promising therapeutic target. Here we perform a high-throughput screen of AstraZeneca's 1.3 million in-house compound library and identify 5 novel chemotypes with faster in vitro kill rates (<2 days) than existing anti-Wolbachia drugs that cure onchocerciasis and lymphatic filariasis. This industrial scale anthelmintic neglected tropical disease (NTD) screening campaign is the result of a partnership between the Anti-Wolbachia consortium (A∙WOL) and AstraZeneca. The campaign was informed throughout by rational prioritisation and triage of compounds using cheminformatics to balance chemical diversity and drug like properties reducing the chance of attrition from the outset. Ongoing development of these multiple chemotypes, all with superior time-kill kinetics than registered antibiotics with anti-Wolbachia activity, has the potential to improve upon the current therapeutic options and deliver improved, safer and more selective macrofilaricidal drugs.

RevDate: 2018-12-31

Fortin M, Vitet C, Souty-Grosset C, et al (2018)

How do familiarity and relatedness influence mate choice in Armadillidium vulgare?.

PloS one, 13(12):e0209893 pii:PONE-D-18-05472.

Mate choice is an important process in sexual selection and usually prevents inbreeding depression in populations. In the terrestrial isopod Armadillidium vulgare, the close physical proximity between individuals may increase the risk of reproducing with siblings. Moreover, individuals of this species can be infected with the feminizing bacteria of Wolbachia, which influence male mate choice. However, little is known about the kinship or familiarity assessment of the selected partner that occurs when a male can choose between females with or without Wolbachia. To investigate the potential mechanisms leading to mate choice and the potential impact of the parasite, we performed behavioral choice tests on males where they could choose between sibling vs. nonsibling females, familiar vs. unfamiliar females, and sibling familiar vs. unfamiliar nonsibling females. To investigate the costs of inbreeding, we compared the reproductive success of both sibling and nonsibling mates. Our results revealed that male copulation attempts were higher for familiar females and for nonsibling females when both females were Wolbachia-infected, but the duration was longer when both females were Wolbachia-free. When males mated with a sibling female, their fecundity was severely decreased, consistent with inbreeding depression. Overall, we observed copulations with all types of females and demonstrated discrimination capacities and potential preferences. We highlight the complexity of the tradeoff between kinship, familiarity and parasite transmission assessment for mate choice.

RevDate: 2018-12-31

O'Neill SL, Ryan PA, Turley AP, et al (2018)

Scaled deployment of Wolbachia to protect the community from dengue and other Aedes transmitted arboviruses.

Gates open research, 2:36.

Background: A number of new technologies are under development for the control of mosquito transmitted viruses, such as dengue, chikungunya and Zika that all require the release of modified mosquitoes into the environment. None of these technologies has been able to demonstrate evidence that they can be implemented at a scale beyond small pilots. Here we report the first successful citywide scaled deployment of Wolbachia in the northern Australian city of Townsville. Methods: The wMel strain of Wolbachia was backcrossed into a local Aedes aegypti genotype and mass reared mosquitoes were deployed as eggs using mosquito release containers (MRCs). In initial stages these releases were undertaken by program staff but in later stages this was replaced by direct community release including the development of a school program that saw children undertake releases. Mosquito monitoring was undertaken with Biogents Sentinel (BGS) traps and individual mosquitoes were screened for the presence of Wolbachia with a Taqman qPCR or LAMP diagnostic assay. Dengue case notifications from Queensland Health Communicable Disease Branch were used to track dengue cases in the city before and after release. Results: Wolbachia was successfully established into local Ae. aegypti mosquitoes across 66 km in four stages over 28 months with full community support. A feature of the program was the development of a scaled approach to community engagement. Wolbachia frequencies have remained stable since deployment and to date no local dengue transmission has been confirmed in any area of Townsville after Wolbachia has established, despite local transmission events every year for the prior 13 years and an epidemiological context of increasing imported cases. Conclusion: Deployment of Wolbachia into Ae. aegypti populations can be readily scaled to areas of ~60km quickly and cost effectively and appears in this context to be effective at stopping local dengue transmission.

RevDate: 2018-12-31

Gangwar M, Jha R, Goyal M, et al (2018)

Immunogenicity and protective efficacy of Recombinase A from Wolbachia endosymbiont of filarial nematode Brugia malayi (wBmRecA).

Vaccine pii:S0264-410X(18)31675-X [Epub ahead of print].

Lymphatic filariasis causes global morbidity. Wolbachia, an endo-symbiotic intracellular bacterium of the filarial nematode helps in their growth and development, regulates fecundity in female worms and contributes to the immunopathogenesis of the disease. However, genes and proteins of Wolbachia that may act as putative vaccine candidates are not known. In this study, we cloned recombinase-A protein of Wolbachia from Brugia malayi (wBmRecA) and carried out its detailed biochemical and immunological characterization. Bioinformatics analysis, circular dichroism and fluorescence spectral studies showed significant sequence and structural similarities between wBmRecA and RecA of other alpha-proteo- bacterial species. wBmRecA was ubiquitously expressed in all the three major life stages of B. malayi, including excretory-secretory products of the adult worm. In silico studies suggested immunogenic potential of wBmRecA, and mice immunized with wBmRecA exhibited elevated levels of immunoglobulins IgG1, IgG2a, IgG2b and IgG3 in their serum along with increased percentages of CD4+, CD8+ T cells and CD19+ B cells in their spleens. Notably, splenocytes from immunized mice showed increased m-RNA expression of T-bet, elevated proinflammatory cytokines IFN-γ and IL-12, while peritoneal MФs exhibited increased levels of iNOS, downregulated Arg-1 and secreted copious amounts of nitric oxide which contributed to severely impaired development of the infective larvae (Bm-L3). Interestingly, sera from immunized mice promoted significant cellular adherence and cytotoxicity against microfilariae and Bm-L3. Importantly, wBmRecA demonstrated strong immuno-reactivity with bancroftian sera from endemic normal individuals. These results suggest that wBmRecA is highly immunogenic, and should be explored further as a putative vaccine candidate against lymphatic filariasis.

RevDate: 2018-12-27

Savadelis MD, Day KM, Bradner JL, et al (2018)

Efficacy and side effects of doxycycline versus minocycline in the three-dose melarsomine canine adulticidal heartworm treatment protocol.

Parasites & vectors, 11(1):671 pii:10.1186/s13071-018-3264-z.

BACKGROUND: The American Heartworm Society currently recommends the use of a monthly macrocyclic lactone, a 28-day course of 10 mg/kg doxycycline BID, and the 3-dose protocol of melarsomine dihydrochloride for the treatment of canine heartworm disease. Doxycycline is necessary for the reduction of the bacterium Wolbachia, found in all heartworm life-stages. Previous price increases and decreasing availability prompted us to evaluate alternative tetracycline antibiotics, i.e. minocycline, for the reduction of Wolbachia during canine heartworm treatment.

METHODS: Thirty-two heartworm-positive dogs were randomized to receive 10 mg/kg or 5 mg/kg of either doxycycline or minocycline for 28 days BID, for a total of 8 dogs per experimental group. All dogs received 6 months of Heartgard Plus® (ivermectin/pyrantel) and the 3-dose protocol of 2.5 mg/kg melarsomine dihydrochloride. Blood samples were collected prior to the initiation of treatment, every 7 days throughout tetracycline treatment, and then monthly thereafter until the dog tested negative for the presence of heartworm antigen. DNA was isolated from circulating microfilarial samples and qPCR was performed on each sample.

RESULTS: A greater number of dogs in the 10 mg/kg doxycycline and minocycline treated groups experienced gastrointestinal side effects as compared to the 5 mg/kg doxycycline and minocycline treated groups. All eight dogs in the 10 mg/kg doxycycline-treated group tested negative for the presence of Wolbachia DNA by 28 days post-tetracycline treatment. A total of two dogs in both the 5 mg/kg doxycycline- and 10 mg/kg minocycline-treated groups and three dogs in the 5 mg/kg minocycline-treated group remained positive for the presence of Wolbachia DNA by the end of tetracycline treatment.

CONCLUSIONS: No lung pathology was assessed in this clinical trial, therefore the clinical effect of the remaining Wolbachia DNA in the 10 mg/kg minocycline-, 5 mg/kg doxycycline- and 5 mg/kg minocycline-treated groups cannot be determined. Owner compliance in the proper administration of these tetracyclines may be impacted by the increased severe gastrointestinal side effects reported for the 10 mg/kg doxycycline- and minocycline-treated groups. We recommend that veterinarians prescribe the recommended 10 mg/kg doxycycline for canine heartworm treatment and reduce the dosage to 5 mg/kg in cases of severe gastrointestinal side effects in order to improve owner compliance in administration of medications.

RevDate: 2018-12-26

Altinli M, Soms J, Ravallec M, et al (2018)

Sharing cells with Wolbachia: The transovarian vertical transmission of Culex pipiens densovirus.

Environmental microbiology [Epub ahead of print].

Culex pipiens densovirus (CpDV), a single stranded DNA virus, has been isolated from Culex pipiens mosquitoes but differs from other mosquito densoviruses in terms of genome structure and sequence identity. Its transmission from host to host, the nature of its interactions with both its host and host's endosymbiotic bacteria Wolbachia are not known. Here we report the presence of CpDV in the ovaries and eggs of Cx. pipiens mosquitoes in close encounters with Wolbachia. In the ovaries, CpDV amount significantly differed between mosquito lines harboring different strains of Wolbachia and these differences were not linked to variations in Wolbachia densities. CpDV was vertically transmitted in all laboratory lines to 17%-20% of the offspring. For some females, however, the vertical transmission reached 90%. Antibiotic treatment that cured the host from Wolbachia significantly decreased both CpDV quantity and vertical transmission suggesting an impact of host microbiota, including Wolbachia, on CpDV transmission. Overall our results show that CpDV is transmitted vertically via transovarian path along with Wolbachia with which it shares the same cells. Our results are primordial to understand the dynamics of densovirus infection, their persistence and spread in populations considering their potential use in the regulation of mosquito vector populations. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-25

Kittayapong P, Kaeothaisong NO, Ninphanomchai S, et al (2018)

Combined sterile insect technique and incompatible insect technique: sex separation and quality of sterile Aedes aegypti male mosquitoes released in a pilot population suppression trial in Thailand.

Parasites & vectors, 11(Suppl 2):657 pii:10.1186/s13071-018-3214-9.

BACKGROUND: The sterile insect technique (SIT), which is based on irradiation-induced sterility, and incompatible insect technique (IIT), which is based on Wolbachia-induced cytoplasmic incompatibility (a kind of male sterility), have been used as alternative methods to reduce mosquito vector populations. Both methods require the release of males to reduce fertile females and suppress the number of natural populations. Different techniques of sex separation to obtain only males have been investigated previously. Our work involves an application of mechanical larval-pupal glass separators to separate Wolbachia-infected Aedes aegypti males from females at the pupal stage, prior to irradiation, and for use in a pilot field release and to assess the quality of males and females before and after sex separation and sterilization.

RESULTS: This study was the first to demonstrate the efficiency of mechanical glass separators in separating males for use in an Ae. aegypti suppression trial by a combined SIT/IIT approach. Our results indicated that male and female pupae of Wolbachia-infected Ae. aegypti mosquitoes were significantly different (p < 0.05) in weight, size, and emergence-time, which made it easier for sex separation by this mechanical method. During the pilot field release, the percentage of female contamination was detected to be quite low and significantly different between the first (0.10 ± 0.13) and the second (0.02 ± 0.02) twelve-week period. Both males and females were almost completely sterile after exposure to 70 Gy irradiation dose. We observed that both irradiated Wolbachia-infected males and females survived and lived longer than two weeks, but males could live longer than females (p < 0.05) when they were irradiated at the same irradiation dose. When comparing irradiated mosquitoes with non-irradiated ones, there was no significant difference in longevity and survival-rate between those males, but non-irradiated females lived longer than irradiated ones (p < 0.05).

CONCLUSION: Mechanical sex separation by using a larval-pupal glass separator was practically applied to obtain only males for further sterilization and open field release in a pilot population suppression trial of Ae. aegypti in Thailand. Female contamination was detected to be quite low, and skilled personnel can reduce the risk for female release. The irradiated Wolbachia-infected females accidentally released were found to be completely sterile, with shorter life span than males.

RevDate: 2018-12-25

Moretti R, Marzo GA, Lampazzi E, et al (2018)

Cytoplasmic incompatibility management to support Incompatible Insect Technique against Aedes albopictus.

Parasites & vectors, 11(Suppl 2):649 pii:10.1186/s13071-018-3208-7.

BACKGROUND: The transinfection of the endosymbiotic bacterium Wolbachia provides a method to produce functionally sterile males to be used to suppress mosquito vectors. ARwP is a wPip Wolbachia infected Aedes albopictus which exhibits a bidirectional incompatibility pattern with wild-types. We coupled a modelistic approach with laboratory experiments to test ARwP as a control tool and evaluate the possible occurrence of population replacement following the release of ARwP females in a wild-type (SANG) population. Repeated male-only releases were simulated and tested in the laboratory in comparison with releases contaminated with 1% ARwP females. Model simulations also investigated how migration affects the outcome of contaminated releases. Finally, the mean level of egg fertility and the long-term evolution of populations constituted by two Wolbachia infection types were studied by testing SANG and ARwP Ae. albopictus and performing more general model simulations.

RESULTS: The model was parametrized with laboratory data and simulations were compared with results of biological trials. Small populations of ARwP males and females were theoretically and experimentally demonstrated to rapidly become extinct when released in larger SANG populations. Male-only releases at a 5:1 ratio with respect to the wild-type males led to a complete suppression of the SANG population in a few generations. Contaminated releases were efficient as well but led to population replacement in the long term, when the wild-type population approached eradication. Migration significantly contrasted this trend as a 5% population turnover was sufficient to avoid any risk of population replacement. At equal frequencies between ARwP and SANG individuals, the mean egg fertility of the overall population was more than halved and suppression was self-sustaining until one of the two infection types extinguished.

CONCLUSIONS: In the case of bidirectional incompatibility patterns, the repeated release of incompatible males with small percentages of contaminant females could lead to population replacement in confined environments while it could be managed to target high efficiency and sustainability in wild-type suppression when systems are open to migration. This possibility is discussed based on various contexts and taking into consideration the possibility of integration with other control methods such as SIT and the use of larvicides.

RevDate: 2018-12-24

Parry R, Bishop C, De Hayr L, et al (2018)

Density-dependent enhanced replication of a densovirus in Wolbachia-infected Aedes cells is associated with production of piRNAs and higher virus-derived siRNAs.

Virology, 528:89-100 pii:S0042-6822(18)30370-2 [Epub ahead of print].

The endosymbiotic bacterium Wolbachia pipientis has been shown to restrict a range of RNA viruses in Drosophila melanogaster and transinfected dengue mosquito, Aedes aegypti. Here, we show that Wolbachia infection enhances replication of Aedes albopictus densovirus (AalDNV-1), a single stranded DNA virus, in Aedes cell lines in a density-dependent manner. Analysis of previously produced small RNAs of Aag2 cells showed that Wolbachia-infected cells produced greater absolute abundance of virus-derived short interfering RNAs compared to uninfected cells. Additionally, we found production of virus-derived PIWI-like RNAs (vpiRNA) produced in response to AalDNV-1 infection. Nuclear fractions of Aag2 cells produced a primary vpiRNA signature U1 bias whereas the typical "ping-pong" signature (U1 - A10) was evident in vpiRNAs from the cytoplasmic fractions. This is the first report of the density-dependent enhancement of DNA viruses by Wolbachia. Further, we report the generation of vpiRNAs in a DNA virus-host interaction for the first time.

RevDate: 2018-12-24

Elias-Costa AJ, Confalonieri VA, Lanteri AA, et al (2018)

Game of Clones: Is Wolbachia inducing speciation in a weevil with a mixed reproductive mode?.

Molecular phylogenetics and evolution pii:S1055-7903(17)30662-0 [Epub ahead of print].

Parthenogenesis is widely distributed in Metazoa but it is especially frequent in weevils (Coleoptera, Curculionidae) with one fifth of all known cases. Previous studies have shown that in the tribe Naupactini parthenogenetic reproduction most likely originated with an infection of the endoparasitic bacterium Wolbachia pipientis. In particular, Pantomorus postfasciatus possess a mixed reproductive mode: some populations have males while in others they are absent, and females produce clones by thelytoky. To better understand this scenario, we studied the population structure and infection status in 64 individuals of P. postfasciatus from Argentina and Brazil. We sequenced two mitochondrial (COI and COII) and one nuclear (ITS-1) fragments and obtained two very divergent haplogroups, one corresponding to the sexual populations uninfected with Wolbachia, and another conforming a monophyletic parthenogenetic (or presumptively parthenogenetic) and infected clade. Each of these haplogroups was identified as an independently evolutionary unit by all species delimitation analyses accomplished: multilocus *BEAST and BP&P, and single locus GMYC and K/θ rule. Additionally, present evidence suggests that Wolbachia infection occurred at least twice in all-female populations of P. postfasciatus with two different bacterial strains. Speciation mediated by Wolbachia is a recently described phenomenon and the case of P. postfasciatus is the first known case in a diplo-diploid insect. A model that describes how thelytoky-inducing phenotypes of Wolbachia could generate new lineages is discussed.

RevDate: 2018-12-24

Niang EHA, Bassene H, Fenollar F, et al (2018)

Biological Control of Mosquito-Borne Diseases: The Potential of Wolbachia-Based Interventions in an IVM Framework.

Journal of tropical medicine, 2018:1470459.

People living in the tropical and subtropical regions of the world face an enormous health burden due to mosquito-borne diseases such as malaria, dengue fever, and filariasis. Historically and today, targeting mosquito vectors with, primarily, insecticide-based control strategies have been a key control strategy against major mosquito-borne diseases. However, the success to date of such approaches is under threat from multiple insecticide resistance mechanisms while vector control (VC) options are still limited. The situation therefore requires the development of innovative control measures against major mosquito-borne diseases. Transinfecting mosquitos with symbiotic bacteria that can compete with targeted pathogens or manipulate host biology to reduce their vectorial capacity are a promising and innovative biological control approach. In this review, we discuss the current state of knowledge about the association between mosquitoes and Wolbachia, emphasizing the limitations of different mosquito control strategies and the use of mosquitoes' commensal microbiota as innovative approaches to control mosquito-borne diseases.

RevDate: 2018-12-19

Martínez-Rodríguez P, JL Bella (2018)

Chorthippus parallelus and Wolbachia: Overlapping Orthopteroid and Bacterial Hybrid Zones.

Frontiers in genetics, 9:604.

Wolbachia is a well-known endosymbiotic, strictly cytoplasmic bacterium. It establishes complex cytonuclear relations that are not necessarily deleterious to its host, but that often result in reproductive alterations favoring bacterial transmission. Among these alterations, a common one is the cytoplasmic incompatibility (CI) that reduces the number of descendants in certain crosses between infected and non-infected individuals. This CI induced by Wolbachia appears in the hybrid zone that the grasshoppers Chorthippus parallelus parallelus (Cpp) and C. p. erythropus (Cpe) form in the Pyrenees: a reputed model in evolutionary biology. However, this cytonuclear incompatibility is the result of sophisticated processes of the co-divergence of the genomes of the bacterial strains and the host after generations of selection and coevolution. Here we show how these genome conflicts have resulted in a finely tuned adjustment of the bacterial strain to each pure orthopteroid taxon, and the striking appearance of another, newly identified recombinant Wolbachia strain that only occurs in hybrid grasshoppers. We propose the existence of two superimposed hybrid zones: one organized by the grasshoppers, which overlaps with a second, bacterial hybrid zone. The two hybrid zones counterbalance one another and have evolved together since the origin of the grasshopper's hybrid zone.

RevDate: 2018-12-19
CmpDate: 2018-12-19

Palmer WH, Medd NC, Beard PM, et al (2018)

Isolation of a natural DNA virus of Drosophila melanogaster, and characterisation of host resistance and immune responses.

PLoS pathogens, 14(6):e1007050.

Drosophila melanogaster has played a key role in our understanding of invertebrate immunity. However, both functional and evolutionary studies of host-virus interaction in Drosophila have been limited by a dearth of native virus isolates. In particular, despite a long history of virus research, DNA viruses of D. melanogaster have only recently been described, and none have been available for experimental study. Here we report the isolation and comprehensive characterisation of Kallithea virus, a large double-stranded DNA virus, and the first DNA virus to have been reported from wild populations of D. melanogaster. We find that Kallithea virus infection is costly for adult flies, reaching high titres in both sexes and disproportionately reducing survival in males, and movement and late fecundity in females. Using the Drosophila Genetic Reference Panel, we quantify host genetic variance for virus-induced mortality and viral titre and identify candidate host genes that may underlie this variation, including Cdc42-interacting protein 4. Using full transcriptome sequencing of infected males and females, we examine the transcriptional response of flies to Kallithea virus infection and describe differential regulation of virus-responsive genes. This work establishes Kallithea virus as a new tractable model to study the natural interaction between D. melanogaster and DNA viruses, and we hope it will serve as a basis for future studies of immune responses to DNA viruses in insects.

RevDate: 2018-12-18

Maleki-Ravasan N, Akhavan N, Raz A, et al (2018)

Co-occurrence of pederin-producing and Wolbachia endobacteria in Paederus fuscipes Curtis, 1840 (Coleoptera: Staphilinidae) and its evolutionary consequences.

MicrobiologyOpen [Epub ahead of print].

The dual occurrence of Pseudomonas-like and Wolbachia endobacteria has not been investigated in the Pederus beetles yet. We investigated pederin-producing bacteria (PPB) infection in Paederus fuscipes specimens from the southern margins of the Caspian Sea by designed genus-specific (OprF) and species-specific (16S rRNA) primers. Wolbachia infection was studied through a nested-PCR assay of Wolbachia surface protein (wsp) gene. Of the 125 analyzed beetles, 42 females (82.35%) and 15 males (20.27%) were positive to PPB infection; this is the first study reporting male P. fuscipes infection to PPB. Wolbachia infection was found in 45 female (88.23%) and 50 male (67.57%) analyzed beetles. Surprisingly, a number of 36 females (70.59%) and 13 males (17.57%) were found to be infected with both PPB and Wolbachia endosymbionts. In general, population infection rates to PPB and Wolbachia were determined to be 45.6% and 76%, respectively. The infection rates of female beetles to PPB and PPB-Wolbachia were significantly higher than males. In Paederus species, only female beetles shelter PPB and the discovery of this bacterium in adult males may reflect their cannibalistic behavior on the contaminated stages. Phylogenetic analysis showed that the sequences of OprF gene were unique among Pseudomonas spp.; however, sequences of 16S rRNA gene were related to the PPB of Pederus species. The co-occurrence and random distribution of these endobacteria may imply putative tripartite interactions among PPB, Wolbachia, and Paederus. In order to elucidate these possible tripartite interactions, further studies are required even at gender level.

RevDate: 2018-12-15

Asselin AK, Villegas-Ospina S, Hoffmann AA, et al (2018)

Contrasting patterns of virus protection and functional incompatibility genes in two conspecific Wolbachia strains from Drosophila pandora.

Applied and environmental microbiology pii:AEM.02290-18 [Epub ahead of print].

Wolbachia infections can present different phenotypes in hosts, including different forms of reproductive manipulation and antiviral protection, which may influence infection dynamics within host populations. In populations of Drosophila pandora two distinct Wolbachia strains co-exist, each manipulating host reproduction: wPanCI, causes cytoplasmic incompatibility (CI), whereas wPanMK, causes male-killing (MK). CI occurs when a Wolbachia-infected male mates with a female not infected with a compatible type of Wolbachia, leading to non-viable offspring. wPanMK can rescue wPanCI-induced CI but is unable to induce CI. The antiviral protection phenotypes provided by the wPanCI and wPanMK infections were characterised; strains showed differential protection phenotypes whereby cricket paralysis virus (CrPV)-induced mortality was delayed in flies infected with wPanMK but enhanced in flies with wPanCI when compared to their respective Wolbachia-cured counterparts. Homologs of cifA and cifB genes involved in CI identified in wPanMK and wPanCI showed a high degree of conservation; however, the cifB protein in wPanMK is truncated and is likely non-functional. The presence of a likely functional cifA in wPanMK, and wPanMK's ability to rescue wPanCI-induced CI is consistent with the recent confirmation of cifA's involvement in CI rescue; and the absence of a functional cifB protein further supports its involvement as a CI modification factor. Taken together these findings indicate that wPanCI and wPanMK have different relationships with their hosts in terms of their protective and CI phenotypes. It is therefore likely that different factors influence the prevalence and dynamics of these co-infections in natural D. pandora hosts.ImportanceWolbachia strains are common endosymbionts in insects with multiple strains often coexisting in the same species. The coexistence of multiple strains is poorly understood but may rely on Wolbachia having diverse phenotypic effects on their hosts. As Wolbachia is increasingly being developed as a tool to control disease transmission and suppress pest populations, it is important to understand the ways in which multiple Wolbachia strains persist in natural populations and how these might then be manipulated. We have therefore investigated viral protection and the molecular basis of cytoplasmic incompatibility in two coexisting Wolbachia strains with contrasting effects on host reproduction.

RevDate: 2018-12-14

Hellemans S, Kaczmarek N, Marynowska M, et al (2018)

Bacteriome-associated Wolbachia of the parthenogenetic termite Cavitermes tuberosus.

FEMS microbiology ecology pii:5247714 [Epub ahead of print].

Wolbachia has deeply shaped the ecology and evolution of many arthropods, and interactions between the two partners are a continuum ranging from parasitism to mutualism. Non-dispersing queens of the termite Cavitermes tuberosus are parthenogenetically produced through gamete duplication, a mode of ploidy restoration generally induced by Wolbachia. These queens display a bacteriome-like structure in the anterior part of the mesenteron. Our study explores the possibility of a nutritional mutualistic, rather than a parasitic, association between Wolbachia and C. tuberosus. We found a unique strain (wCtub), nested in the supergroup F, in 28 nests collected in French Guiana, the island of Trinidad and the state of Paraíba, Brazil (over 3,500 km). wCtub infects individuals regardless of caste, sex or reproductive (sexual versus parthenogenetic) origin. qPCR assays reveal that Wolbachia densities are higher in the bacteriome-like structure and in the surrounding gut compared to other somatic tissues. High-throughput 16S rRNA gene amplicon sequencing reveals that Wolbachia represents over 97% of bacterial reads present in the bacteriome structure. BLAST analyses of 16S rRNA, bioA (a gene of the biosynthetic pathway of B vitamins) and five MLST genes indicated that wCtub shares 99% identity with wCle, an obligate nutritional mutualist of the bedbug Cimex lectularius.

RevDate: 2018-12-14

Baldini F, Rougé J, Kreppel K, et al (2018)

First report of natural Wolbachia infection in the malaria mosquito Anopheles arabiensis in Tanzania.

Parasites & vectors, 11(1):635 pii:10.1186/s13071-018-3249-y.

BACKGROUND: Natural infections of the endosymbiont bacteria Wolbachia have recently been discovered in populations of the malaria mosquito Anopheles gambiae (s.l.) in Burkina Faso and Mali, West Africa. This Anopheles specific strain wAnga limits the malaria parasite Plasmodium falciparum infections in the mosquito, thus it offers novel opportunities for malaria control.

RESULTS: We investigated Wolbachia presence in Anopheles arabiensis and Anopheles funestus, which are the two main malaria vectors in the Kilombero Valley, a malaria endemic region in south-eastern Tanzania. We found 3.1% (n = 65) and 7.5% (n = 147) wAnga infection prevalence in An. arabiensis in mosquitoes collected in 2014 and 2016, respectively, while no infection was detected in An. funestus (n = 41). Phylogenetic analysis suggests that at least two distinct strains of wAnga were detected, both belonging to Wolbachia supergroup A and B.

CONCLUSIONS: To our knowledge, this is the first confirmation of natural Wolbachia in malaria vectors in Tanzania, which opens novel questions on the ecological and genetic basis of its persistence and pathogen transmission in the vector hosts. Understanding the basis of interactions between Wolbachia, Anopheles mosquitoes and malaria parasites is crucial for investigation of its potential application as a biocontrol strategy to reduce malaria transmission, and assessment of how natural wAnga infections influence pathogen transmission in different ecological settings.

RevDate: 2018-12-13

Kanté ST, Melachio T, Ofon E, et al (2018)

Detection of Wolbachia and different trypanosome species in Glossina palpalis palpalis populations from three sleeping sickness foci of southern Cameroon.

Parasites & vectors, 11(1):630 pii:10.1186/s13071-018-3229-2.

BACKGROUND: African trypanosomiases are caused by trypanosomes that are cyclically transmitted by tsetse. Investigations aiming to generate knowledge on the bacterial fauna of tsetse have revealed distinct symbiotic microorganisms. Furthermore, studies addressing the tripartite association between trypanosomes-tsetse-symbionts relationship have so far been contradictory. Most studies included Sodalis glossinudius and, consequently, the association involving Wolbachia is poorly understood. Understanding the vectorial competence of tsetse requires decrypting these tripartite associations. In this study, we identified Wolbachia and trypanosomes in Glossina palpalis palpalis from three human African trypanosomiasis (HAT) foci in southern Cameroon.

METHODS: Tsetse flies were captured with pyramidal traps in the Bipindi, Campo and Fontem HAT foci. After morphological identification, DNA was extracted from whole tsetse flies and Wolbachia and trypanosomes were identified by PCR using different trypanosome-specific primers and two Wolbachia-specific primers (Wolbachia surface protein and 16S rRNA genes). Statistical analyses were performed to compare the trypanosome and Wolbachia infection rates between villages and different foci and to look for an association between these microorganisms.

RESULTS: From a total of 2122 tsetse flies, 790 G. p. palpalis were analyzed. About 25.32% of flies hosted Wolbachia and 31.84% of non-teneral flies were infected by at least one trypanosome species. There was no significant difference between the global Wolbachia prevalence revealed by the two markers while some differences were observed between HAT foci. From 248 G. p. palpalis with trypanosome infections, 62.90% were with T. vivax, 34.68% with T. congolense forest, 16.13% with T. brucei (s.l.) and 2.42% with T. congolense savannah. Of all trypanosome-infected flies, 29.84% hosted Wolbachia and no association was observed between Wolbachia and trypanosome co-infections.

CONCLUSIONS: This study revealed differences in the prevalence of Wolbachia and trypanosomes in G. p. palpalis according to HAT foci. The use of only one marker has underestimated the prevalence of Wolbachia, thus more markers in subsequent studies may improve its detection. The presence of Wolbachia seems to have no impact on the establishment of trypanosomes in G. p. palpalis. The tripartite association between tsetse, Wolbachia and trypanosomes varies according to studied areas. Studies aiming to evaluate the genetic polymorphism of Wolbachia and its density in tsetse flies could help to better understand this association.

RevDate: 2018-12-11

Qi LD, Sun JT, Hong XY, et al (2018)

Diversity and Phylogenetic Analyses Reveal Horizontal Transmission of Endosymbionts Between Whiteflies and Their Parasitoids.

Journal of economic entomology pii:5237751 [Epub ahead of print].

Endosymbionts are widely distributed among insects via intraspecific vertical transmission and interspecific horizontal transmission. Parasitoids have attracted considerable interest due to their possible role in the horizontal transmission of endosymbionts. Horizontal transmission of endosymbionts between whiteflies via parasitoids has been revealed in the laboratory. However, whether this occurs under field conditions remains unknown. Here, the diversity and phylogenetic relationships of endosymbionts in 1,350 whiteflies and 36 parasitoids that emerged from whitefly nymphs collected from three locations in Jiangsu Province of China were investigated. Only Rickettsia and Wolbachia were identified in both whiteflies and parasitoids, with an overall infection frequency of 22.67% in whiteflies and 16.67% in parasitoids for Wolbachia and of 12.15% in whiteflies and 25% in parasitoids for Rickettsia. Despite the distant relationship between whiteflies and their parasitoids, phylogenetic analyses revealed that the Rickettsia and Wolbachia individuals collected from the two types of organisms were grouped together. Furthermore, shared haplotypes were also identified, which was consistent with the horizontal transmission of endosymbionts between parasitoids and whiteflies. In addition, a parasitoid resistance-related symbiont, Hamiltonella, was detected in whiteflies at a 100% infection frequency, probably accounting for the relatively low parasitism of the whiteflies in the field. The factors affecting the infection frequency of the four secondary endosymbionts in whiteflies were also examined.

RevDate: 2018-12-11

Chung M, Munro JB, Tettelin H, et al (2018)

Using Core Genome Alignments To Assign Bacterial Species.

mSystems, 3(6): pii:00236-18.

With the exponential increase in the number of bacterial taxa with genome sequence data, a new standardized method to assign species designations is needed that is consistent with classically obtained taxonomic analyses. This is particularly acute for unculturable, obligate intracellular bacteria with which classically defined methods, like DNA-DNA hybridization, cannot be used, such as those in the Rickettsiales. In this study, we generated nucleotide-based core genome alignments for a wide range of genera with classically defined species, as well as those within the Rickettsiales. We created a workflow that uses the length, sequence identity, and phylogenetic relationships inferred from core genome alignments to assign genus and species designations that recapitulate classically obtained results. Using this method, most classically defined bacterial genera have a core genome alignment that is ≥10% of the average input genome length. Both Anaplasma and Neorickettsia fail to meet this criterion, indicating that the taxonomy of these genera should be reexamined. Consistently, genomes from organisms with the same species epithet have ≥96.8% identity of their core genome alignments. Additionally, these core genome alignments can be used to generate phylogenomic trees to identify monophyletic clades that define species and neighbor-network trees to assess recombination across different taxa. By these criteria, Wolbachia organisms are delineated into species different from the currently used supergroup designations, while Rickettsia organisms are delineated into 9 distinct species, compared to the current 27 species. By using core genome alignments to assign taxonomic designations, we aim to provide a high-resolution, robust method to guide bacterial nomenclature that is aligned with classically obtained results. IMPORTANCE With the increasing availability of genome sequences, we sought to develop and apply a robust, portable, and high-resolution method for the assignment of genera and species designations that can recapitulate classically defined taxonomic designations. Using cutoffs derived from the lengths and sequence identities of core genome alignments along with phylogenetic analyses, we sought to evaluate or reevaluate genus- and species-level designations for diverse taxa, with an emphasis on the order Rickettsiales, where species designations have been applied inconsistently. Our results indicate that the Rickettsia genus has an overabundance of species designations, that the current Anaplasma and Neorickettsia genus designations are both too broad and need to be divided, and that there are clear demarcations of Wolbachia species that do not align precisely with the existing supergroup designations.

RevDate: 2018-12-11

Chung M, Teigen L, Libro S, et al (2018)

Multispecies Transcriptomics Data Set of Brugia malayi, Its Wolbachia Endosymbiont wBm, and Aedes aegypti across the B. malayi Life Cycle.

Microbiology resource announcements, 7(18): pii:MRA01306-18.

Here, we present a comprehensive transcriptomics data set of Brugia malayi, its Wolbachia endosymbiont wBm, and its vector host. This study samples from 16 stages across the entire B. malayi life cycle, including stage 1 through 4 larvae, adult males and females, embryos, immature microfilariae, and mature microfilariae.

RevDate: 2018-12-11

Newton ILG, KB Sheehan (2018)

Gateway Entry Vector Library of Wolbachia pipientis Candidate Effectors from Strain wMel.

Microbiology resource announcements, 7(1): pii:MRA00806-18.

Wolbachia pipientis is an intracellular symbiont that modifies host biology using a type IV secretion system to inject bacterial effectors into the host cytoplasm. We utilized a bioinformatics approach to predict Wolbachia effectors and cloned the candidates into an entry vector, which can be utilized for subsequent analyses.

RevDate: 2018-12-03

McLean BJ, Dainty KR, Flores HA, et al (2018)

Differential suppression of persistent insect specific viruses in trans-infected wMel and wMelPop-CLA Aedes-derived mosquito lines.

Virology, 527:141-145 pii:S0042-6822(18)30359-3 [Epub ahead of print].

Wolbachia suppresses the replication of +ssRNA viruses such as dengue and Zika viruses in Aedes aegypti mosquitoes. However, the range of viruses affected by this endosymbiont is yet to be explored. Recently, novel insect-specific viruses (ISVs) have been described from numerous mosquito species and mosquito-derived cell lines. Cell-fusing agent virus (Flaviviridae) and Phasi Charoen-like virus (Bunyaviridae) persistently infect the Ae. aegypti cell line Aag2 which has been used for experimental studies with both the wMel and wMelPop-CLA strains. Wolbachia was found to restrict the replication of CFAV but not the PCLV infection in these lines. Furthermore, an additional Ae. albopictus cell line (RML-12) which contained either wMel or wMelPop-CLA was assessed. While no infectious +ssRNA or dsRNA viruses were detected, a PCLV infection was identified. These observations provide additional evidence to support that insect-specific, +ssRNA viruses can be suppressed in cell culture by Wolbachia but -ssRNA viruses may not.

RevDate: 2018-12-05

Rahimi-Kaldeh S, Ashouri A, Bandani A, et al (2018)

Abiotic and biotic factors influence diapause induction in sexual and asexual strains of Trichogramma brassicae (Hym: Trichogrammatidae).

Scientific reports, 8(1):17600 pii:10.1038/s41598-018-35626-7.

The effects of some abiotic (maternal photoperiod and offspring developmental temperature) and biotic (host quality during both maternal and offspring generations) factors on diapause induction were investigated for two sympatric strains of Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) differing by infection status with regard to Wolbachia. The mode of reproduction, developmental temperature, maternal photoperiod and the quality of the host significantly affected diapause induction. The highest percentage of diapausing individuals were observed with the sexual strain reared at 14 °C using a "high quality" host and after a long photophase during the maternal generation. Environment-by-Environment, as well as Genotype-by-Environment interactions, was observed. All these patterns were discussed with the goal of providing relevant protocols for the commercial mass-rearing of such biocontrol agents. A successful diapause in beneficial insects could affect the efficiency of mass rearing by increasing the duration of storage conditions based on a high percent emergence and providing a large number of individuals at the appropriate time in the field season.

RevDate: 2018-11-30

Jeffries CL, Tantely LM, Raharimalala FN, et al (2018)

Diverse novel resident Wolbachia strains in Culicine mosquitoes from Madagascar.

Scientific reports, 8(1):17456 pii:10.1038/s41598-018-35658-z.

Wolbachia endosymbiotic bacteria are widespread throughout insect species and Wolbachia transinfected in Aedes mosquito species has formed the basis for biocontrol programs as Wolbachia strains inhibit arboviral replication and can spread through populations. Resident strains in wild Culicine mosquito populations (the vectors of most arboviruses) requires further investigation given resident strains can also affect arboviral transmission. As Madagascar has a large diversity of both Culicine species and has had recent arboviral outbreaks, an entomology survey was undertaken, in five ecologically diverse sites, to determine the Wolbachia prevalence. We detected diverse novel resident Wolbachia strains within the Aedeomyia, Culex, Ficalbia, Mansonia and Uranotaenia genera. Wolbachia prevalence rates and strain characterisation through Sanger sequencing with multilocus sequence typing (MLST) and phylogenetic analysis revealed significant diversity and we detected co-infections with the environmentally acquired bacteria Asaia. Mosquitoes were screened for major arboviruses to investigate if any evidence could be provided for their potential role in transmission and we report the presence of Rift Valley fever virus in three Culex species: Culex tritaeniorhynchus, Culex antennatus and Culex decens. The implications of the presence of resident Wolbachia strains are discussed and how the discovery of novel strains can be utilized for applications in the development of biocontrol strategies.

RevDate: 2018-11-29

Sakamoto H, Suzuki R, Nishizawa N, et al (2018)

Effects of Wolbachia/Cardinium Infection on the Mitochondrial Phylogeny of Oligonychus castaneae (Acari: Tetranychidae).

Journal of economic entomology pii:5212277 [Epub ahead of print].

A wide range of invertebrates harbor intracellular endosymbiotic bacteria. Within these endosymbionts, Wolbachia and Cardinium, have been attracting particular attention because these bacteria frequently affect the genetic structure and genetic diversity of their hosts. They cause various reproductive alterations such as cytoplasmic incompatibility, parthenogenesis induction, male-killing, and feminization. Through these alterations, they also affect the maternally inherited organelles of their hosts. Mitochondrial DNA (mtDNA) can be used for molecular phylogenetic analysis of invertebrates. However, in Wolbachia- or Cardinium-infected invertebrates, phylogenetic trees based on mtDNA are often inconsistent with those based on nuclear DNA. In the present study, we determined the Wolbachia/Cardinium infection status of 45 populations of the mite, Oligonychus castaneae Ehara & Gotoh (Acari: Tetranychidae), collected throughout Japan. Then, we compared phylogenetic trees of O. castaneae based on both the cytochrome c oxidase subunit I (COI) gene of mtDNA and the 28S rRNA gene of nuclear DNA to clarify the effects of Wolbachia and/or Cardinium infection. We found 106 Wolbachia-infected individuals and 250 Cardinium-infected individuals in a total of 450 individuals, indicating an infection rate of 79%. No double-infected individuals were observed. In the 28S tree, almost all populations formed a single group. In the COI tree, O. castaneae formed four separate groups that more closely followed Wolbachia/Cardinium infection than geographic distribution. These results strongly suggest that the endosymbionts affected mitochondrial variation of O. castaneae.

RevDate: 2018-11-28

Jeffries CL, Lawrence GG, Golovko G, et al (2018)

Novel Wolbachia strains in Anopheles malaria vectors from Sub-Saharan Africa.

Wellcome open research, 3:113.

Background:Wolbachia, a common insect endosymbiotic bacterium that can influence pathogen transmission and manipulate host reproduction, has historically been considered absent from the Anopheles (An.) genera, but has recently been found in An. gambiae s.l. populations. As there are numerous Anopheles species that have the capacity to transmit malaria, we analysed a range of species to determine Wolbachia prevalence rates, characterise novel Wolbachia strains and determine any correlation between the presence of Plasmodium, Wolbachia and the competing endosymbiotic bacterium Asaia. Methods:Anopheles adult mosquitoes were collected from five malaria-endemic countries: Guinea, Democratic Republic of the Congo (DRC), Ghana, Uganda and Madagascar, between 2013 and 2017. Molecular analysis of samples was undertaken using quantitative PCR, Sanger sequencing, Wolbachia multilocus sequence typing (MLST) and high-throughput amplicon sequencing of the bacterial 16S rRNA gene. Results: Novel Wolbachia strains were discovered in five species: An. coluzzii, An. gambiae s.s., An. arabiensis, An. moucheti and An. species 'A', increasing the number of Anopheles species known to be naturally infected. Variable prevalence rates in different locations were observed and novel strains were phylogenetically diverse, clustering with Wolbachia supergroup B strains. We also provide evidence for resident strain variants within An. species 'A'. Wolbachia is the dominant member of the microbiome in An. moucheti and An. species 'A', but present at lower densities in An. coluzzii. Interestingly, no evidence of Wolbachia/Asaia co-infections was seen and Asaia infection densities were also shown to be variable and location dependent. Conclusions: The important discovery of novel Wolbachia strains in Anopheles provides greater insight into the prevalence of resident Wolbachia strains in diverse malaria vectors. Novel Wolbachia strains (particularly high-density strains) are ideal candidate strains for transinfection to create stable infections in other Anopheles mosquito species, which could be used for population replacement or suppression control strategies.

RevDate: 2018-11-26

Hosseinzadeh S, Shams-Bakhsh M, Mann M, et al (2018)

Distribution and Variation of Bacterial Endosymbiont and "Candidatus Liberibacter asiaticus" Titer in the Huanglongbing Insect Vector, Diaphorina citri Kuwayama.

Microbial ecology pii:10.1007/s00248-018-1290-1 [Epub ahead of print].

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an economic insect pest in most citrus-growing regions and the vector of 'Candidatus Liberibacter asiaticus' (CLas), one of at least three known bacteria associated with Huanglongbing (HLB or citrus greening disease). D. citri harbors bacterial endosymbionts, including Wolbachia pipientis (strain Wolbachia wDi), 'Candidatus Carsonella ruddii,' and 'Candidatus Profftella armatura.' Many important functions of these bacteria can be inferred from their genome sequences, but their interactions with each other, CLas, and their D. citri host are poorly understood. In the present study, the titers of the endosymbionts in different tissues, in each sex, and in insects reared on healthy citrus (referred to as unexposed) and CLas-infected citrus (referred to as CLas-exposed) D. citri were investigated using real-time, quantitative PCR (qPCR) using two different quantitative approaches. Wolbachia and CLas were detected in all insect tissues. The titer of Wolbachia was higher in heads of CLas-exposed males as compared to unexposed males. In males and females, Wolbachia titer was highest in the Malpighian tubules. The highest titer of CLas was observed in the gut. Profftella and Carsonella titers were significantly reduced in the bacteriome of CLas-exposed males compared with that of unexposed males, but this effect was not observed in females. In ovaries of CLas-exposed females, the Profftella and Carsonella titers were increased as compared to non-exposed females. CLas appeared to influence the overall levels of the symbionts but did not drastically perturb the overall microbial community structure. In all the assessed tissues, CLas titer in males was significantly higher than that of females using absolute quantification. These data provide a better understanding of multi-trophic interactions regulating symbiont dynamics in the HLB pathosystem.

RevDate: 2018-11-27

Doudoumis V, Augustinos A, Saridaki A, et al (2018)

Different laboratory populations similar bacterial profile? The case of Glossina palpalis gambiensis.

BMC microbiology, 18(Suppl 1):148 pii:10.1186/s12866-018-1290-9.

BACKGROUND: Microbiota plays an important role in the biology, ecology and evolution of insects including tsetse flies. The bacterial profile of 3 Glossina palpalis gambiensis laboratory colonies was examined using 16S rRNA gene amplicon sequencing to evaluate the dynamics of the bacterial diversity within and between each G. p. gambiensis colony.

RESULTS: The three G. p. gambiensis laboratory colonies displayed similar bacterial diversity indices and OTU distribution. Larval guts displayed a higher diversity when compared with the gastrointestinal tract of adults while no statistically significant differences were observed between testes and ovaries. Wigglesworthia and Sodalis were the most dominant taxa. In more detail, the gastrointestinal tract of adults was more enriched by Wigglesworthia while Sodalis were prominent in gonads. Interestingly, in larval guts a balanced co-existence between Wigglesworthia and Sodalis was observed. Sequences assigned to Wolbachia, Propionibacterium, and Providencia were also detected but to a much lesser degree. Clustering analysis indicated that the bacterial profile in G. p. gambiensis exhibits tissue tropism, hence distinguishing the gut bacterial profile from that present in reproductive organs.

CONCLUSIONS: Our results indicated that age, gender and the origin of the laboratory colonies did not significantly influence the formation of the bacterial profile, once these populations were kept under the same rearing conditions. Within the laboratory populations a tissue tropism was observed between the gut and gonadal bacterial profile.

RevDate: 2018-11-27

Augustinos AA, Meki IK, Demirbas-Uzel G, et al (2018)

Nuclear and Wolbachia-based multimarker approach for the rapid and accurate identification of tsetse species.

BMC microbiology, 18(Suppl 1):147 pii:10.1186/s12866-018-1295-4.

BACKGROUND: Tsetse flies (Diptera: Glossinidae) are solely responsible for the transmission of African trypanosomes, causative agents of sleeping sickness in humans and nagana in livestock. Due to the lack of efficient vaccines and the emergence of drug resistance, vector control approaches such as the sterile insect technique (SIT), remain the most effective way to control disease. SIT is a species-specific approach and therefore requires accurate identification of natural pest populations at the species level. However, the presence of morphologically similar species (species complexes and sub-species) in tsetse flies challenges the successful implementation of SIT-based population control.

RESULTS: In this study, we evaluate different molecular tools that can be applied for the delimitation of different Glossina species using tsetse samples derived from laboratory colonies, natural populations and museum specimens. The use of mitochondrial markers, nuclear markers (including internal transcribed spacer 1 (ITS1) and different microsatellites), and bacterial symbiotic markers (Wolbachia infection status) in combination with relatively inexpensive techniques such as PCR, agarose gel electrophoresis, and to some extent sequencing provided a rapid, cost effective, and accurate identification of several tsetse species.

CONCLUSIONS: The effectiveness of SIT benefits from the fine resolution of species limits in nature. The present study supports the quick identification of large samples using simple and cost effective universalized protocols, which can be easily applied by countries/laboratories with limited resources and expertise.

RevDate: 2018-11-27

Ouedraogo GMS, Demirbas-Uzel G, Rayaisse JB, et al (2018)

Prevalence of trypanosomes, salivary gland hypertrophy virus and Wolbachia in wild populations of tsetse flies from West Africa.

BMC microbiology, 18(Suppl 1):153 pii:10.1186/s12866-018-1287-4.

BACKGROUND: Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal.

RESULTS: The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected.

CONCLUSION: The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found.

RevDate: 2018-11-27

Kariithi HM, Boucias DG, Murungi EK, et al (2018)

Coevolution of hytrosaviruses and host immune responses.

BMC microbiology, 18(Suppl 1):183 pii:10.1186/s12866-018-1296-3.

BACKGROUND: Hytrosaviruses (SGHVs; Hytrosaviridae family) are double-stranded DNA (dsDNA) viruses that cause salivary gland hypertrophy (SGH) syndrome in flies. Two structurally and functionally distinct SGHVs are recognized; Glossina pallidipes SGHV (GpSGHV) and Musca domestica SGHV (MdSGHV), that infect the hematophagous tsetse fly and the filth-feeding housefly, respectively. Genome sizes and gene contents of GpSGHV (~ 190 kb; 160-174 genes) and MdSGHV (~ 124 kb; 108 genes) may reflect an evolution with the SGHV-hosts resulting in differences in pathobiology. Whereas GpSGHV can switch from asymptomatic to symptomatic infections in response to certain unknown cues, MdSGHV solely infects symptomatically. Overt SGH characterizes the symptomatic infections of SGHVs, but whereas MdSGHV induces both nuclear and cellular hypertrophy (enlarged non-replicative cells), GpSGHV induces cellular hyperplasia (enlarged replicative cells). Compared to GpSGHV's specificity to Glossina species, MdSGHV infects other sympatric muscids. The MdSGHV-induced total shutdown of oogenesis inhibits its vertical transmission, while the GpSGHV's asymptomatic and symptomatic infections promote vertical and horizontal transmission, respectively. This paper reviews the coevolution of the SGHVs and their hosts (housefly and tsetse fly) based on phylogenetic relatedness of immune gene orthologs/paralogs and compares this with other virus-insect models.

RESULTS: Whereas MdSGHV is not vertically transmitted, GpSGHV is both vertically and horizontally transmitted, and the balance between the two transmission modes may significantly influence the pathogenesis of tsetse virus. The presence and absence of bacterial symbionts (Wigglesworthia and Sodalis) in tsetse and Wolbachia in the housefly, respectively, potentially contributes to the development of SGH symptoms. Unlike MdSGHV, GpSGHV contains not only host-derived proteins, but also appears to have evolutionarily recruited cellular genes from ancestral host(s) into its genome, which, although may be nonessential for viral replication, potentially contribute to the evasion of host's immune responses. Whereas MdSGHV has evolved strategies to counteract both the housefly's RNAi and apoptotic responses, the housefly has expanded its repertoire of immune effector, modulator and melanization genes compared to the tsetse fly.

CONCLUSIONS: The ecologies and life-histories of the housefly and tsetse fly may significantly influence coevolution of MdSGHV and GpSGHV with their hosts. Although there are still many unanswered questions regarding the pathogenesis of SGHVs, and the extent to which microbiota influence expression of overt SGH symptoms, SGHVs are attractive 'explorers' to elucidate the immune responses of their hosts, and the transmission modes of other large DNA viruses.

RevDate: 2018-11-27

Schneider DI, Parker AG, Abd-Alla AM, et al (2018)

High-sensitivity detection of cryptic Wolbachia in the African tsetse fly (Glossina spp.).

BMC microbiology, 18(Suppl 1):140 pii:10.1186/s12866-018-1291-8.

BACKGROUND: In African tsetse flies Glossina, spp. detection of bacterial symbionts such as Wolbachia is challenging since their prevalence and distribution are patchy, and natural symbiont titers can range at levels far below detection limit of standard molecular techniques. Reliable estimation of symbiont infection frequency, especially with regard to interrelations between symbionts and their potential impact on host biology, is of pivotal interest in the context of future applications for the control and eradication of Glossina-vectored African trypanosomosis. The presence or absence of symbionts is routinely screened with endpoint polymerase chain reaction (PCR), which has numerous advantages, but reaches its limits, when detecting infections at natural low titer. To not only determine presence of native tsetse symbionts but also to localize them to specific host tissues, fluorescence in situ hybridization (FISH) can be applied. However, classic FISH assays may not detect low-titer infections due to limitations in sensitivity.

RESULTS: We have compared classic endpoint PCR with high-sensitivity blot-PCR. We demonstrate that the latter technique allows for clear detection of low-titer Wolbachia in the morsitans and palpalis groups while classic endpoint PCR does not. In order to localize Wolbachia in situ in high and low-titer Glossina species, we applied high-end Stellaris® rRNA-FISH. We show that with this high sensitivity method, even low amounts of Wolbachia can be traced in specific tissues. Furthermore, we highlight that more tissues and organs than previously recorded are infested with Wolbachia in subspecies of the morsitans and palpalis groups.

CONCLUSIONS: Our results demonstrate that overall symbiont infection frequencies as well as the presence in specific host tissues may be underestimated when using low-sensitivity methods. To better understand the complex interrelation of tsetse flies and their native symbionts plus the pathogenic trypanosomes, it is important to consider application of a broader range of high-sensitivity detection tools.

RevDate: 2018-11-27

Demirbas-Uzel G, De Vooght L, Parker AG, et al (2018)

Combining paratransgenesis with SIT: impact of ionizing radiation on the DNA copy number of Sodalis glossinidius in tsetse flies.

BMC microbiology, 18(Suppl 1):160 pii:10.1186/s12866-018-1283-8.

BACKGROUND: Tsetse flies (Diptera: Glossinidae) are the cyclical vectors of the causative agents of African Trypanosomosis, which has been identified as a neglected tropical disease in both humans and animals in many regions of sub-Saharan Africa. The sterile insect technique (SIT) has shown to be a powerful method to manage tsetse fly populations when used in the frame of an area-wide integrated pest management (AW-IPM) program. To date, the release of sterile males to manage tsetse fly populations has only been implemented in areas to reduce transmission of animal African Trypanosomosis (AAT). The implementation of the SIT in areas with Human African Trypanosomosis (HAT) would require additional measures to eliminate the potential risk associated with the release of sterile males that require blood meals to survive and hence, might contribute to disease transmission. Paratransgenesis offers the potential to develop tsetse flies that are refractory to trypanosome infection by modifying their associated bacteria (Sodalis glossinidius) here after referred to as Sodalis. Here we assessed the feasibility of combining the paratransgenesis approach with SIT by analyzing the impact of ionizing radiation on the copy number of Sodalis and the vectorial capacity of sterilized tsetse males.

RESULTS: Adult Glossina morsitans morsitans that emerged from puparia irradiated on day 22 post larviposition did not show a significant decline in Sodalis copy number as compared with non-irradiated flies. Conversely, the Sodalis copy number was significantly reduced in adults that emerged from puparia irradiated on day 29 post larviposition and in adults irradiated on day 7 post emergence. Moreover, irradiating 22-day old puparia reduced the copy number of Wolbachia and Wigglesworthia in emerged adults as compared with non-irradiated controls, but the radiation treatment had no significant impact on the vectorial competence of the flies.

CONCLUSION: Although the radiation treatment significantly reduced the copy number of some tsetse fly symbionts, the copy number of Sodalis recovered with time in flies irradiated as 22-day old puparia. This recovery offers the opportunity to combine a paratransgenesis approach - using modified Sodalis to produce males refractory to trypanosome infection - with the release of sterile males to minimize the risk of disease transmission, especially in HAT endemic areas. Moreover, irradiation did not increase the vector competence of the flies for trypanosomes.

RevDate: 2018-11-27

Kame-Ngasse GI, Njiokou F, Melachio-Tanekou TT, et al (2018)

Prevalence of symbionts and trypanosome infections in tsetse flies of two villages of the "Faro and Déo" division of the Adamawa region of Cameroon.

BMC microbiology, 18(Suppl 1):159 pii:10.1186/s12866-018-1286-5.

BACKGROUND: Tsetse flies are vectors of human and animal African trypanosomiasis. In spite of many decades of chemotherapy and vector control, the disease has not been eradicated. Other methods like the transformation of tsetse fly symbionts to render the fly refractory to trypanosome infection are being evaluated. The aim of the present study was to evaluate the association between trypanosome infections and the presence of symbionts in these tsetse species. Tsetse flies were trapped in two villages of the "Faro and Déo" Division of the Adamawa region of Cameroon. In the field, tsetse fly species were identified and their infection by trypanosomes was checked by microscopy. In the laboratory, DNA was extracted from their midguts and the presence of symbionts (Sodalis glossinidius and Wolbachia sp.) and trypanosomes was checked by PCR. Symbionts/trypanosomes association tests were performed.

RESULTS: Three tsetse fly species including Glossina tachinoides (90.1%), Glossina morsitans submorsitans (9.4%) and Glossina fuscipes fuscipes (0.5%) were caught. In all the population we obtained an occurrence rate of 37.2% for Sodalis glossinidius and 67.6% for Wolbachia irrespective to tsetse flies species. S. glossinidius and Wolbachia sp. occurrence rates were respectively 37 and 68% for G. tachinoides and 28.6 and 59.5% for G. m. submorsitans. Between Golde Bourle and Mayo Dagoum significant differences were observed in the prevalence of symbionts. Prevalence of trypanosomes were 34.8% for Glossina tachinoides and 40.5% for Glossina morsitans submorsitans. In G. tachinoides, the trypanosome infection rates were 11, 2.6 and 13.7%, respectively, for T. brucei s.l., T. congolense forest type and T. congolense savannah type. In G. m. submorsitans, these infection rates were 16.7, 9.5 and, 2.4% respectively, for T. brucei s.l., T. congolense forest type and T. congolense savannah type.

CONCLUSIONS: The rate of tsetse fly infection by trypanosomes was low compared to those obtained in HAT foci of south Cameroon, and this rate was not statistically linked to the rate of symbiont occurrence. This study allowed to show for the first time the presence of Wolbachia sp. in the tsetse fly sub-species Glossina morsitans submorsitans and Glossina tachinoides.

RevDate: 2018-11-28

Zaidman-Rémy A, Vigneron A, Weiss BL, et al (2018)

What can a weevil teach a fly, and reciprocally? Interaction of host immune systems with endosymbionts in Glossina and Sitophilus.

BMC microbiology, 18(Suppl 1):150 pii:10.1186/s12866-018-1278-5.

The tsetse fly (Glossina genus) is the main vector of African trypanosomes, which are protozoan parasites that cause human and animal African trypanosomiases in Sub-Saharan Africa. In the frame of the IAEA/FAO program 'Enhancing Vector Refractoriness to Trypanosome Infection', in addition to the tsetse, the cereal weevil Sitophilus has been introduced as a comparative system with regards to immune interactions with endosymbionts. The cereal weevil is an agricultural pest that destroys a significant proportion of cereal stocks worldwide. Tsetse flies are associated with three symbiotic bacteria, the multifunctional obligate Wigglesworthia glossinidia, the facultative commensal Sodalis glossinidius and the parasitic Wolbachia. Cereal weevils house an obligatory nutritional symbiosis with the bacterium Sodalis pierantonius, and occasionally Wolbachia. Studying insect host-symbiont interactions is highly relevant both for understanding the evolution of symbiosis and for envisioning novel pest control strategies. In both insects, the long co-evolution between host and endosymbiont has led to a stringent integration of the host-bacteria partnership. These associations were facilitated by the development of specialized host traits, including symbiont-housing cells called bacteriocytes and specific immune features that enable both tolerance and control of the bacteria. In this review, we compare the tsetse and weevil model systems and compile the latest research findings regarding their biological and ecological similarities, how the immune system controls endosymbiont load and location, and how host-symbiont interactions impact developmental features including cuticle synthesis and immune system maturation. We focus mainly on the interactions between the obligate symbionts and their host's immune systems, a central theme in both model systems. Finally, we highlight how parallel studies on cereal weevils and tsetse flies led to mutual discoveries and stimulated research on each model, creating a pivotal example of scientific improvement through comparison between relatively distant models.

RevDate: 2018-11-23

Bi J, Zheng Y, Wang RF, et al (2018)

Wolbachia infection may improve learning and memory capacity of Drosophila by altering host gene expression through microRNA.

Insect biochemistry and molecular biology pii:S0965-1748(18)30294-7 [Epub ahead of print].

Wolbachia are endosymbiotic bacteria present in a wide range of invertebrates. Although their dramatic effects on host reproductive biology have been well studied, little is known about the effects of Wolbachia on the learning and memory capacity (LMC) of hosts, despite their distribution in the host nervous system, including brain. In this study, we found that Wolbachia infection significantly enhanced LMC in both Drosophila melanogaster and D. simulans. Expression of LMC-related genes was significantly increased in the head of D. melanogaster infected with the wMel strain, and among these genes, crebA was up-regulated the most. Knockdown of crebA in Wolbachia-infected flies significantly decreased LMC, while overexpression of crebA in Wolbachia-free flies significantly enhanced the LMC of flies. More importantly, a microRNA (miRNA), dme-miR-92b, was identified to be complementary to the 3'UTR of crebA. Wolbachia infection was correlated with reduced expression of dme-miR-92b in D. melanogaster, and dme-miR-92b negatively regulated crebA through binding to its 3'UTR region. Overexpression of dme-miR-92b in Wolbachia-infected flies by microinjection of agomirs caused a significant decrease in crebA expression and LMC, while inhibition of dme-miR-92b in Wolbachia-free flies by microinjection of antagomirs resulted in a significant increase in crebA expression and LMC. These results suggest that Wolbachia may improve LMC in Drosophila by altering host gene expression through a miRNA-target pathway. Our findings help better understand the host-endosymbiont interactions and, in particular, the impact of Wolbachia on cognitive processes in invertebrate hosts.

RevDate: 2018-11-23

Brown AMV, Wasala SK, Howe DK, et al (2018)

Comparative Genomics of Wolbachia-Cardinium Dual Endosymbiosis in a Plant-Parasitic Nematode.

Frontiers in microbiology, 9:2482.

Wolbachia and Cardinium are among the most important and widespread of all endosymbionts, occurring in nematodes and more than half of insect and arachnid species, sometimes as coinfections. These symbionts are of significant interest as potential biocontrol agents due to their abilities to cause major effects on host biology and reproduction through cytoplasmic incompatibility, sex ratio distortion, or obligate mutualism. The ecological and metabolic effects of coinfections are not well understood. This study examined a Wolbachia-Cardinium coinfection in the plant-parasitic nematode (PPN), Pratylenchus penetrans, producing the first detailed study of such a coinfection using fluorescence in situ hybridization (FISH), polymerase chain reaction (PCR), and comparative genomic analysis. Results from FISH and single-nematode PCR showed 123/127 individuals in a focal population carried Cardinium (denoted strain cPpe), and 48% were coinfected with Wolbachia strain wPpe. Both endosymbionts showed dispersed tissue distribution with highest densities in the anterior intestinal walls and gonads. Phylogenomic analyses confirmed an early place of cPpe and long distance from a sister strain in another PPN, Heterodera glycines, supporting a long history of both Cardinium and Wolbachia in PPNs. The genome of cPpe was 1.36 Mbp with 35.8% GC content, 1,131 predicted genes, 41% having no known function, and missing biotin and lipoate synthetic capacity and a plasmid present in other strains, despite having a slightly larger genome compared to other sequenced Cardinium. The larger genome revealed expansions of gene families likely involved in host-cellular interactions. More than 2% of the genes of cPpe and wPpe were identified as candidate horizontally transferred genes, with some of these from eukaryotes, including nematodes. A model of the possible Wolbachia-Cardinium interaction is proposed with possible complementation in function for pathways such as methionine and fatty acid biosynthesis and biotin transport.

RevDate: 2018-11-21

Singh ND (2018)

Wolbachia Infection Associated with Increased Recombination in Drosophila.

G3 (Bethesda, Md.) pii:g3.118.200827 [Epub ahead of print].

Wolbachia is a maternally-transmitted endosymbiotic bacteria that infects a large diversity of arthropod and nematode hosts. Some strains of Wolbachia are parasitic, manipulating host reproduction to benefit themselves, while other strains of Wolbachia exhibit obligate or facultative mutualisms with their host. The effects of Wolbachia on its host are many, though primarily relate to host immune and reproductive function. Here we test the hypothesis that Wolbachia infection alters the frequency of homologous recombination during meiosis. We use D. melanogaster as a model system, and survey recombination in eight wild-derived Wolbachia-infected (strain wMel) and Wolbachia-uninfected strains, controlling for genotype. We measure recombination in two intervals of the genome. Our results indicate that Wolbachia infection is associated with increased recombination in one genomic interval and not the other. The effect of Wolbachia infection on recombination is thus heterogenous across the genome. Our data also indicate a reproductive benefit of Wolbachia infection; infected females show higher fecundity than their uninfected genotypic controls. Given the prevalence of Wolbachia infection in natural populations, our findings suggest that Wolbachia infection is likely to contribute to recombination rate and fecundity variation among individuals in nature.

RevDate: 2018-11-20

Schneider DI, Ehrman L, Engl T, et al (2018)

Symbiont-Driven Male Mating Success in the Neotropical Drosophila paulistorum Superspecies.

Behavior genetics pii:10.1007/s10519-018-9937-8 [Epub ahead of print].

Microbial symbionts are ubiquitous associates of living organisms but their role in mediating reproductive isolation (RI) remains controversial. We addressed this knowledge gap by employing the Drosophila paulistorum-Wolbachia model system. Semispecies in the D. paulistorum species complex exhibit strong RI between each other and knockdown of obligate mutualistic Wolbachia bacteria in female D. paulistorum flies triggers loss of assortative mating behavior against males carrying incompatible Wolbachia strains. Here we set out to determine whether de novo RI can be introduced by Wolbachia-knockdown in D. paulistorum males. We show that Wolbachia-knockdown D. paulistorum males (i) are rejected as mates by wild type females, (ii) express altered sexual pheromone profiles, and (iii) are devoid of the endosymbiont in pheromone producing cells. Our findings suggest that changes in Wolbachia titer and tissue tropism can induce de novo premating isolation by directly or indirectly modulating sexual behavior of their native D. paulistorum hosts.

RevDate: 2018-11-19

Hamilton PT, Hodson CN, Curtis CI, et al (2018)

Genetics and Genomics of an Unusual Selfish Sex Ratio Distortion in an Insect.

Current biology : CB pii:S0960-9822(18)31364-2 [Epub ahead of print].

Diverse selfish genetic elements have evolved the ability to manipulate reproduction to increase their transmission, and this can result in highly distorted sex ratios [1]. Indeed, one of the major explanations for why sex determination systems are so dynamic is because they are shaped by ongoing coevolutionary arms races between sex-ratio-distorting elements and the rest of the genome [2]. Here, we use genetic crosses and genome analysis to describe an unusual sex ratio distortion with striking consequences on genome organization in a booklouse species, Liposcelis sp. (Insecta: Psocodea), in which two types of females coexist. Distorter females never produce sons but must mate with males (the sons of nondistorting females) to reproduce [3]. Although they are diploid and express the genes inherited from their fathers in somatic tissues, distorter females only ever transmit genes inherited from their mothers. As a result, distorter females have unusual chimeric genomes, with distorter-restricted chromosomes diverging from their nondistorting counterparts and exhibiting features of a giant non-recombining sex chromosome. The distorter-restricted genome has also acquired a gene from the bacterium Wolbachia, a well-known insect reproductive manipulator; we found that this gene has independently colonized the genomes of two other insect species with unusual reproductive systems, suggesting possible roles in sex ratio distortion in this remarkable genetic system.

RevDate: 2018-11-27

Hu L, Huang M, Tang M, et al (2018)

Wolbachia spread dynamics in multi-regimes of environmental conditions.

Journal of theoretical biology, 462:247-258 pii:S0022-5193(18)30562-9 [Epub ahead of print].

Mosquito-borne diseases such as dengue fever and Zika kill more than 700,000 people each year in the world. A novel strategy to control these diseases employs the bacterium Wolbachia whose infection in mosquitoes blocks virus replication. The prerequisite for this measure is to release Wolbachia -infected mosquitoes to replace wild population. Due to the fluctuation of environmental conditions for mosquito growth, we develop and analyze a model of differential equations with parameters randomly changing over multiple environmental regimes. By comparing the dynamics between the stochastic system and constructed auxiliary systems, combined with other techniques, we provide sharp estimates on the threshold releasing level for Wolbachia fixation. We define the alarm period of disease transmission to measure the risk of mosquito-borne diseases. Our numerical simulations suggest that more frequent inter-regime transitions help reduce the alarm period, and the disease transmission is more sensitive to the average climatic conditions than the number of sub-regimes over a given time period. Further numerical examples also indicate that the reduction in the waiting time to suppress 95% of wild population is more evident when the releasing amount is increased up to a double of the wild population.

RevDate: 2018-11-18

Herran B, Cerveau N, Houdelet C, et al (2018)

IGFBP-rP1, a strongly conserved member of the androgenic hormone signalling pathway in Isopoda.

General and comparative endocrinology pii:S0016-6480(18)30278-8 [Epub ahead of print].

The first protein which has been described to interact with the malacostracan Androgenic Gland Hormone (AGH) is a binding protein called IGFBP-rP1. It has been identified and studied in several species of decapods, in which its interaction with the masculinizing hormone and its expression patterns have been established in several ways. However, this protein remains uncharacterised to date in the other malacostracan orders, like Amphipoda and Isopoda, although they were historically the first ones in which the androgenic gland and the corresponding hormone were respectively described. In this article, we identified the IGFBP-rP1 of isopods and established its implication in the pathway of the AGH with a silencing approach in the model species Armadillidium vulgare. We also showed that this gene is expressed in all the tissues of males and females, with a similar pattern in animals infected with Wolbachia, a feminizing endosymbiont of several isopod species. The expression pattern did not differ during the development of uninfected and infected animals either. We finally studied the evolution of the IGFBP-rP1 in 68 isopod species, looking for conserved motifs and evidence of natural selection. Altogether, our results showed that this gene is constitutively expressed and strongly conserved in isopods, in which it likely constitutes a key element of the insulin/IGF signalling pathway. However, we also illustrated that IGFBP-rP1 is not sufficient on its own to explain the different developmental paths taken by the males and the females or feminized genetic males.

RevDate: 2018-11-15

Gomes FM, C Barillas-Mury (2018)

Infection of anopheline mosquitoes with Wolbachia: Implications for malaria control.

PLoS pathogens, 14(11):e1007333 pii:PPATHOGENS-D-18-01140.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
21454 NE 143rd Street
Woodinville, WA 98077

E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )