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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 20 Sep 2018 at 01:43 Created: 

Wolbachia

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: 2018-09-18

Indriani C, Ahmad RA, Wiratama BS, et al (2018)

Baseline Characterization of Dengue Epidemiology in Yogyakarta City, Indonesia, before a Randomized Controlled Trial of Wolbachia for Arboviral Disease Control.

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

Dengue is endemic in Indonesia. Here, we describe the epidemiology of dengue in the city of Yogyakarta, Central Java, as a prelude to implementation of a cluster-randomized trial of Wolbachia for the biocontrol of arboviral transmission. Surveillance records from 2006 to 2016 demonstrate seasonal oscillations of dengue incidence with varying magnitude. Two lines of evidence demonstrate a high force of infection; the hospitalized case burden of patients diagnosed with dengue hemorrhagic fever or dengue shock syndrome over the last decade consisted predominantly of children/adolescents, and a serosurvey of 314 healthy children aged 1-10 years found 68% possessed dengue virus-neutralizing antibodies. Finally, a mobility survey indicated children aged 1-10 years, and particularly 1-5 year-olds, spent most of their daytime hours at home. These findings inform the design of clinical trials to measure the impact of novel vector control methods such as Wolbachia introgression into Aedes aegypti mosquitoes, by providing baseline data on disease incidence and identifying subpopulations for recruitment into prospective studies of dengue virus infection and disease. The mobility survey findings indicate that in cluster trials of interventions applied at the community level, young children can reasonably be expected to spend most of their exposure time, in epidemiological terms, within the treatment arm to which they were randomized.

RevDate: 2018-09-16

Zélé F, Santos JL, Godinho DP, et al (2018)

Wolbachia both aids and hampers the performance of spider mites on different host plants.

FEMS microbiology ecology pii:5097780 [Epub ahead of print].

In the last decades, many studies had revealed the potential role of arthropod bacterial endosymbionts in shaping the host range of generalist herbivores and their performance on different host plants, which, in turn, might affect endosymbiont distribution in herbivores populations. We tested this by measuring the prevalence of endosymbionts in natural populations of the generalist spider mite Tetranychus urticae on different host plants. Focusing on Wolbachia, we then analysed how symbionts affected mite life-history traits on the same host-plants in the laboratory. Overall, the prevalences of Cardinium and Rickettsia were low, whereas that of Wolbachia was high, with the highest values on bean and eggplant and the lowest on morning glory, tomato and zuchini. Although most mite life-history traits were affected by the plant species only, Wolbachia infection was detrimental for egg hatching rate on morning glory and zucchini, and led to a more female-biased sex ratio on morning glory and eggplant. These results suggest that endosymbionts may affect the host range of polyphagous herbivores, both by aiding and hampering their performance, depending on the host plant and on the life-history trait that affects performance the most. Conversely, endosymbiont spread may be facilitated or hindered by the plants on which infected herbivores occur.

RevDate: 2018-09-11

Pascar J, CH Chandler (2018)

A bioinformatics approach to identifying Wolbachia infections in arthropods.

PeerJ, 6:e5486 pii:5486.

Wolbachia is the most widespread endosymbiont, infecting >20% of arthropod species, and capable of drastically manipulating the host's reproductive mechanisms. Conventionally, diagnosis has relied on PCR amplification; however, PCR is not always a reliable diagnostic technique due to primer specificity, strain diversity, degree of infection and/or tissue sampled. Here, we look for evidence of Wolbachia infection across a wide array of arthropod species using a bioinformatic approach to detect the Wolbachia genes ftsZ, wsp, and the groE operon in next-generation sequencing samples available through the NCBI Sequence Read Archive. For samples showing signs of infection, we attempted to assemble entire Wolbachia genomes, and in order to better understand the relationships between hosts and symbionts, phylogenies were constructed using the assembled gene sequences. Out of the 34 species with positively identified infections, eight species of arthropod had not previously been recorded to harbor Wolbachia infection. All putative infections cluster with known representative strains belonging to supergroup A or B, which are known to only infect arthropods. This study presents an efficient bioinformatic approach for post-sequencing diagnosis and analysis of Wolbachia infection in arthropods.

RevDate: 2018-09-10

Liu Y, He B, Li F, et al (2018)

Molecular Identification of Bartonella melophagi and Wolbachia Supergroup F from Sheep Keds in Xinjiang, China.

The Korean journal of parasitology, 56(4):365-370.

To confirm that Bartonella and Wolbachia were carried by sheep keds (Melophagus ovinus) in southern Xinjiang of China, 17 M. ovinus samples, which were collected in Aksu Prefecture, Xinjiang, were randomly selected. In this study, the Bartonella gltA and Wolbachia 16S rRNA gene were amplified through conventional PCR and the sequence of those amplified products, were analyzed. The results demonstrated that Bartonella was carried by all of the 17 sheep keds and Wolbachia was carried by 15 out of them. Bartonella was identified as B. melophagi. Three strains of Wolbachia were supergroup F and 1 strain has not been confirmed yet. It is the first report about Wolbachia supergroup F was found in sheep keds and provided the molecular evidence that B. melophagi and Wolbachia supergroup F were carried by sheep keds in Aksu Prefecture of southern Xinjiang, China. The 2 pathogens were found in sheep keds around Taklimakan Desert for the first time.

RevDate: 2018-09-08

Lopez V, Marie Cortesero A, D Poinsot (2018)

Influence of the symbiont Wolbachia on life history traits of the cabbage root fly (Delia radicum).

Journal of invertebrate pathology pii:S0022-2011(18)30198-8 [Epub ahead of print].

Wolbachia is an endocellular bacteria infecting arthropods and nematodes and is only transmitted vertically by females via the cytoplasm of the egg. It is often a manipulator of host reproduction, causing cytoplasmic incompatibility, thelytokous parthenogenesis, feminization or male killing, which all increase the proportion of infected females in the population. However, Wolbachia can modify life history traits of the host without causing the above phenotypes and each species illustrates the variability of relationships between this remarkably versatile symbiont and its many hosts. We have measured maternal transmission and the impact of a natural Wolbachia infection in the cabbage root fly Delia radicum, a major agricultural pest. We used a population that is polymorphic for the infection to ensure similar genetic and microbiome backgrounds between groups. Maternal transmission of the infection was 100% in our sample. We found no evidence of cytoplasmic incompatibility, thelytokous parthenogenesis, feminization nor male killing. Wolbachia infection significantly reduced hatch rate in infected eggs (by 10%) but improved larvo-nymphal viability sufficiently so that infected eggs nevertheless yielded as many adults as uninfected ones, albeit with a 1.5% longer total development time. Starved and infected ovipositing females suffered significantly reduced viability (20% higher mortality during a 3-day oviposition period) than uninfected females, but mortality was not higher in starved virgin females nor in starved males, suggesting that the energetic cost of the infection is only revealed in extreme conditions. Wolbachia had no effect on egg hatch time or offspring size. The apparently 100% vertical transmission and the significant but mutually compensating effects found suggest that infection might be nearly benign in this host and might only drift slowly, which would explain why the infection rate has been stable in our laboratory (approximately 50% individuals infected) for at least 30 generations.

RevDate: 2018-09-07

Chung M, Teigen L, Liu H, et al (2018)

Targeted enrichment outperforms other enrichment techniques and enables more multi-species RNA-Seq analyses.

Scientific reports, 8(1):13377 pii:10.1038/s41598-018-31420-7.

Enrichment methodologies enable the analysis of minor members in multi-species transcriptomic data. We compared the standard enrichment of bacterial and eukaryotic mRNA to a targeted enrichment using an Agilent SureSelect (AgSS) capture for Brugia malayi, Aspergillus fumigatus, and the Wolbachia endosymbiont of B. malayi (wBm). Without introducing significant systematic bias, the AgSS quantitatively enriched samples, resulting in more reads mapping to the target organism. The AgSS-enriched libraries consistently had a positive linear correlation with their unenriched counterparts (r2 = 0.559-0.867). Up to a 2,242-fold enrichment of RNA from the target organism was obtained following a power law (r2 = 0.90), with the greatest fold enrichment achieved in samples with the largest ratio difference between the major and minor members. While using a single total library for prokaryote and eukaryote enrichment from a single RNA sample could be beneficial for samples where RNA is limiting, we observed a decrease in reads mapping to protein coding genes and an increase in multi-mapping reads to rRNAs in AgSS enrichments from eukaryotic total RNA libraries compared to eukaryotic poly(A)-enriched libraries. Our results support a recommendation of using AgSS targeted enrichment on poly(A)-enriched libraries for eukaryotic captures, and total RNA libraries for prokaryotic captures, to increase the robustness of multi-species transcriptomic studies.

RevDate: 2018-09-07

Leftwich PT, Edgington MP, Harvey-Samuel T, et al (2018)

Recent advances in threshold-dependent gene drives for mosquitoes.

Biochemical Society transactions pii:BST20180076 [Epub ahead of print].

Mosquito-borne diseases, such as malaria, dengue and chikungunya, cause morbidity and mortality around the world. Recent advances in gene drives have produced control methods that could theoretically modify all populations of a disease vector, from a single release, making whole species less able to transmit pathogens. This ability has caused both excitement, at the prospect of global eradication of mosquito-borne diseases, and concern around safeguards. Drive mechanisms that require individuals to be released at high frequency before genes will spread can therefore be desirable as they are potentially localised and reversible. These include underdominance-based strategies and use of the reproductive parasite Wolbachia Here, we review recent advances in practical applications and mathematical analyses of these threshold-dependent gene drives with a focus on implementation in Aedes aegypti, highlighting their mechanisms and the role of fitness costs on introduction frequencies. Drawing on the parallels between these systems offers useful insights into practical, controlled application of localised drives, and allows us to assess the requirements needed for gene drive reversal.

RevDate: 2018-09-03

Jeffries CL, Rogers ME, T Walker (2018)

Establishment of a method for Lutzomyia longipalpis sand fly embryo microinjection: The first step towards potential novel control strategies for leishmaniasis.

Wellcome open research, 3:55.

Leishmaniasis is a vector-borne parasitic disease transmitted by sand flies that affects 1.3 million people across 98 countries, with limited control strategies due to the lack of an available vaccine and the emergence of insecticide resistance. Novel control strategies that are being explored for mosquito-borne diseases, such as Wolbachia bacterial inhibition of pathogens and genetically modified insects (e.g. using CRISPR-Cas9 editing), rely on the ability to consistently inject embryos of the target species. Here we present a novel method to obtain and inject preblastoderm sand fly embryos of the genus Lutzomyia (Lu.)longipalpis, the principle vector of zoonotic visceral leishmaniasis in South America. The procedures required to obtain sufficiently young Lu. longipalpis colony embryos are described alongside a microinjection technique that permits rapid injection and minimal handling of small sand fly embryos post-injection. Using a strain of Wolbachia as a 'marker' for successful injection, our protocol produced early generation Wolbachia transinfected Lu. longipalpis lines, demonstrating its potential as the first step for use in novel applied strategies for sand fly control.

RevDate: 2018-08-30

Cevidanes A, Di Cataldo S, Vera F, et al (2018)

Molecular Detection of Vector-Borne Pathogens in Rural Dogs and Associated Ctenophalides felis Fleas (Siphonaptera: Pulicidae) in Easter Island (Chile).

Journal of medical entomology pii:5079313 [Epub ahead of print].

The presence of vector-borne pathogens of veterinary and public health interest have received little attention in Chile. In Easter Island, in particular, a Chilean territory in the southeastern Pacific Ocean, no information is available. To fill this gap, 153 rural dogs were inspected for ectoparasites during a sterilization campaign carried out in 2016. Fleas were observed in 46% of the dogs, and Ctenophalides felis (Bouché, 1835) was the only species present. Morphological identification of fleas was genetically confirmed using conventional polymerase chain reaction targeting the cox2 gene. No tick was observed in any dog. The presence of DNA of Rickettsia sp. (gltA and ompA fragment genes), Anaplasmataceae (16S rRNA), and Bartonella sp. (16S-23S ribosomal RNA intergenic spacer) was investigated in blood samples of 70 of the dogs and in 126 fleas analyzed in 68 pools that included 1-5 fleas. Rickettsial DNA was detected in 97% (n = 66) of the flea pools. Of these, 57 showed between 99 and 100% identity for both genes with published sequences of Candidatus Rickettsia asemboensis (CRa), six with Rickettsia felis, and one with Candidatus Rickettsia senegalensis. For two pools, gltA amplicons were identical to CRa but ompB amplicions showed 99-100% identity with R. felis. Anaplasmataceae DNA was detected in 16% (n = 11) pools. Sequenced amplicons showed highest identity with the endosymbiont Wolbachia pipientis. Bartonella DNA, showing 99% identity to Bartonella clarridgeiae, was detected in one pool (1.4%). No positive reaction was observed for any dog. This is the first detection of members of the 'R. felis-like' group other than R. felis in Chile.

RevDate: 2018-08-30

Bhadra S, Riedel TE, Saldaña MA, et al (2018)

Direct nucleic acid analysis of mosquitoes for high fidelity species identification and detection of Wolbachia using a cellphone.

PLoS neglected tropical diseases, 12(8):e0006671 pii:PNTD-D-18-00489.

Manipulation of natural mosquito populations using the endosymbiotic bacteria Wolbachia is being investigated as a novel strategy to reduce the burden of mosquito-borne viruses. To evaluate the efficacy of these interventions, it will be critical to determine Wolbachia infection frequencies in Aedes aegypti mosquito populations. However, current diagnostic tools are not well-suited to fit this need. Morphological methods cannot identify Wolbachia, immunoassays often suffer from low sensitivity and poor throughput, while PCR and spectroscopy require complex instruments and technical expertise, which restrict their use to centralized laboratories. To address this unmet need, we have used loop-mediated isothermal amplification (LAMP) and oligonucleotide strand displacement (OSD) probes to create a one-pot sample-to-answer nucleic acid diagnostic platform for vector and symbiont surveillance. LAMP-OSD assays can directly amplify target nucleic acids from macerated mosquitoes without requiring nucleic acid purification and yield specific single endpoint yes/no fluorescence signals that are observable to eye or by cellphone camera. We demonstrate cellphone-imaged LAMP-OSD tests for two targets, the Aedes aegypti cytochrome oxidase I (coi) gene and the Wolbachia surface protein (wsp) gene, and show a limit of detection of 4 and 40 target DNA copies, respectively. In a blinded test of 90 field-caught mosquitoes, the coi LAMP-OSD assay demonstrated 98% specificity and 97% sensitivity in identifying Ae. aegypti mosquitoes even after 3 weeks of storage without desiccant at 37°C. Similarly, the wsp LAMP-OSD assay readily identified the wAlbB Wolbachia strain in field-collected Aedes albopictus mosquitoes without generating any false positive signals. Modest technology requirements, minimal execution steps, simple binary readout, and robust accuracy make the LAMP-OSD-to-cellphone assay platform well suited for field vector surveillance in austere or resource-limited conditions.

RevDate: 2018-08-29

Wenzel MA, Douglas A, SB Piertney (2018)

Microbiome composition within a sympatric species complex of intertidal isopods (Jaera albifrons).

PloS one, 13(8):e0202212 pii:PONE-D-18-05560.

The increasingly recognised effects of microbiomes on the eco-evolutionary dynamics of their hosts are promoting a view of the "hologenome" as an integral host-symbiont evolutionary entity. For example, sex-ratio distorting reproductive parasites such as Wolbachia are well-studied pivotal drivers of invertebrate reproductive processes, and more recent work is highlighting novel effects of microbiome assemblages on host mating behaviour and developmental incompatibilities that underpin or reinforce reproductive isolation processes. However, examining the hologenome and its eco-evolutionary effects in natural populations is challenging because microbiome composition is considerably influenced by environmental factors. Here we illustrate these challenges in a sympatric species complex of intertidal isopods (Jaera albifrons spp.) with pervasive sex-ratio distortion and ecological and behavioural reproductive isolation mechanisms. We deep-sequence the bacterial 16S rRNA gene among males and females collected in spring and summer from two coasts in north-east Scotland, and examine microbiome composition with a particular focus on reproductive parasites. Microbiomes of all species were diverse (overall 3,317 unique sequences among 3.8 million reads) and comprised mainly Proteobacteria and Bacteroidetes taxa typical of the marine intertidal zone, in particular Vibrio spp. However, we found little evidence of the reproductive parasites Wolbachia, Rickettsia, Spiroplasma and Cardinium, suggesting alternative causes of sex-ratio distortion. Notwithstanding, a significant proportion of the variance in microbiome composition among samples was explained by sex (14.1 %), nested within geographic (26.9 %) and seasonal (39.6 %) variance components. The functional relevance of this sex signal was difficult to ascertain given the absence of reproductive parasites, the ephemeral nature of the species assemblages and substantial environmental variability. These results establish the Jaera albifrons species complex as an intriguing system for examining the effects of microbiomes on reproductive processes and speciation, and highlight the difficulties associated with snapshot assays of microbiome composition in dynamic and complex environments.

RevDate: 2018-08-28

Kostaropoulos T, Papageorgiou L, Tsaniras SC, et al (2018)

Carcinogenic Pesticide Control via Hijacking Endosymbiosis; The Paradigm of DSB-A from Wolbachia pipientis for the Management of Otiorhynchus singularis.

In vivo (Athens, Greece), 32(5):1051-1062.

BACKGROUND/AIM: Pesticides have little, if any specificity, to the pathogen they target in most cases. Wide spectrum toxic chemicals are being used to remove pestcides and salvage crops and economies linked to agriculture. The burden on the environment, public health and economy is huge. Traditional pestcide control is based on administering heavy loads of highly toxic compounds and elements that essentially strip all life from the field. Those chemicals are a leading cause of increased cancer related deaths in countryside. Herein, the Trojan horse of endosymbiosis was used, in an effort to control pests using high specificity compounds in reduced quantities.

MATERIALS AND METHODS: Our pipeline has been applied on the case of Otiorhynchus singularis, which is a very widespread pest, whose impact is devastating on a repertoire of crops. To date, there is no specific pesticide nor agent to control it. The deployed strategy involves the inhibition of the key DSB-A enzyme of its endosymbiotic Wolbachia pipientis bacterial strain.

RESULTS: Our methodology, provides the means to design, test and identify highly specific pestcide control substances that minimize the impact of toxic chemicals on health, economy and the environment.

CONCLUSION: All in all, in this study a radical computer-based pipeline is proposed that could be adopted under many other similar scenarios and pave the way for precision agriculture via optimized pest control.

RevDate: 2018-08-28

Brown AMV (2018)

Endosymbionts of Plant-Parasitic Nematodes.

Annual review of phytopathology, 56:225-242.

Some of the most agriculturally important plant-parasitic nematodes (PPNs) harbor endosymbionts. Extensive work in other systems has shown that endosymbionts can have major effects on host virulence and biology. This review highlights the discovery, development, and diversity of PPN endosymbionts, incorporating inferences from genomic data. Cardinium, reported from five PPN hosts to date, is characterized by its presence in the esophageal glands and other tissues, with a discontinuous distribution across populations, and genomic data suggestive of horizontal gene exchange. Xiphinematobacter occurs in at least 27 species of dagger nematode in the ovaries and gut epithelial cells, where genomic data suggest it may serve in nutritional supplementation. Wolbachia, reported in just three PPNs, appears to have an ancient history in the Pratylenchidae and displays broad tissue distribution and genomic features intermediate between parasitic and reproductive groups. Finally, a model is described that integrates these insights to explain patterns of endosymbiont replacement.

RevDate: 2018-08-27

Cerutti F, Modesto P, Rizzo F, et al (2018)

The microbiota of hematophagous ectoparasites collected from migratory birds.

PloS one, 13(8):e0202270 pii:PONE-D-17-39408.

Arthropod vectors are responsible for the transmission of human pathogens worldwide. Several arthropod species are bird ectoparasites, however, no study to date has characterized their microbiota as a whole. We sampled hematophagous ectoparasites that feed on migratory birds and performed 16S rRNA gene metabarcoding to characterize their microbial community. A total of 194 ectoparasites were collected from 115 avian hosts and classified into three groups: a) Hippoboscidae diptera; b) ticks; c) other arthropods. Metabarcoding showed that endosymbionts were the most abundant genera of the microbial community, including Wolbachia for Hippoboscidae diptera, Candidatus Midichloria for ticks, Wolbachia and Arsenophonus for the other arthropod group. Genera including pathogenic species were: Rickettsia, Borrelia, Coxiella, Francisella, Bartonella, Anaplasma. Co-infection with Borrelia-Rickettsia and Anaplasma-Rickettsia was also observed. A global overview of the microbiota of ectoparasites sampled from migratory birds was obtained with the use of 16S rRNA gene metabarcoding. A novel finding is the first identification of Rickettsia in the common swift louse fly, Crataerina pallida. Given their possible interaction with pathogenic viruses and bacteria, the presence of endosymbionts in arthropods merits attention. Finally, molecular characterization of genera, including both pathogenic and symbiont species, plays a pivotal role in the design of targeted molecular diagnostics.

RevDate: 2018-08-24

Richardson KM, Griffin PC, Lee SF, et al (2018)

A Wolbachia infection from Drosophila that causes cytoplasmic incompatibility despite low prevalence and densities in males.

Heredity pii:10.1038/s41437-018-0133-7 [Epub ahead of print].

Wolbachia bacteria are common insect endosymbionts transmitted maternally and capable of spreading through insect populations by cytoplasmic incompatibility (CI) when infected males cause embryo death after mating with uninfected females. Selection in the Wolbachia endosymbiont occurs on female hosts and is expected to favour strong maternal transmission to female offspring, even at the cost of reduced CI. With maternal leakage, nuclear genes are expected to be selected to suppress cytoplasmic incompatibility caused by males while also reducing any deleterious effects associated with the infection. Here we describe a new type of Wolbachia strain from Drosophila pseudotakahashii likely to have arisen from evolutionary processes on host and/or Wolbachia genomes. This strain is often absent from adult male offspring, but always transmitted to females. It leads to males with low or non-detectable Wolbachia that nevertheless show CI. When detected in adult males, the infection has a low density relative to that in females, a phenomenon not previously seen in Wolbachia infections of Drosophila. This Wolbachia strain is common in natural populations, and shows reduced CI when older (infected) males are crossed. These patterns highlight that endosymbionts can have strong sex-specific effects and that high frequency Wolbachia strains persist through effects on female reproduction. Female-limited Wolbachia infections may be of applied interest if the low level of Wolbachia in males reduces deleterious fitness effects on the host.

RevDate: 2018-08-20

Ali H, Muhammad A, Sanda Bala N, et al (2018)

The Endosymbiotic Wolbachia and Host COI Gene Enables to Distinguish Between Two Invasive Palm Pests; Coconut Leaf Beetle, Brontispa longissima and Hispid Leaf Beetle, Octodonta nipae.

Journal of economic entomology pii:5074054 [Epub ahead of print].

To elucidate taxonomic eminence of identical pest species is essential for many ecological and conservation studies. Without proficient skills, accurate molecular identification and characterization are laborious and time-consuming. The coconut leaf beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), is biologically and morphologically identical to hispid leaf beetle, Octodonta nipae (Maulik) (Coleoptera: Chrysomelidae), and is known as the most harming nuisances of palm cultivation worldwide. The present examination was to establish Wolbachia genotyping analysis along with host cytochrome oxidase subunit I (COI) gene for accurate identification between these individuals of the same family (Chrysomelidae). Here, we have cloned and sequenced a gene coding Wolbachia surface protein (wsp) and COI gene regions amplified from both species by polymerase chain reaction. The nucleotide sequences were directly determined (≈600 bp for wsp and ≈804 bp for COI) and aligned using the multiple alignment algorithms in the ESPript3 package and the MEGA5 program. Comparative sequence analysis indicated that the representative of wsp and COI sequences from these two beetles were highly variable. To ensure this bacterial variation, multilocus sequence typing (MLST) of bacterial genes was conducted, and the results vindicated the same trend of variations. Furthermore, the phylogenetic analysis also indicates that B. longissima and O. nipae being the two different species harbors two distinct Wolbachia Hertig and Burt (Rickettsiales: Anaplamataceae) supergroups B and A, respectively. The present outcomes quickly discriminate between these two species. Considering its simplicity and cost-effectiveness, it can be used as a diagnostic tool for discriminating such invasive species particularly B. longissima and O. nipae which has overlapping morphologic characters.

RevDate: 2018-08-16

Showler AJ, TB Nutman (2018)

Imported onchocerciasis in migrants and travelers.

Current opinion in infectious diseases [Epub ahead of print].

PURPOSE OF REVIEW: With increasing international travel and mass global population migration, clinicians in nonendemic countries must be familiar with imported neglected tropical diseases including onchocerciasis, which is commonly known as 'river blindness'.

RECENT FINDINGS: Imported onchocerciasis manifests differently in travelers compared with migrants from endemic areas and is likely underdiagnosed in both groups. Recent clinical studies confirm that eosinophilia is not a sensitive marker for Onchocerca volvulus, with one-third of patients having a normal eosinophil count. Novel diagnostics measuring antibodies to multiple recombinant O. volvulus antigens maintain a high sensitivity while improving specificity compared with conventional pan-filarial serologic testing. A 6-week course of doxycycline has macrofilaricidal activity through Wolbachia depletion and may be useful in nonendemic areas in addition to standard serial ivermectin.

SUMMARY: Recent studies characterizing distinct clinical presentations in travelers and migrants may enable clinicians to better recognize imported onchocerciasis. Although novel diagnostics have improved specificity, most remain restricted to tropical disease reference laboratories and to date there is no marker of cure. Prolonged doxycycline treatment may reduce the need for serial ivermectin, though more potent short-course macrofilaricidal drugs are being developed.

RevDate: 2018-08-15

Russell SL, Lemseffer N, WT Sullivan (2018)

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

PLoS pathogens, 14(8):e1007216 pii:PPATHOGENS-D-18-00975 [Epub ahead of print].

Widespread success of the intracellular bacterium Wolbachia across insects and nematodes is due to efficient vertical transmission and reproductive manipulations. Many strains, including wMel from Drosophila melanogaster, exhibit a specific concentration to the germplasm at the posterior pole of the mature oocyte, thereby ensuring high fidelity of parent-offspring transmission. Transport of Wolbachia to the pole relies on microtubules and the plus-end directed motor kinesin heavy chain (KHC). However, the mechanisms mediating Wolbachia's association with KHC remain unknown. Here we show that reduced levels of the host canonical linker protein KLC results in dramatically increased levels of Wolbachia at the oocyte's posterior, suggesting that KLC and some key associated host cargos outcompete Wolbachia for association with a limited amount of KHC motor proteins. Consistent with this interpretation, over-expression of KHC causes similarly increased levels of posteriorly localized Wolbachia. However, excess KHC has no effect on levels of Vasa, a germplasm component that also requires KHC for posterior localization. Thus, Wolbachia transport is uniquely KHC-limited because these bacteria are likely outcompeted for binding to KHC by some host cargo/linker complexes. These results reveal a novel host-symbiont interaction that underscores the precise regulation required for an intracellular bacterium to co-opt, but not disrupt, vital host processes.

RevDate: 2018-08-14

Flatau R, Segoli M, Khokhlova I, et al (2018)

Wolbachia's role in mediating its flea's reproductive success differs according to flea origin.

FEMS microbiology ecology pii:5068685 [Epub ahead of print].

Endosymbionts-microbes that live within and engage in prolonged and intimate associations with their hosts-are gaining recognition for their direct impact on plant and animal reproduction. Here we used the overlooked Wolbachia-flea system to explore the possibility that endosymbionts may also play a role as mediators in shaping the reproductive success of their hosts. We simultaneously quantified the Wolbachia density in field- and laboratory-originated fleas that fed and mated on rodents for either five or ten days and assessed their body size and current reproductive success. By combining multigroup analysis and model selection approaches, we teased apart the contribution of the direct effects of the flea's physiological age and body size and the mediation effect of its Wolbachia endosymbionts on flea reproductive success, and we showed that the latter was stronger than the former. However, interestingly, the mediation effect was manifested only in laboratory-originated fleas, for which the increase in Wolbachia with age translated into lower reproductive success. These results suggest that some well-supported phenomena, such as aging effects, may be driven by endosymbionts and show once again that the role of endosymbionts in shaping the reproductive success of their host depends on their selective environment.

RevDate: 2018-08-14

Kruse A, Ramsey JS, Johnson R, et al (2018)

'Candidatus Liberibacter asiaticus' minimally alters expression of immunity and metabolism proteins in the hemolymph of Diaphorina citri, the insect vector of Huanglongbing.

Journal of proteome research [Epub ahead of print].

Huanglongbing (HLB), also known as citrus greening disease, is the most serious disease of citrus plants. It is associated with the Gram-negative bacterium 'Candidatus Liberibacter asiaticus' (CLas), which is transmitted between host plants by the hemipteran insect vector Diaphorina citri in a circulative, propagative manner involving specific interactions with various insect tissues, including the hemolymph, fluid that occupies the body cavity akin to insect blood. High resolution quantitative mass spectrometry was performed to investigate the effect of CLas exposure on D. citri hemolymph at the proteome level. In contrast to the broad proteome effects on hundreds of proteins and a diverse array of metabolic pathways previously reported in gut and whole insect proteome analyses, the effect of CLas on the hemolymph was observed to be highly specific, restricted to key immunity and metabolism pathways, and lower in magnitude than that previously observed in the whole insect body and gut. Vitellogenins were abundantly expressed and CLas-responsive. Gene-specific RNA expression analysis suggests that these proteins are expressed in both male and female insects, and may have roles outside of reproductive vitellogenesis. Proteins for fatty acid synthesis were found to be up-regulated, along with metabolic proteins associated with energy production, supported at the organismal level by the previously published observation that D. citri individuals experience a higher level of hunger when reared on CLas-infected plants. Prediction of post-translational modifications identified hemolymph proteins with phosphorylation and acetylation upon CLas exposure. Proteins derived from the three most prominent bacterial endosymbionts of the psyllid were also detected in the hemolymph, and several of these have predicted secretion signals. A DNAK protein, the bacterial HSP70, detected in the hemolymph expressed from Wolbachia pipientis was predicted to encode a eukaryotic nuclear localization signal. Taken together, these data show specific changes to immunity and metabolism in D. citri hemolymph involving host and endosymbiont proteins. These data provide a novel context for proteomic changes seen in other D. citri tissues in response to CLas and align with organismal data on the effects of CLas on D. citri metabolism and reproduction.

RevDate: 2018-08-14

Mukherjee S, Joardar N, Mondal S, et al (2018)

Quinolone-fused cyclic sulfonamide as a novel benign antifilarial agent.

Scientific reports, 8(1):12073 pii:10.1038/s41598-018-30610-7.

Search of potent antifilarial drugs has been a major thrust area in tropical medicine research over the decades. Herein, we report 4,7-dimethyl-3,4,7,8-tetrahydro-3λ6-[1,2]thiazino[4,3-f]quinoline-3,3,8-trione (8l) as a new class of antifilarial agent which is extremely potent, with lethality against all the developmental stages (oocyte, microfilaria and adult) of the filarial parasite Setaria cervi. Molecular investigation on its mode of action revealed that 8l is a typical inducer of reactive oxygen species that triggers oxidative stress inside the filarid and further signals induction of apoptosis by activating both intrinsic and extrinsic pathways. Moreover, 8l is also active against Wolbachia, the essential endosymbiont of several human infectious filarids. Selective toxicity against filarial parasites and non-toxic nature in rat model were found as unique traits of 8l to be a future medicine. Taken en masse, this maiden report on a novel quinolone fused cyclic sulfonamide presents a promising therapeutic lead for lymphatic filariasis in future.

RevDate: 2018-08-09

Jiang W, Zhu J, Wu Y, et al (2018)

Influence of Wolbachia Infection on Mitochondrial DNA Variation in the Genus Polytremis (Lepidoptera: Hesperiidae).

Molecular phylogenetics and evolution pii:S1055-7903(18)30242-2 [Epub ahead of print].

The maternally inherited obligate bacteria Wolbachia is known for infecting the reproductive tissues of a wide range of arthropods and can contribute to phylogenetically discordant patterns between mtDNA and nDNA. In this study, we tested for an association between mito-nuclear discordance in Polytremis and Wolbachia infection. Six of the 17 species of Polytremis were found to be infected with Wolbachia. Overall, 34% (70/204) of Polytremis specimens were Wolbachia positive and three strains of Wolbachia identified using a wsp marker were further characterized as six strains based on MLST markers. Wolbachia acquisition in Polytremis appears to occur mainly through horizontal transmission rather than codivergence based on comparison of the divergence times of Wolbachia and Polytremis species. At the intraspecific level, one of the Wolbachia infections (wNas1) is associated with reduced mtDNA polymorphism in the infected Polytremis population. At the interspecific level, there is one case of mito-nuclear discordance likely caused by introgression of P. fukia mtDNA into P. nascens driven by another Wolbachia strain (wNas3). Based on an absence of infected males, we suspect that one Wolbachia strain (wNas2) affects sex ratio, but the phenotypic effects of the other strains are unclear. These data reveal a dynamic interaction between Polytremis and Wolbachia endosymbionts affecting patterns of mtDNA variation.

RevDate: 2018-08-02

Johnson BJ, Rohde BB, Zeak N, et al (2018)

A low-cost, battery-powered acoustic trap for surveilling male Aedes aegypti during rear-and-release operations.

PloS one, 13(8):e0201709 pii:PONE-D-17-31754.

The Aedes aegypti mosquito is a primary vector of several serious arboviruses throughout the world and is therefore of great concern to many public health organizations. With vector control methodology pivoting towards rearing and releasing large numbers of genetically modified, sterilized, or Wolbachia-infected male mosquitoes to control vector populations, economical surveillance methods for release tracking becomes increasingly necessary. Previous work has identified that male Ae. aegypti are attracted to female wingbeat frequencies and can be captured through artificial playback of these frequencies, but the tested systems are cost-prohibitive for wide-scale monitoring. Thus, we have developed a simple, low-cost, battery-powered, microcontroller-based sound lure which mimics the wingbeat frequency of female Ae. aegypti, thereby attracting males. We then tested the efficacy of this lure in combination with a passive (non-powered) gravid Aedes trap (GAT) against the current gold-standard, the Biogents Sentinel (BGS) trap, which requires main power (household power) and costs several times what the GAT does. Capture rates of male Ae. aegypti in sound-baited GATs (Sound-GATs) in these field tests were comparable to that of the BGS with no inhibitory effects of sound playback on female capture. We conclude that the Sound-GAT is an effective replacement of the costly BGS for surveillance of male Ae. aegypti mosquitoes, particularly in the developing countries where funding is limited, and has the potential to be adapted to target males of other medically important species.

RevDate: 2018-08-02

Fallon AM (2018)

Strain-specific response to ampicillin in Wolbachia-infected mosquito cell lines.

In vitro cellular & developmental biology. Animal pii:10.1007/s11626-018-0279-x [Epub ahead of print].

Wolbachia pipientis (Rickettsiales; Anaplasmataceae) is an obligate intracellular alpha proteobacterium that occurs in arthropods and filarial worms. Some strains of Wolbachia can be maintained as persistent infections in insect cell lines. C/wStr1 cells from the mosquito Aedes albopictus maintain a robust infection with Wolbachia strain wStr, originally isolated from the planthopper, Laodelphax striatellus. To explore possible functions of penicillin-binding proteins expressed from the wStr genome, C/wStr1 cells were exposed to ampicillin. Absolute levels of Wolbachia increased 3.5-fold in ampicillin-treated cells and fivefold in naive cells newly infected with wStr. Because cell numbers were depressed by ampicillin treatment, Wolbachia yield on a per-cell basis increased by 15-fold. The absence of a similar effect on wAlbB in Aa23 host cells suggests that the Wolbachia strain, the presence/absence of genes encoding penicillin-binding proteins, or the interaction between wAlbB and its host cells may modulate the effects of ampicillin.

RevDate: 2018-08-02

Callahan AG, Ross PA, AA Hoffmann (2018)

Small females prefer small males: size assortative mating in Aedes aegypti mosquitoes.

Parasites & vectors, 11(1):445 pii:10.1186/s13071-018-3028-9.

BACKGROUND: With Aedes aegypti mosquitoes now being released in field programmes aimed at disease suppression, there is interest in identifying factors influencing the mating and invasion success of released mosquitoes. One factor that can increase release success is size: released males may benefit competitively from being larger than their field counterparts. However, there could be a risk in releasing only large males if small field females avoid these males and instead prefer small males. Here we investigate this risk by evaluating mating success for mosquitoes differing in size.

RESULTS: We measured mating success indirectly by coupling size with Wolbachia-infected or uninfected mosquitoes and scoring cytoplasmic incompatibility. Large females showed no evidence of a mating preference, whereas small males were relatively more successful than large males when mating with small females, exhibiting an advantage of around 20-25%.

CONCLUSIONS: Because field females typically encompass a wide range of sizes while laboratory reared (and released) males typically fall into a narrow size range of large mosquitoes, these patterns can influence the success of release programmes which rely on cytoplasmic incompatibility to suppress populations and initiate replacement invasions. Releases could include some small males generated under low food or crowded conditions to counter this issue, although this would need to be weighed against issues associated with costs of producing males of various size classes.

RevDate: 2018-08-01

Fukui T, Kiuchi T, Shoji K, et al (2018)

In vivo masculinizing function of the Ostrinia furnacalis Masculinizer gene.

Biochemical and biophysical research communications pii:S0006-291X(18)31612-7 [Epub ahead of print].

The Masculinizer gene (Masc) encodes a CCCH tandem zinc finger protein essential for masculinization and dosage compensation in the silkworm Bombyx mori. Previously we identified a Masc orthologue from the crambid Ostrinia furnacalis (OfMasc) and observed its masculinizing activity in the B. mori cultured cell line BmN-4. However, the role of OfMasc in masculinization of O. furnacalis has not been assessed. In this study, we unexpectedly discovered that all of the male larvae that escaped from Wolbachia-induced embryonic male-killing by OfMasc cRNA injection expressed the female-type splicing variants of O. furnacalis doublesex (Ofdsx). To clarify the role of OfMasc in the masculinization process in vivo, we established a system to monitor both sex chromosome- and dsx splicing-based sexes from a single O. furnacalis embryo. Using this system, we investigated the effects of OfMasc knockdown in early embryos on Ofdsx splicing and found that depletion of OfMasc mRNA in male embryos induced the production of the female-type splicing variants of Ofdsx. This result indicates that OfMasc is required for masculinization in O. furnacalis, and that the Masc protein possesses masculinizing activity in an insect species that is phylogenetically distant from Bombycidae.

RevDate: 2018-07-31

Fisher ML, Watson DW, Osborne JA, et al (2018)

Growth kinetics of endosymbiont Wolbachia in the common bed bug, Cimex lectularius.

Scientific reports, 8(1):11444 pii:10.1038/s41598-018-29682-2.

The common bed bug, Cimex lectularius harbors the endosymbiotic microorganism, Wolbachia (wCle), in a gonad-associated bacteriome as an obligate nutritional mutualist. The obligatory nature of this association suggests that all individuals in C. lectularius populations would be infected with wCle. However, studies spanning the past several decades have reported variation in both infection frequency and relative abundance of wCle in field-collected samples of bed bugs. Since the growth kinetics of wCle is poorly understood, the objective of this study was to quantify wCle over the life cycle of two strains of C. lectularius. Our results highlight that wCle is dynamic during bed bug development, changing relative to life stage, intermolt stage, and blood-fed status. These results suggest new hypotheses about the coordination of Wolbachia growth and regression with its host's physiology and endocrine events. The observed quantitative modulation of wCle during the bed bug life cycle and during periods of starvation may explain the disparities in wCle infections reported in field-collected C. lectularius.

RevDate: 2018-07-30

Gillespie JJ, Driscoll TP, Verhoeve VI, et al (2018)

A tangled web: origins of reproductive parasitism.

Genome biology and evolution pii:5060530 [Epub ahead of print].

While typically a flea parasite and opportunistic human pathogen, the presence of Rickettsia felis (strain LSU-Lb) in the non-blood-feeding, parthenogenetically-reproducing booklouse, Liposcelis bostrychophila, provides a system to ascertain factors governing not only host transitions but also obligate reproductive parasitism (RP). Analysis of plasmid pLbAR, unique to . felis str. LSU-Lb, revealed a toxin-antitoxin module with similar features to prophage-encoded toxin-antitoxin modules utilized by parasitic Wolbachia strains to induce another form of RP, cytoplasmic incompatibility, in their arthropod hosts. Curiously, multiple deubiquitinase and nuclease domains of the large (3841 aa) pLbAR toxin, as well the entire antitoxin, facilitated the detection of an assortment of related proteins from diverse intracellular bacteria, including other reproductive parasites. Our description of these remarkable components of the intracellular mobilome, including their presence in certain arthropod genomes, lends insight on the evolution of RP, while invigorating research on parasite-mediated biocontrol of arthropod-borne viral and bacterial pathogens.

RevDate: 2018-07-30

Xue L, Fang X, JM Hyman (2018)

Comparing the effectiveness of different strains of Wolbachia for controlling chikungunya, dengue fever, and zika.

PLoS neglected tropical diseases, 12(7):e0006666 pii:PNTD-D-17-01575 [Epub ahead of print].

Once Aedes aegypti and Aedes albopictus mosquitoes that spread Chikungunya virus, dengue virus, and Zika virus are infected with Wolbachia, they have reduced egg laying rates, reduced transmission abilities, and shorter lifespans. Since most infected mosquitoes are only infectious in the last few days of their lives, shortening a mosquito's lifespan by a day or two can greatly reduce their abilities to spread mosquito-borne viral diseases, such as Chikungunya, dengue fever, and Zika. We developed a mathematical model to compare the effectiveness of the wMel and wAlbB strains of Wolbachia for controlling the spread of these viruses. The differences among the diseases, mosquitoes, and Wolbachia strains are captured by the model parameters for the mosquito-human transmission cycle. Moreover, the model accounts for the behavior changes of infectious population created by differences in the malaise caused by these viruses. We derived the effective and basic reproduction numbers for the model that are used to estimate the number of secondary infections from the infectious populations. In the same density of Wolbachia-free Aedes aegypti or Aedes albopictus mosquitoes, we observed that wMel and wAlbB strains of Wolbachia can reduce the transmission rates of these diseases effectively.

RevDate: 2018-07-29

Ciuca L, Simon F, Rinaldi L, et al (2018)

Seroepidemiological survey of human exposure to Dirofilaria spp. in Romania and Moldova.

Acta tropica pii:S0001-706X(17)31455-9 [Epub ahead of print].

The present study aimed to evaluate the extent of Dirofilaria immitis and D. repens exposure in humans from eastern and southern areas of Romania and central Moldova by serological methods. The serological screening was performed on a total of 450 serum samples (187 from Romania and 263 from Moldova). The sera were collected using a convenience sampling with the help of physicians from the hospitals of the study areas. All samples were analysed by a non-commercial ELISA test for the detection of IgG antibodies against adult somatic antigens of D. immitis and D. repens. The results showed a total of 49 (10.9%; 95% CI = 8.3-14.1%) individuals from Romania and Moldova with a positive response to IgG antibodies against both adult somatic antigens of D. immitis and D. repens. Specifically, 48 (10.7%; 95% CI = 8.0-14.0%) patients were positive for IgG-antibodies against adult somatic antigens of D. immitis, one (0.2%; 95% CI = 0.4-1.2%) against D. repens antigens, and four (0.9%; 95% CI = 0.4-3.3%). were positive for antigens of both parasites. At country level, out of 187 samples from Romania, 13 (6.9%; 95% CI = 4.1-11.5%) were positive for anti-D. immitis IgG with high exposure in the southern part of the country (Bucharest). Of the 263 people from Moldova, 36 (13.7%; 95% CI = 10.0-18.4%) were positive for D. immitis antigens from which three (1.1%, 95% CI = 0.4-3.3%) were positive for the antibodies against antigens of both parasites. Only one sample was found positive for anti-D. repens IgG. Positive IgG-ELISA results were confirmed by Western blot analysis. In addition, for further confirmation, a complementary ELISA was performed for anti-WSP IgG antibodies against Wolbachia endosymbionts. Our findings showed a noticeable exposure of humans from Romania and Moldova to Dirofilaria parasites. Serology can be useful for indicating exposure to Dirofilaria spp. in a healthy population in order to obtain useful data on the epidemiological scenario of human dirofilariosis in Eastern Europe.

RevDate: 2018-07-27

Shi M, White VL, Schlub T, et al (2018)

No detectable effect of Wolbachia wMel on the prevalence and abundance of the RNA virome of Drosophila melanogaster.

Proceedings. Biological sciences, 285(1883): pii:rspb.2018.1165.

Wolbachia is an endosymbiotic bacterium that can block viral infections in arthropods, generating interest in its potential to control the spread of mosquito-borne disease. Drosophila melanogaster is model organism for Wolbachia infection, and the wMel strain of Wolbachia can improve host survival following viral infection. However, it is unclear whether wMel induces anti-viral blocking against the broader native virome of D. melanogaster, or whether the major effect of Wolbachia is a reduction in viral abundance rather than viral clearance. We examined the effect of Wolbachia on viral abundance by comparing the total transcriptome of wMel-positive and wMel-negative D. melanogaster populations sampled from six locations in Australia. In addition, we examined the impact of wMel on individual flies by obtaining transcriptome data from 20 wMel-positive and 20 wMel-negative D. melanogaster from the location (Melbourne) with highest density of wMel. These data revealed high viral abundance in both Wolbachia-positive and -negative populations and individuals. Notably, none of the viral species identified, representing RNA viruses from at least nine families/floating genera, showed evidence of protection by wMel. Although the viral loads of picorna-like viruses are reduced by wMel under experimental conditions, we observed no such effect here. These data show that D. melanogaster can harbour abundant RNA viruses regardless of its Wolbachia status and imply that the interaction between Wolbachia and viruses in nature is more complex than simple blocking.

RevDate: 2018-07-27

Ta-Tang TH, Crainey JL, Post RJ, et al (2018)

Mansonellosis: current perspectives.

Research and reports in tropical medicine, 9:9-24 pii:rrtm-9-009.

Mansonellosis is a filarial disease caused by three species of filarial (nematode) parasites (Mansonella perstans, Mansonella streptocerca, and Mansonella ozzardi) that use humans as their main definitive hosts. These parasites are transmitted from person to person by bloodsucking females from two families of flies (Diptera). Biting midges (Ceratopogonidae) transmit all three species of Mansonella, but blackflies (Simuliidae) are also known to play a role in the transmission of M. ozzardi in parts of Latin America. M. perstans and M. streptocerca are endemic in western, eastern, and central Africa, and M. perstans is also present in the neotropical region from equatorial Brazil to the Caribbean coast. M. ozzardi has a patchy distribution in Latin America and the Caribbean. Mansonellosis infections are thought to have little pathogenicity and to be almost always asymptomatic, but occasionally causing itching, joint pains, enlarged lymph glands, and vague abdominal symptoms. In Brazil, M. ozzardi infections are also associated with corneal lesions. Diagnosis is usually performed by detecting microfilariae in peripheral blood or skin without any periodicity. There is no standard treatment at present for mansonellosis. The combination therapy of diethylcarbamazine plus mebendazole for M. perstans microfilaremia is presently one of the most widely used, but the use of ivermectin has also been proven to be very effective against microfilariae. Recently, doxycycline has shown excellent efficacy and safety when used as an antimicrobial against endosymbiotic Wolbachia bacteria harbored by some strains of M. perstans and M. ozzardi. Diethylcarbamazine and ivermectin have been used effectively to treat M. streptocerca infection. There are at present no estimates of the disease burden caused by mansonellosis, and thus its importance to many global health professionals and policy makers is presently limited to how it can interfere with diagnostic tools used in modern filarial disease control and elimination programs aimed at other species of filariae.

RevDate: 2018-07-22

Ahmadi S, N Poorjavad (2018)

Behavioral and Biological Effects of Exposure to Tuta absoluta (Lepidoptera: Gelechiidae) Sex Pheromone on Several Trichogramma (Hymenoptera: Trichogrammatidae) Populations.

Journal of economic entomology pii:5055929 [Epub ahead of print].

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of tomato worldwide. Biological control of the pest using Trichogramma (Hymenoptera: Trichogrammatidae) wasps can be combined with other practices such as use of synthetic sex pheromones for mating disruption or mass trapping programs. In this study, effects of T. absoluta sex pheromone on behavioral responses and fertility life table parameters of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae), Wolbachia-uninfected (W-) Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae), and Wolbachia-infected (W+) T. brassicae were investigated under laboratory conditions. Female wasps of T. evanescens and T. brassicae (W+) were attracted to the pest synthetic sex pheromone (around 62%) and calling virgin female moths (around 75%) and their responses were affected by the wasp age and temperature. Exposure to the host synthetic sex pheromone significantly reduced the percentage of adult emergence, longevity, and fecundity of female wasps, as well as the time spent to find a mate and duration of mating. However, tested populations were not affected similarly. Despite the laboratory tests, greenhouse experiments showed that the wasps were not caught in the traps baited with T. absoluta synthetic sex pheromone. Complementary studies are needed to precisely determine possible interference between pheromone application and releasing Trichogramma Westwood (Hymenoptera: Trichogrammatidae) wasps to achieve a successful integrated control of T. absoluta.

RevDate: 2018-07-20

Zheng B, J Yu (2018)

Characterization of Wolbachia enhancing domain in mosquitoes with imperfect maternal transmission.

Journal of biological dynamics, 12(1):596-610.

A novel method to reduce the burden of dengue is to seed wild mosquitoes with Wolbachia-infected mosquitoes in dengue-endemic areas. Concerns in current mathematical models are to locate the Wolbachia introduction threshold. Our recent findings manifest that the threshold is highly dependent on the initial population size once Wolbachia infection alters the logistic control death rate of infected females. However, counting mosquitoes is beyond the realms of possibility. A plausible method is to monitor the infection frequency. We propose the concept of Wolbachia enhancing domain in which the infection frequency keeps increasing. A detailed description of the domain is presented. Our results suggest that both the initial population size and the infection frequency should be taken into account for optimal release strategies. Both Wolbachia fixation and extinction permit the oscillation of the infection frequency.

RevDate: 2018-07-18

PLOS ONE Staff (2018)

Correction: First detection of Wolbachia in the New Zealand biota.

PloS one, 13(7):e0201151 pii:PONE-D-18-20597.

[This corrects the article DOI: 10.1371/journal.pone.0195517.].

RevDate: 2018-07-18

Moretti R, Yen PS, Houé V, et al (2018)

Combining Wolbachia-induced sterility and virus protection to fight Aedes albopictus-borne viruses.

PLoS neglected tropical diseases, 12(7):e0006626 pii:PNTD-D-18-00260 [Epub ahead of print].

Among the strategies targeting vector control, the exploitation of the endosymbiont Wolbachia to produce sterile males and/or invasive females with reduced vector competence seems to be promising. A new Aedes albopictus transinfection (ARwP-M) was generated by introducing wMel Wolbachia in the ARwP line which had been established previously by replacing wAlbA and wAlbB Wolbachia with the wPip strain. Various infection and fitness parameters were studied by comparing ARwP-M, ARwP and wild-type (SANG population) Ae. albopictus sharing the same genetic background. Moreover, the vector competence of ARwP-M related to chikungunya, dengue and zika viruses was evaluated in comparison with ARwP. ARwP-M showed a 100% rate of maternal inheritance of wMel and wPip Wolbachia. Survival, female fecundity and egg fertility did not show to differ between the three Ae. albopictus lines. Crosses between ARwP-M males and SANG females were fully unfertile regardless of male age while egg hatch in reverse crosses increased from 0 to about 17% with SANG males aging from 3 to 17 days. When competing with SANG males for SANG females, ARwP-M males induced a level of sterility significantly higher than that expected for an equal mating competitiveness (mean Fried index of 1.71 instead of 1). The overall Wolbachia density in ARwP-M females was about 15 fold higher than in ARwP, mostly due to the wMel infection. This feature corresponded to a strongly reduced vector competence for chikungunya and dengue viruses (in both cases, 5 and 0% rates of transmission at 14 and 21 days post infection) with respect to ARwP females. Results regarding Zika virus did not highlight significant differences between ARwP-M and ARwP. However, none of the tested ARwP-M females was capable at transmitting ZIKV. These findings are expected to promote the exploitation of Wolbachia to suppress the wild-type Ae. albopictus populations.

RevDate: 2018-07-17

Karatepe B, Aksoy S, M Karatepe (2018)

Investigation of Wolbachia spp. and Spiroplasma spp. in Phlebotomus species by molecular methods.

Scientific reports, 8(1):10616 pii:10.1038/s41598-018-29031-3.

The aim of this study was to determine the presence of Wolbachia spp. and Spiroplasma spp. in natural populations of sand flies in Turkey by molecular methods. A total of 40 Phlebotomus specimens (19 female and 21 male) were used in this study. Genomic DNA from whole sand flies was isolated and Wolbachia spp. infection prevalence was investigated by using Wolbachia gene specific primer sets (wsp and GroEL). In addition, the DNA were analyzed for the presence of Spiroplasma infections utilizing bacterium specific 16 S rDNA PCR-amplification primers. Results of this analysis showed a Wolbachia infection prevalence of 70% (28/40). There was no sex-bias in infection prevalence, being 76% (16/21) and 63% (12/19) in males and females, respectively. Analysis of Spiroplasma infections indicated that 26% (5/19) of female sand flies were positive for infection, while none of the screened males (0/21) were positive. Of the 40 sand fly samples, only 2 were found to be positive for both Wolbachia spp. and Spiroplasma spp. The present study demonstrates the presence of Wolbachia and Spiroplasma infections in the natural sand fly populations in Turkey. This is the first report on Spiroplasma infection in the sand flies from Turkey.

RevDate: 2018-07-10

Guo Y, Hoffmann AA, Xu XQ, et al (2018)

Wolbachia-induced Apoptosis Associated with Increased Fecundity in Laodelphax striatellus (Hemiptera: Delphacidae).

Insect molecular biology [Epub ahead of print].

Wolbachia influence the fitness of their invertebrate hosts. They have effects on reproductive incompatibility and egg production. Although the former are well characterized, the mechanistic basis of the latter is unclear. Here, we investigate whether apoptosis, which has been implicated in fecundity in model insects, influences the interaction between fecundity and Wolbachia in the planthopper, Laodelphax striatellus. Wolbachia-infected females produced about 30% more eggs than uninfected females. We used TUNEL staining to visualize apoptosis. Microscopic observations indicated that the Wolbachia strain wStri increased the number of ovarioles that contained apoptotic nurse cells in both young and aged adult females. The frequency of apoptosis was much higher in the infected females. The increased fecundity appeared to be due to apoptosis of nurse cells, which provides nutrients to the growing oocytes. In addition, cell apoptosis inhibition by caspase mRNA interference (RNAi) in Wolbachia infected L. striatellus markedly decreased egg numbers. Together, these data suggest that wStri might enhance fecundity by increasing the number of apoptotic cells in the ovaries in a caspase-dependent manner. Our findings establish a link between Wolbachia-induced apoptosis and egg production effects mediated by Wolbachia, although the way that the endosymbiont influences caspase levels remains to be determined. This article is protected by copyright. All rights reserved.

RevDate: 2018-07-20

Ali H, Muhammad A, Bala NS, et al (2018)

Genomic evaluations of Wolbachia and mtDNA in the population of coconut hispine beetle, Brontispa longissima (Coleoptera: Chrysomelidae).

Molecular phylogenetics and evolution pii:S1055-7903(18)30254-9 [Epub ahead of print].

Wolbachia pipientis is a diverse, ubiquitous and most prevalent intracellular bacterial group of alpha-Proteobacteria that is concerned with many biological processes in arthropods. The coconut hispine beetle (CHB), Brontispa longissima (Gestro) is an economically important pest of palm cultivation worldwide. In the present study, we comprehensively surveyed the Wolbachia-infection prevalence and mitochondrial DNA (mtDNA) polymorphism in CHB from five different geographical locations, including China's Mainland and Taiwan, Vietnam, Thailand, Malaysia and Indonesia. A total of 540 sequences were screened in this study through three different genes, i.e., cytochrome oxidase subunit I (COI), Wolbachia outer surface protein (wsp) and multilocus sequencing type (MLST) genes. The COI genetic divergence ranges from 0.08% to 0.67%, and likewise, a significant genetic diversity (π = 0.00082; P = 0.049) was noted within and between all analyzed samples. In the meantime, ten different haplotypes (H) were characterized (haplotype diversity = 0.4379) from 21 different locations, and among them, H6 (46 individuals) have shown a maximum number of population clusters than others. Subsequently, Wolbachia-prevalence results indicated that all tested specimens of CHB were found positive (100%), which suggested that CHB was naturally infected with Wolbachia. Wolbachia sequence results (wsp gene) revealed a high level of nucleotide diversity (π = 0.00047) under Tajima's D test (P = 0.049). Meanwhile, the same trend of nucleotide diversity (π = 0.00041) was observed in Wolbachia concatenated MLST locus. Furthermore, phylogenetic analysis (wsp and concatenated MLST genes) revealed that all collected samples of CHB attributed to same Wolbachia B-supergroup. Our results strongly suggest that Wolbachia bacteria and mtDNA were highly concordant with each other and Wolbachia can affect the genetic structure and diversity within the CHB populations.

RevDate: 2018-07-04

Truitt AM, Kapun M, Kaur R, et al (2018)

Wolbachia modifies thermal preference in Drosophila melanogaster.

Environmental microbiology [Epub ahead of print].

Environmental variation can have profound and direct effects on fitness, fecundity, and host-symbiont interactions. Replication rates of microbes within arthropod hosts, for example, are correlated with incubation temperature but less is known about the influence of host-symbiont dynamics on environmental preference. Hence, we conducted thermal preference (Tp) assays and tested if infection status and genetic variation in endosymbiont bacterium Wolbachia affected temperature choice of Drosophila melanogaster. We demonstrate that isogenic flies infected with Wolbachia preferred lower temperatures compared to uninfected Drosophila. Moreover, Tp varied with respect to three investigated Wolbachia variants (wMel, wMelCS and wMelPop). While uninfected individuals preferred 24.4°C, we found significant shifts of -1.2°C in wMel- and -4°C in flies infected either with wMelCS or wMelPop. We, therefore, postulate that Wolbachia-associated Tp variation within a host species might represent a behavioral accommodation to host-symbiont interactions and trigger behavioral self-medication and bacterial titer regulation by the host. This article is protected by copyright. All rights reserved.

RevDate: 2018-07-03

Yeap HL, Endersby-Harshman NM, AA Hoffmann (2018)

The Effect of Nonrandom Mating on Wolbachia Dynamics: Implications for Population Replacement and Sterile Releases in Aedes Mosquitoes.

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

Wolbachia bacteria are known to cause deviations from random mating and affect sperm competition (SC) in some of their arthropod hosts. Because these effects could influence the effectiveness of Wolbachia in mosquito population replacement and suppression programs, we developed a theoretical framework to investigate them and we collected relevant data for the wMel infection in Aedes aegypti. Using incompatibility patterns as a measure of mating success of infected versus uninfected mosquitoes, we found some evidence that uninfected males sire more offspring than infected males. However, our theoretical framework suggests that this effect is unlikely to hamper Wolbachia invasion and has only minor effects on population suppression programs. Nevertheless, we suggest that mating effects and SC need to be monitored in an ongoing manner in release programs, given the possibility of ongoing selection for altered mating patterns.

RevDate: 2018-07-03

Nesvorna M, Bittner V, J Hubert (2018)

The Mite Tyrophagus putrescentiae Hosts Population-Specific Microbiomes That Respond Weakly to Starvation.

Microbial ecology pii:10.1007/s00248-018-1224-y [Epub ahead of print].

The effect of short-term nutrient deprivation was studied in five populations of the mite Tyrophagus putrescentiae with different microbiomes. The fresh weight, nutrient status, respiration, and population growth of the mites were observed for the five mite population-scale samples. The starvation caused the larvae and nymphs to be eliminated, resulting in a significant increase in the fresh weight of starved adult specimens. Three populations were negatively influenced by starvation, and the starved specimens were characterized by a decrease in nutrient status, respiration, and population growth. One population was not influenced or was slightly influenced by starvation, which had no effect on population growth or nutrient contents but caused a significant decrease in respiration. One population was positively influenced by starvation; the population growth increased in starved specimens, and starvation had no effect on respiration. Although starvation altered the bacterial profiles of the microbiomes, these differences were much smaller than those between the populations. The bacterial profiles of Staphylococcus, Bacillus, Kocuria, Brevibacterium, and unidentified Micrococcaceae and Enterobacteriaceae increased in starved specimens, whereas those of Bartonella and Solitalea-like genera were reduced in the starved mite populations. The profiles of the intracellular symbiont Cardinium decreased in the starved specimens, and the Wolbachia profile changes were dependent on the mite population. In mite populations, when the symbionts were rare, their profiles varied stochastically. Correlations between changes in the profiles of the bacterial taxa and mite fitness parameters, including nutrient status (lipids, proteins, saccharides, and glycogen contents), mite population growth, and respiration, were observed. Although the microbiomes were resistant to the perturbations caused by nutrition deficiency, the responses of the mites differed in terms of their population growth, respiration, and nutrient status.

RevDate: 2018-07-03

Ross PA, AA Hoffmann (2018)

Continued Susceptibility of the wMel Wolbachia Infection in Aedes aegypti to Heat Stress Following Field Deployment and Selection.

Insects, 9(3): pii:insects9030078.

Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia are being deployed to control the spread of arboviruses around the world through blockage of viral transmission. Blockage by Wolbachia in some scenarios may be affected by the susceptibility of wMel to cyclical heat stress during mosquito larval development. We therefore evaluated the potential to generate a heat-resistant strain of wMel in Ae. aegypti through artificial laboratory selection and through exposure to field temperatures across multiple generations. To generate an artificially selected strain, wMel-infected females reared under cyclical heat stress were crossed to wMel-infected males reared at 26 °C. The low proportion of larvae that hatched founded the next generation, and this process was repeated for eight generations. The wMel heat-selected strain (wMel-HS) was similar to wMel (unselected) in its ability to induce cytoplasmic incompatibility and restore compatibility when larvae were reared under cyclical heat stress, but wMel-HS adults exhibited reduced Wolbachia densities at 26 °C. To investigate the effects of field exposure, we compared the response of wMel-infected Ae. aegypti collected from Cairns, Australia where the infection has been established for seven years, to a wMel-infected population maintained in the laboratory for approximately 60 generations. Field and laboratory strains of wMel did not differ in their response to cyclical heat stress or in their phenotypic effects at 26 °C. The capacity for the wMel infection in Ae. aegypti to adapt to high temperatures therefore appears limited, and alternative strains may need to be considered for deployment in environments where high temperatures are regularly experienced in mosquito breeding sites.

RevDate: 2018-07-13

Ballesteros C, Geary JF, Mackenzie CD, et al (2018)

Characterization of Divalent Metal Transporter 1 (DMT1) in Brugia malayi suggests an intestinal-associated pathway for iron absorption.

International journal for parasitology. Drugs and drug resistance, 8(2):341-349.

Lymphatic filariasis and onchocerciasis are neglected parasitic diseases which pose a threat to public health in tropical and sub-tropical regions. Strategies for control and elimination of these diseases by mass drug administration (MDA) campaigns are designed to reduce symptoms of onchocerciasis and transmission of both parasites to eventually eliminate the burden on public health. Drugs used for MDA are predominantly microfilaricidal, and prolonged rounds of treatment are required for eradication. Understanding parasite biology is crucial to unravelling the complex processes involved in host-parasite interactions, disease transmission, parasite immune evasion, and the emergence of drug resistance. In nematode biology, large gaps still exist in our understanding of iron metabolism, iron-dependent processes and their regulation. The acquisition of iron from the host is a crucial determinant of the success of a parasitic infection. Here we identify a filarial ortholog of Divalent Metal Transporter 1 (DMT1), a member of a highly conserved family of NRAMP proteins that play an essential role in the transport of ferrous iron in many species. We cloned and expressed the B. malayi NRAMP ortholog in the iron-deficient fet3fet4 strain of Saccharomyces cerevisiae, performed qPCR to estimate stage-specific expression, and localized expression of this gene by immunohistochemistry. Results from functional iron uptake assays showed that expression of this gene in the iron transport-deficient yeast strain significantly rescued growth in low-iron medium. DMT1 was highly expressed in adult female and male B. malayi and Onchocerca volvulus. Immunolocalization revealed that DMT1 is expressed in the intestinal brush border, lateral chords, and reproductive tissues of males and females, areas also inhabited by Wolbachia. We hypothesize based on our results that DMT1 in B. malayi functions as an iron transporter. The presence of this transporter in the intestine supports the hypothesis that iron acquisition by adult females requires oral ingestion and suggests that the intestine plays a functional role in at least some aspects of nutrient uptake.

RevDate: 2018-06-28

Parry R, S Asgari (2018)

Aedes anphevirus (AeAV): an insect-specific virus distributed worldwide in Aedes aegypti mosquitoes that has complex interplays with Wolbachia and dengue virus infection in cells.

Journal of virology pii:JVI.00224-18 [Epub ahead of print].

Insect specific viruses (ISVs) of the yellow fever mosquito Aedes aegypti have been demonstrated to modulate transmission of arboviruses such as dengue virus (DENV) and West Nile virus by the mosquito. The diversity and composition of the virome of Ae. aegypti, however, remains poorly understood. In this study, we characterised Aedes anphevirus (AeAV), a negative-sense RNA virus from the order Mononegavirales AeAV identified from Aedes cell lines were infectious to both Ae. aegypti and Aedes albopictus cells, but not to three mammalian cell lines. To understand the incidence and genetic diversity of AeAV, we assembled 17 coding-complete and two partial genomes of AeAV from available RNA-Seq data. AeAV appears to transmit vertically and be present in laboratory colonies, wild-caught mosquitoes and cell lines worldwide. Phylogenetic analysis of AeAV strains indicates that as the Ae. aegypti mosquito has expanded into the Americas and Asia-Pacific, AeAV has evolved into monophyletic African, American and Asia-Pacific lineages. The endosymbiotic bacterium Wolbachia pipientis restricts positive-sense RNA viruses in Ae. aegypti Re-analysis of a small RNA library of Ae. aegypti cells co-infected with AeAV and Wolbachia produces an abundant RNAi response consistent with persistent virus replication. We found Wolbachia enhances replication of AeAV when compared to a tetracycline cleared cell line, and AeAV modestly reduces DENV replication in vitro The results from our study improve understanding of the diversity and evolution of the virome of Ae. aegypti and adds to previous evidence that shows Wolbachia does not restrict a range of negative strand RNA viruses.IMPORTANCE The mosquito Aedes aegypti transmits a number of arthropod-borne viruses (arboviruses) such as dengue virus and Zika virus. Mosquitoes also harbour insect-specific viruses that may affect replication of pathogenic arboviruses in their body. Currently, however, there are only a handful of insect-specific viruses described from Ae. aegypti in the literature. Here, we characterise a novel negative strand virus, Aedes anphevirus (AeAV). Meta-analysis of Ae. aegypti samples showed that it is present in Ae. aegypti mosquitoes worldwide and is vertically transmitted. Wolbachia transinfected mosquitoes are currently being used in biocontrol as they effectively block transmission of several positive sense RNA viruses in mosquitoes. Our results demonstrate that Wolbachia enhances the replication of AeAV and modestly reduces dengue virus replication in a cell line model. This study expands our understanding of the virome in Ae. aegypti as well as providing insight into the complexity of the Wolbachia virus restriction phenotype.

RevDate: 2018-06-27

Faria VG, Martins NE, Schlötterer C, et al (2018)

Re-adapting to DCV infection without Wolbachia: frequency changes of Drosophila anti-viral alleles can replace endosymbiont protection.

Genome biology and evolution pii:5045875 [Epub ahead of print].

There is now ample evidence that endosymbionts can contribute to host adaptation to environmental challenges. However, how endosymbiont presence affects the adaptive trajectory and outcome of the host is yet largely unexplored. In Drosophila, Wolbachia confers protection to RNA virus infection, an effect that differs between Wolbachia strains and can be targeted by selection. Adaptation to RNA virus infections is mediated by both Wolbachia and the host, raising the question of whether adaptive genetic changes in the host vary with the presence/absence of the endosymbiont. Here, we address this question using a polymorphic D. melanogaster population previously adapted to DCV infection for 35 generations in the presence of Wolbachia, from which we removed the endosymbiont and followed survival over the subsequent 20 generations of infection. After an initial severe drop, survival frequencies upon DCV selection increased significantly, as seen before in the presence of Wolbachia. Whole-genome sequencing, revealed that the major genes involved in the first selection experiment, pastrel and Ubc-E2H, continued to be selected in Wolbachia-free D. melanogaster, with the frequencies of protective alleles being closer to fixation in the absence of Wolbachia. Our results suggest that heterogeneity in Wolbachia infection status may be sufficient to maintain polymorphisms even in the absence of costs.

RevDate: 2018-06-27

Amuzu HE, Tsyganov K, Koh C, et al (2018)

Wolbachia enhances insect-specific flavivirus infection in Aedes aegypti mosquitoes.

Ecology and evolution, 8(11):5441-5454 pii:ECE34066.

Mosquitoes transmit a diverse group of human flaviviruses including West Nile, dengue, yellow fever, and Zika viruses. Mosquitoes are also naturally infected with insect-specific flaviviruses (ISFs), a subgroup of the family not capable of infecting vertebrates. Although ISFs are not medically important, they are capable of altering the mosquito's susceptibility to flaviviruses and may alter host fitness. Wolbachia is an endosymbiotic bacterium of insects that when present in mosquitoes limits the replication of co-infecting pathogens, including flaviviruses. Artificially created Wolbachia-infected Aedes aegypti mosquitoes are being released into the wild in a series of trials around the globe with the hope of interrupting dengue and Zika virus transmission from mosquitoes to humans. Our work investigated the effect of Wolbachia on ISF infection in wild-caught Ae. aegypti mosquitoes from field release zones. All field mosquitoes were screened for the presence of ISFs using general degenerate flavivirus primers and their PCR amplicons sequenced. ISFs were found to be common and widely distributed in Ae. aegypti populations. Field mosquitoes consistently had higher ISF infection rates and viral loads compared to laboratory colony material indicating that environmental conditions may modulate ISF infection in Ae. aegypti. Surprisingly, higher ISF infection rates and loads were found in Wolbachia-infected mosquitoes compared to the Wolbachia-free mosquitoes. Our findings demonstrate that the symbiont is capable of manipulating the mosquito virome and that Wolbachia-mediated viral inhibition is not universal for flaviviruses. This may have implications for the Wolbachia-based DENV control strategy if ISFs confer fitness effects or alter mosquito susceptibility to other flaviviruses.

RevDate: 2018-06-22

Arai H, Hirano T, Akizuki N, et al (2018)

Multiple Infection and Reproductive Manipulations of Wolbachia in Homona magnanima (Lepidoptera: Tortricidae).

Microbial ecology pii:10.1007/s00248-018-1210-4 [Epub ahead of print].

Endosymbiotic bacterium Wolbachia interacts with host in either a mutualistic or parasitic manner. Wolbachia is frequently identified in various arthropod species, and to date, Wolbachia infections have been detected in different insects. Here, we found a triple Wolbachia infection in Homona magnanima, a serious tea pest, and investigated the effects of three infecting Wolbachia strains (wHm-a, -b, and -c) on the host. Starting with the triple-infected host line (Wabc), which was collected in western Tokyo in 1999 and maintained in laboratory, we established an uninfected line (W-) and three singly infected lines (Wa, Wb, and Wc) using antibiotics. Mating experiments with the host lines revealed that only wHm-b induced cytoplasmic incompatibility (CI) in H. magnanima, with the intensities of CI different between the Wb and Wabc lines. Regarding mutualistic effects, wHm-c shortened larval development time and increased pupal weight in both the Wc and Wabc lines to the same extent, whereas no distinct phenotype was observed in lines singly infected with wHm-a. Based on quantitative PCR analysis, Wolbachia density in the Wa line was higher than in the other host lines (p < 0.01, n = 10). Wolbachia density in the Wb line was also higher than in the Wc and Wabc lines, while no difference was observed between the Wc and Wabc lines. These results indicate that the difference in the CI intensity between a single or multiple infection may be attributed to the difference in wHm-b density. However, no correlation was observed between mutualistic effects and Wolbachia density.

RevDate: 2018-07-03

Goindin D, Cannet A, Delannay C, et al (2018)

Screening of natural Wolbachia infection in Aedes aegypti, Aedes taeniorhynchus and Culex quinquefasciatus from Guadeloupe (French West Indies).

Acta tropica, 185:314-317 pii:S0001-706X(18)30269-9 [Epub ahead of print].

Guadeloupe islands are threatened by several mosquito-borne viruses such as Dengue, Chikungunya, Zika and West Nile virus. It appears essential to look for alternative mosquito control methods such as the incompatible insect technique (ITT) aiming at sterilizing wild females by inundative releases of incompatible males. Before considering the implementation of such a strategy, the characterization of genetic diversity of the endocellular bacterium Wolbachia regarding the local mosquito populations is a critical issue. Here, for the first time, we describe the prevalence and diversity of Wolbachia in natural populations of three mosquito species from Guadeloupe: Aedes aegypti, Aedes taeniorhynchus and Culex quinquefasciatus. The detection of Wolbachia in natural Ae. aegypti, Ae. taeniorhynchus and Cx. quinquefasciatus populations was conducted by studying Wolbachia 16S ribosomal RNA gene using a TaqMan quantitative real-time PCR and results were confirmed by conventional PCR and sequencing. In addition, molecular typing of wPip strains in Cx. quinquefasciatus was done by PCR-RFLP. We did not find Wolbachia infection in any of Ae. aegypti and Ae. taeniorhynchus studied populations. Natural Wolbachia infection was detected in Cx. quinquefasciatus with prevalence varying from 79.2% to 95.8%. In addition, no polymorphism was found between the Wolbachia strains infecting Cx. quinquefasciatus specimens, all carrying an infection from the same Wolbachia genetic wPip-I group. These results pave the way for the evaluation of the feasibility of IIT programs to fight against these medically-important mosquito species in Guadeloupe.

RevDate: 2018-06-14

Gloria-Soria A, Chiodo TG, JR Powell (2018)

Lack of Evidence for Natural Wolbachia Infections in Aedes aegypti (Diptera: Culicidae).

Journal of medical entomology pii:5026263 [Epub ahead of print].

Wolbachia is a genus of endosymbiotic bacteria that infects 66% of all insect species. Its major impact on insects is in reproduction: sterility, production of one sex, and/or parthenogenesis. Another effect was discovered when the disease-transmitting mosquito, Aedes aegypti Linnaeus (Diptera: Culicidae), was infected with Wolbachia isolated from Drosophila: infected female mosquitoes became less capable of transmitting diseases such as dengue fever and chikungunya. This has led to releases of Ae. aegypti carrying Wolbachia in an attempt to control disease. An open question is whether there are natural Wolbachia infections of this mosquito. We assayed DNA from 2,663 Ae. aegypti from 27 countries on six continents, 230 from laboratory strains, and 72 Aedes mascarensis MacGregor (Diptera: Culicidae) for presence of Wolbachia DNA. Within the limits of our polymerase chain reaction-based assay, we found no evidence of Wolbachia, suggesting that natural infections of this endosymbiont are unlikely to occur throughout the worldwide distribution of Ae. aegypti.

RevDate: 2018-06-13

Uribe-Alvarez C, Chiquete-Félix N, Morales-García L, et al (2018)

Wolbachia pipientis grows in Saccharomyces cerevisiae evoking early death of the host and deregulation of mitochondrial metabolism.

MicrobiologyOpen [Epub ahead of print].

Wolbachia sp. has colonized over 70% of insect species, successfully manipulating host fertility, protein expression, lifespan, and metabolism. Understanding and engineering the biochemistry and physiology of Wolbachia holds great promise for insect vector-borne disease eradication. Wolbachia is cultured in cell lines, which have long duplication times and are difficult to manipulate and study. The yeast strain Saccharomyces cerevisiae W303 was used successfully as an artificial host for Wolbachia wAlbB. As compared to controls, infected yeast lost viability early, probably as a result of an abnormally high mitochondrial oxidative phosphorylation activity observed at late stages of growth. No respiratory chain proteins from Wolbachia were detected, while several Wolbachia F1 F0 -ATPase subunits were revealed. After 5 days outside the cell, Wolbachia remained fully infective against insect cells.

RevDate: 2018-06-12

Vasconcelos EJR, Billeter SA, Jett LA, et al (2018)

Assessing Cat Flea Microbiomes in Northern and Southern California by 16S rRNA Next-Generation Sequencing.

Vector borne and zoonotic diseases (Larchmont, N.Y.) [Epub ahead of print].

Flea-borne diseases (FBDs) impact both human and animal health worldwide. Because adult fleas are obligately hematophagous and can harbor potential pathogens, fleas act as ectoparasites of vertebrates, as well as zoonotic disease vectors. Cat fleas (Ctenocephalides felis) are important vectors of two zoonotic bacterial genera listed as priority pathogens by the National Institute of Allergy and Infectious Diseases (NIAID-USA): Bartonella spp. and Rickettsia spp., causative agents of bartonelloses and rickettsioses, respectively. In this study, we introduce the first microbiome analysis of C. felis samples from California, determining the presence and abundance of relevant pathogenic genera by characterizing the cat flea microbiome through 16S rRNA next-generation sequencing (16S-NGS). Samples from both northern (NoCal) and southern (SoCal) California were assessed to expand current knowledge regarding FBDs in the state. We identified Rickettsia and Bartonella, as well as the endosymbiont Wolbachia, as the most abundant genera, followed by less abundant taxa. In comparison to our previous study screening Californian cat fleas for rickettsiae using PCR/digestion/sequencing of the ompB gene, the 16S-NGS approach applied herein showed a 95% level of agreement in detecting Rickettsia spp. There was no overall difference in microbiome diversity between NoCal and SoCal samples. Bacterial taxa identified by 16S-NGS in this study may help to improve epidemiological investigations, pathogen surveillance efforts, and clinical diagnostics of FBDs in California and elsewhere.

RevDate: 2018-06-22

Balvín O, Roth S, Talbot B, et al (2018)

Co-speciation in bedbug Wolbachia parallel the pattern in nematode hosts.

Scientific reports, 8(1):8797 pii:10.1038/s41598-018-25545-y.

Wolbachia bacteria, vertically transmitted intracellular endosymbionts, are associated with two major host taxa in which they show strikingly different symbiotic modes. In some taxa of filarial nematodes, where Wolbachia are strictly obligately beneficial to the host, they show complete within- and among-species prevalence as well as co-phylogeny with their hosts. In arthropods, Wolbachia usually are parasitic; if beneficial effects occurs, they can be facultative or obligate, related to host reproduction. In arthropods, the prevalence of Wolbachia varies within and among taxa, and no co-speciation events are known. However, one arthropod species, the common bedbug Cimex lectularius was recently found to be dependent on the provision of biotin and riboflavin by Wolbachia, representing a unique case of Wolbachia providing nutritional and obligate benefits to an arthropod host, perhaps even in a mutualistic manner. Using the presence of presumably functional biotin gene copies, our study demonstrates that the obligate relationship is maintained at least in 10 out of 15 species of the genera Cimex and Paracimex. The remaining five species harboured Wolbachia as well, demonstrating the first known case of 100% prevalence of Wolbachia among higher arthropod taxa. Moreover, we show the predicted co-cladogenesis between Wolbachia and their bedbug hosts, also as the first described case of Wolbachia co-speciation in arthropods.

RevDate: 2018-07-15

Badawi M, Moumen B, Giraud I, et al (2018)

Investigating the Molecular Genetic Basis of Cytoplasmic Sex Determination Caused by Wolbachia Endosymbionts in Terrestrial Isopods.

Genes, 9(6): pii:genes9060290.

In animals, sexual differences between males and females are usually determined by sex chromosomes. Alternatively, sex may also be determined by vertically transmitted intracellular microbial endosymbionts. The best known cytoplasmic sex manipulative endosymbiont is Wolbachia which can, for instance, feminize genetic males into phenotypic females in the terrestrial isopod Armadillidium vulgare. However, the molecular genetic basis of cytoplasmic sex determination is unknown. To identify candidate genes of feminization induced by Wolbachia strain wVulC from A. vulgare, we sequenced the genome of Wolbachia strain wCon from Cylisticus convexus, the most closely related known Wolbachia strain to wVulC that does not induce feminization, and compared it to the wVulC genome. Then, we performed gene expression profiling of the 216 resulting wVulC candidate genes throughout host developmental stages in A. vulgare and the heterologous host C. convexus. We identified a set of 35 feminization candidate genes showing differential expression during host sexual development. Interestingly, 27 of the 35 genes are present in the f element, which is a piece of a feminizing Wolbachia genome horizontally transferred into the nuclear genome of A. vulgare and involved in female sex determination. Assuming that the molecular genetic basis of feminization by Wolbachia and the f element is the same, the 27 genes are candidates for acting as master sex determination genes in A. vulgare females carrying the f element.

RevDate: 2018-06-10

Zhang L, Yun Y, Hu G, et al (2018)

Insights into the bacterial symbiont diversity in spiders.

Ecology and evolution, 8(10):4899-4906 pii:ECE34051.

Most spiders are natural enemies of pests, and it is beneficial for the biological control of pests to learn the relationships between symbionts and their spider hosts. Research on the bacterial communities of insects has been conducted recently, but only a few studies have addressed the bacterial communities of spiders. To obtain a complete overview of the microbial communities of spiders, we examined eight species of spider (Pirata subpiraticus, Agelena difficilis, Artema atlanta, Nurscia albofasciata, Agelena labyrinthica, Ummeliata insecticeps, Dictis striatipes, and Hylyphantes graminicola) with high-throughput sequencing based on the V3 and V4 regions of the 16S rRNA gene. The bacterial communities of the spider samples were dominated by five types of endosymbionts, Wolbachia, Cardinium, Rickettsia, Spiroplasma, and Rickettsiella. The dominant OTUs (operational taxonomic units) from each of the five endosymbionts were analyzed, and the results showed that different spider species were usually dominated by special OTUs. In addition to endosymbionts, Pseudomonas, Sphingomonas, Acinetobacter, Novosphingobium, Aquabacterium, Methylobacterium, Brevundimonas, Rhizobium, Bradyrhizobium, Citrobacter, Arthrobacter, Pseudonocardia, Microbacterium, Lactobacillus, and Lactococcus were detected in spider samples in our study. Moreover, the abundance of Sphingomonas, Methylobacterium, Brevundimonas, and Rhizobium in the spider D. striatipes was significantly higher (p < .05) than the bacterial abundance of these species in seven other spider species. These findings suggest that same as in insects, co-infection of multiple types of endosymbionts is common in the hosts of the Araneae order, and other bacterial taxa also exist in spiders besides the endosymbionts.

RevDate: 2018-06-08

Li J, Wang N, Liu Y, et al (2018)

Proteomics of Nasonia vitripennis and the effects of native Wolbachia infection on N. vitripennis.

PeerJ, 6:e4905 pii:4905.

Background: Nasonia vitripennis, a parasitic wasp, is a good model organism to study developmental and evolutionary genetics and to evaluate the interactions between insect hosts and their symbionts. Wolbachia may be the most prevalent endosymbiont among insect species due to their special ability to improve the fitness of the infected hosts. Transinfection of bacteria or fungi could substantially alter the expression of host immune system components. However, few studies have focused on the effects of native Wolbachia infection. Accordingly, in this study, we evaluated the proteomics of N. vitripennis following Wolbachia infection.

Methods: We studied the proteomics of N. vitripennis following native Wolbachia infection and in antibiotic-treated Wolbachia-free samples using isobaric tags for relative and absolute quantification-liquid chromatography tandem mass spectrometry, accompanying with some ecological experiments.

Results: In total, 3,096 proteins were found to be associated with a wide range of biological processes, molecular functions, and cellular components. Interestingly, there were few significant changes in immune or reproductive proteins between samples with and without Wolbachia infection. Differentially expressed proteins were involved in the binding process, catalytic activity, and the metabolic process, as confirmed by quantitative reverse transcription polymerase chain reaction.

Discussion: Invasion of any pathogen or bacterium within a short time can cause an immunoreaction in the host. Our results implied that during the long process of coexistence, the immune system of the host was not as sensitive as when the symbiont initially infected the host, implying that the organisms had gradually adjusted to cohabitation.

RevDate: 2018-07-08

Hornok S, Horváth G, Takács N, et al (2018)

Molecular evidence of a badger-associated Ehrlichia sp., a Candidatus Neoehrlichia lotoris-like genotype and Anaplasma marginale in dogs.

Ticks and tick-borne diseases, 9(5):1302-1309.

The family Anaplasmataceae contains pathogenic and endosymbiotic bacteria of veterinary-medical importance. In this study, 90 blood samples from rural dogs, five blood samples from road-killed European badgers and 34 ticks, i.e. 27 Ixodes (Pholeoixodes) canisuga, six I. (Ph.) hexagonus and one Haemaphysalis concinna collected from the badgers were molecularly analysed for members of Anaplasmataceae. Apart from the molecular evidence of Anaplasma phagocytophilum in one dog and Wolbachia sp. associated with Dirofilaria repens in five dogs, four species/genotypes not yet known to occur in canine hosts have also been found. These included A. marginale in two dogs, a badger-associated Ehrlichia sp. in one dog, a Candidatus Neoehrlichia lotoris-like genotype in six dogs and the DNA of arthropod-associated wolbachiae in three dogs. In two badgers the DNA from the Candidatus N. lotoris-like genotype was identified. Among ticks, four I. canisuga carried the DNA of the above badger-associated Ehrlichia sp., one I. canisuga contained the Candidatus N. lotoris-like genotype, and in H. concinna Wolbachia DNA was present. In conclusion, results shown here should be interpreted as the first molecular evidence for exposure of dogs to three members of Anaplasmataceae, i.e. A. marginale, a badger-associated Ehrlichia sp. and a Candidatus N. lotoris-like agent. The presence of DNA in the blood of relevant animals may also indicate susceptibility to these bacteria, but in support of this, further studies are needed.

RevDate: 2018-06-08

Anders KL, Indriani C, Ahmad RA, et al (2018)

The AWED trial (Applying Wolbachia to Eliminate Dengue) to assess the efficacy of Wolbachia-infected mosquito deployments to reduce dengue incidence in Yogyakarta, Indonesia: study protocol for a cluster randomised controlled trial.

Trials, 19(1):302 pii:10.1186/s13063-018-2670-z.

BACKGROUND: Dengue and other arboviruses transmitted by Aedes aegypti mosquitoes, including Zika and chikungunya, present an increasing public health challenge in tropical regions. Current vector control strategies have failed to curb disease transmission, but continue to be employed despite the absence of robust evidence for their effectiveness or optimal implementation. The World Mosquito Program has developed a novel approach to arbovirus control using Ae. aegypti stably transfected with Wolbachia bacterium, with a significantly reduced ability to transmit dengue, Zika and chikungunya in laboratory experiments. Modelling predicts this will translate to local elimination of dengue in most epidemiological settings. This study protocol describes the first trial to measure the efficacy of Wolbachia in reducing dengue virus transmission in the field.

METHODS/DESIGN: The study is a parallel, two-arm, non-blinded cluster randomised controlled trial conducted in a single site in Yogyakarta, Indonesia. The aim is to determine whether large-scale deployment of Wolbachia-infected Ae. aegypti mosquitoes leads to a measurable reduction in dengue incidence in treated versus untreated areas. The primary endpoint is symptomatic, virologically confirmed dengue virus infection of any severity. The 26 km2 study area was subdivided into 24 contiguous clusters, allocated randomly 1:1 to receive Wolbachia deployments or no intervention. We use a novel epidemiological study design, the cluster-randomised test-negative design trial, in which dengue cases and arbovirus-negative controls are sampled concurrently from among febrile patients presenting to a network of primary care clinics, with case or control status classified retrospectively based on the results of laboratory diagnostic testing. Efficacy is estimated from the odds ratio of Wolbachia exposure distribution (probability of living in a Wolbachia-treated area) among virologically confirmed dengue cases compared to test-negative controls. A secondary per-protocol analysis allows for individual Wolbachia exposure levels to be assessed to account for movements outside the cluster and the heterogeneity in local Wolbachia prevalence among treated clusters.

DISCUSSION: The findings from this study will provide the first experimental evidence for the efficacy of Wolbachia in reducing dengue incidence. Together with observational evidence that is accumulating from pragmatic deployments of Wolbachia in other field sites, this will provide valuable data to estimate the effectiveness of this novel approach to arbovirus control, inform future cost-effectiveness estimates, and guide plans for large-scale deployments in other endemic settings.

TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT03055585 . Registered on 14 February 2017.

RevDate: 2018-06-08

Dahmani M, Tahir D, Cabre O, et al (2018)

Prevalence of Anaplasmataceae and Filariidae species in unowned and military dogs in New Caledonia.

Veterinary medicine and science, 4(2):140-149.

Dogs are competent reservoir hosts of several zoonotic agents, including Filariidae nematodes and Anaplasmataceae family bacteria. The latter family unites human and veterinary pathogens (Anaplasma, Ehrlichia and Neorickettsia bacteria) with Wolbachia, some of which are obligatory endosymbionts of pathogenic filarial nematodes. The epidemiology of Anaplasmataceae and Filariidae species infecting dogs living in kennels in New Caledonia was studied. 64 EDTA blood samples were screened for the presence of Anaplasmataceae and filarial nematodes. Molecular study was conducted using primers and probe targeting the of 23S rRNA long fragment of Anaplasmataceae species. Next, all blood sample was screened for the presence of Filariidae species targeting the primers and probe targeting the COI gene, as well as primers targeting the COI and 5S rRNA genes of all filarial worms. Anaplasma platys was identified in 8/64 (12.5, 95% confidence interval [CI]: 4.4-20.6%) and Wolbachia endosymbiont of Dirofilaria immitis in 8/64 (12.5%, CI: 4.4-20.6%). Filariidae species investigation was performed and showed that 11/64 (17.2%, CI: 7.9-26.4%) dogs were infected with D. immitis, whereas, 2/64 (3.1%, CI: 0.0-7.3%) were infected with Acanthocheilonema reconditum. Finally, we checked the occurrence of co-infection between Anaplasmataceae and Filariidae species. Co-occurrence with Wolbachia endosymbiont of D. immitis was observed in seven dogs, one dog was co-infected with A. platys and A. reconditum and another was co-infected with Wolbachia endosymbiont of D. immitis and A. reconditum. These results are the first report of Anaplasmataceae and Filariidae occurring in dogs in New Caledonia.

RevDate: 2018-05-31

Ote M, D Yamamoto (2018)

The Wolbachia protein TomO interacts with a host RNA to induce polarization defects in Drosophila oocytes.

Archives of insect biochemistry and physiology [Epub ahead of print].

Wolbachia is an endosymbiont prevalent in arthropods. To maximize its transmission thorough the female germline, Wolbachia induces in infected hosts male-to-female transformation, male killing, parthenogenesis, and cytoplasmic incompatibility, depending on the host species and Wolbachia strain involved. However, the molecular mechanisms underlying these host manipulations by Wolbachia remain largely unknown. The Wolbachia strain wMel, an inhabitant of Drosophila melanogaster, impairs host oogenesis only when transplanted into a heterologous host, for example, Drosophila simulans. We found that egg polarity defects induced by wMel infection in D. simulans can be recapitulated in the natural host D. melanogaster by transgenic overexpression of a variant of the Wolbachia protein Toxic manipulator of oogenesis (TomO), TomOwMel∆HS , in the female germline. RNA immunoprecipitation assays demonstrated that TomO physically associates with orb mRNA, which, as a result, fails to interact with the translation repressor Cup. This leads to precocious translation of Orb, a posterior determinant, and thereby to the misspecification of oocytes and accompanying polarity defects. We propose that the ability of TomO to bind to orb mRNA might provide a means for Wolbachia to enter the oocyte located at the posterior end of the egg chamber, thereby accomplishing secure maternal transmission thorough the female germline.

RevDate: 2018-05-30

O'Neill SL (2018)

The Use of Wolbachia by the World Mosquito Program to Interrupt Transmission of Aedes aegypti Transmitted Viruses.

Advances in experimental medicine and biology, 1062:355-360.

The biological control of mosquito transmission by the use of the naturally occurring insect-specific bacterial endosymbiont Wolbachia has been successfully tested in small field trials. The approach has been translated successfully to larger field sites in Townsville, Australia and expanded to more than 10 countries through the Eliminate Dengue Program. The broader application of the program beyond limiting the transmission of dengue and including other Aedes aegypti borne mosquitoes has seen the program growing into a global not-for-profit initiative to be known as the World Mosquito Program.

RevDate: 2018-06-01

Perry KD, Baker GJ, Powis KJ, et al (2018)

Cryptic Plutella species show deep divergence despite the capacity to hybridize.

BMC evolutionary biology, 18(1):77 pii:10.1186/s12862-018-1183-4.

BACKGROUND: Understanding genomic and phenotypic diversity among cryptic pest taxa has important implications for the management of pests and diseases. The diamondback moth, Plutella xylostella L., has been intensively studied due to its ability to evolve insecticide resistance and status as the world's most destructive pest of brassicaceous crops. The surprise discovery of a cryptic species endemic to Australia, Plutella australiana Landry & Hebert, raised questions regarding the distribution, ecological traits and pest status of the two species, the capacity for gene flow and whether specific management was required. Here, we collected Plutella from wild and cultivated brassicaceous plants from 75 locations throughout Australia and screened 1447 individuals to identify mtDNA lineages and Wolbachia infections. We genotyped genome-wide SNP markers using RADseq in coexisting populations of each species. In addition, we assessed reproductive compatibility in crossing experiments and insecticide susceptibility phenotypes using bioassays.

RESULTS: The two Plutella species coexisted on wild brassicas and canola crops, but only 10% of Plutella individuals were P. australiana. This species was not found on commercial Brassica vegetable crops, which are routinely sprayed with insecticides. Bioassays found that P. australiana was 19-306 fold more susceptible to four commonly-used insecticides than P. xylostella. Laboratory crosses revealed that reproductive isolation was incomplete but directionally asymmetric between the species. However, genome-wide nuclear SNPs revealed striking differences in genetic diversity and strong population structure between coexisting wild populations of each species. Nuclear diversity was 1.5-fold higher in P. australiana, yet both species showed limited variation in mtDNA. Infection with a single Wolbachia subgroup B strain was fixed in P. australiana, suggesting that a selective sweep contributed to low mtDNA diversity, while a subgroup A strain infected just 1.5% of P. xylostella.

CONCLUSIONS: Despite sympatric distributions and the capacity to hybridize, strong genomic and phenotypic divergence exists between these Plutella species that is consistent with contrasting colonization histories and reproductive isolation after secondary contact. Although P. australiana is a potential pest of brassicaceous crops, it is of secondary importance to P. xylostella.

RevDate: 2018-05-29

Ali H, Muhammad A, Y Hou (2018)

Infection Density Dynamics and Phylogeny of Wolbachia Associated with Coconut Hispine Beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), by Multilocus Sequence Type (MLST) Genotyping.

Journal of microbiology and biotechnology, 28(5):796-808.

The intracellular bacterium Wolbachia pipientis is widespread in arthropods. Recently, possibilities of novel Wolbachia-mediated hosts, their distribution, and natural rate have been anticipated, and the coconut leaf beetle Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), which has garnered attention as a serious pest of palms, was subjected to this interrogation. By adopting Wolbachia surface protein (wsp) and multilocus sequence type (MLST) genotypic systems, we determined the Wolbachia infection density within host developmental stages, body parts, and tissues, and the results revealed that all the tested samples of B. longissima were infected with the same Wolbachia strain (wLog), suggesting complete vertical transmission. The MLST profile elucidated two new alleles (ftsZ-234 and coxA-266) that define a new sequence type (ST-483), which indicates the particular genotypic association of B. longissima and Wolbachia. The quantitative real-time PCR analysis revealed a higher infection density in the eggs and adult stage, followed by the abdomen and reproductive tissues, respectively. However, no significant differences were observed in the infection density between sexes. Moreover, the wsp and concatenated MLST alignment analysis of this study with other known Wolbachia-mediated arthropods revealed similar clustering with distinct monophyletic supergroup B. This is the first comprehensive report on the prevalence, infection dynamics, and phylogeny of the Wolbachia endosymbiont in B. longissima, which demonstrated that Wolbachia is ubiquitous across all developmental stages and distributed in the entire body of B. longissima. Understanding the Wolbachia infection dynamics would provide useful insight to build a framework for future investigations, understand its impacts on host physiology, and exploit it as a potential biocontrol agent.

RevDate: 2018-05-31

Opatovsky I, Santos-Garcia D, Ruan Z, et al (2018)

Modeling trophic dependencies and exchanges among insects' bacterial symbionts in a host-simulated environment.

BMC genomics, 19(1):402 pii:10.1186/s12864-018-4786-7.

BACKGROUND: Individual organisms are linked to their communities and ecosystems via metabolic activities. Metabolic exchanges and co-dependencies have long been suggested to have a pivotal role in determining community structure. In phloem-feeding insects such metabolic interactions with bacteria enable complementation of their deprived nutrition. The phloem-feeding whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) harbors an obligatory symbiotic bacterium, as well as varying combinations of facultative symbionts. This well-defined bacterial community in B. tabaci serves here as a case study for a comprehensive and systematic survey of metabolic interactions within the bacterial community and their associations with documented occurrences of bacterial combinations. We first reconstructed the metabolic networks of five common B. tabaci symbionts genera (Portiera, Rickettsia, Hamiltonella, Cardinium and Wolbachia), and then used network analysis approaches to predict: (1) species-specific metabolic capacities in a simulated bacteriocyte-like environment; (2) metabolic capacities of the corresponding species' combinations, and (3) dependencies of each species on different media components.

RESULTS: The predictions for metabolic capacities of the symbionts in the host environment were in general agreement with previously reported genome analyses, each focused on the single-species level. The analysis suggests several previously un-reported routes for complementary interactions and estimated the dependency of each symbiont in specific host metabolites. No clear association was detected between metabolic co-dependencies and co-occurrence patterns.

CONCLUSIONS: The analysis generated predictions for testable hypotheses of metabolic exchanges and co-dependencies in bacterial communities and by crossing them with co-occurrence profiles, contextualized interaction patterns into a wider ecological perspective.

RevDate: 2018-06-24

Bakovic V, Schebeck M, Telschow A, et al (2018)

Spatial spread of Wolbachia in Rhagoletis cerasi populations.

Biology letters, 14(5):.

The bacterial endosymbiont Wolbachia has been used to control insect pests owing to its ability to manipulate their life history and suppress infectious diseases. Therefore, knowledge on Wolbachia dynamics in natural populations is fundamental. The European cherry fruit fly, Rhagoletis cerasi, is infected with the Wolbachia strain wCer2, mainly present in southern and central European populations, and is currently spreading into wCer2-uninfected populations driven by high unidirectional cytoplasmic incompatibility. Here, we describe the distribution of wCer2 along two transition zones where the infection is spreading into wCer2-uninfected R. cerasi populations. Fine-scale sampling of 19 populations in the Czech Republic showed a smooth decrease of wCer2 frequency from south to north within a distance of less than 20 km. Sampling of 12 Hungarian populations, however, showed a sharp decline of wCer2 infection frequency within a few kilometres. We fitted a standard wave equation to our empirical data and estimated a Wolbachia wave speed of 1.9 km yr-1 in the Czech Republic and 1.0 km yr-1 in Hungary. Considering the univoltine life cycle and limited dispersal ability of R. cerasi, our study highlights a rapid Wolbachia spread in natural host populations.

RevDate: 2018-07-09

Stouthamer CM, Kelly S, MS Hunter (2018)

Enrichment of low-density symbiont DNA from minute insects.

Journal of microbiological methods, 151:16-19 pii:S0167-7012(18)30142-8 [Epub ahead of print].

Symbioses between bacteria and insects are often associated with changes in important biological traits that can significantly affect host fitness. To a large extent, studies of these interactions have been based on physiological changes or induced phenotypes in the host, and the genetic mechanisms by which symbionts interact with their hosts have only recently become better understood. Learning about symbionts has been challenging in part due to difficulties such as obtaining enough high quality genomic material for high throughput sequencing technology, especially for symbionts present in low titers, and in small or difficult to rear non-model hosts. Here we introduce a new method that substantially increases the yield of bacterial DNA in minute arthropod hosts, and requires less starting material relative to previous published methods.

RevDate: 2018-05-25

Schultz MJ, Tan AL, Gray CN, et al (2018)

Wolbachia wStri Blocks Zika Virus Growth at Two Independent Stages of Viral Replication.

mBio, 9(3): pii:mBio.00738-18.

Mosquito-transmitted viruses are spread globally and present a great risk to human health. Among the many approaches investigated to limit the diseases caused by these viruses are attempts to make mosquitos resistant to virus infection. Coinfection of mosquitos with the bacterium Wolbachia pipientis from supergroup A is a recent strategy employed to reduce the capacity for major vectors in the Aedes mosquito genus to transmit viruses, including dengue virus (DENV), Chikungunya virus (CHIKV), and Zika virus (ZIKV). Recently, a supergroup B Wolbachia wStri, isolated from Laodelphax striatellus, was shown to inhibit multiple lineages of ZIKV in Aedes albopictus cells. Here, we show that wStri blocks the growth of positive-sense RNA viruses DENV, CHIKV, ZIKV, and yellow fever virus by greater than 99.9%. wStri presence did not affect the growth of the negative-sense RNA viruses LaCrosse virus or vesicular stomatitis virus. Investigation of the stages of the ZIKV life cycle inhibited by wStri identified two distinct blocks in viral replication. We found a reduction of ZIKV entry into wStri-infected cells. This was partially rescued by the addition of a cholesterol-lipid supplement. Independent of entry, transfected viral genome was unable to replicate in Wolbachia-infected cells. RNA transfection and metabolic labeling studies suggested that this replication defect is at the level of RNA translation, where we saw a 66% reduction in mosquito protein synthesis in wStri-infected cells. This study's findings increase the potential for application of wStri to block additional arboviruses and also identify specific blocks in viral infection caused by Wolbachia coinfection.IMPORTANCE Dengue, Zika, and yellow fever viruses are mosquito-transmitted diseases that have spread throughout the world, causing millions of infections and thousands of deaths each year. Existing programs that seek to contain these diseases through elimination of the mosquito population have so far failed, making it crucial to explore new ways of limiting the spread of these viruses. Here, we show that introduction of an insect symbiont, Wolbachia wStri, into mosquito cells is highly effective at reducing yellow fever virus, dengue virus, Zika virus, and Chikungunya virus production. Reduction of virus replication was attributable to decreases in entry and a strong block of virus gene expression at the translational level. These findings expand the potential use of Wolbachia wStri to block viruses and identify two separate steps for limiting virus replication in mosquitos that could be targeted via microbes or other means as an antiviral strategy.

RevDate: 2018-06-08

Funkhouser-Jones LJ, van Opstal EJ, Sharma A, et al (2018)

The Maternal Effect Gene Wds Controls Wolbachia Titer in Nasonia.

Current biology : CB, 28(11):1692-1702.e6.

Maternal transmission of intracellular microbes is pivotal in establishing long-term, intimate symbioses. For germline microbes that exert negative reproductive effects on their hosts, selection can theoretically favor the spread of host genes that counteract the microbe's harmful effects. Here, we leverage a major difference in bacterial (Wolbachia pipientis) titers between closely related wasp species with forward genetic, transcriptomic, and cytological approaches to map two quantitative trait loci that suppress bacterial titers via a maternal effect. Fine mapping and knockdown experiments identify the gene Wolbachia density suppressor (Wds), which dominantly suppresses bacterial transmission from mother to embryo. Wds evolved by lineage-specific non-synonymous changes driven by positive selection. Collectively, our findings demonstrate that a genetically simple change arose by positive Darwinian selection in less than a million years to regulate maternally transmitted bacteria via a dominant, maternal effect gene.

RevDate: 2018-07-13

Flores HA, SL O'Neill (2018)

Controlling vector-borne diseases by releasing modified mosquitoes.

Nature reviews. Microbiology, 16(8):508-518.

Aedes mosquito-transmitted diseases, such as dengue, Zika and chikungunya, are becoming major global health emergencies while old threats, such as yellow fever, are re-emerging. Traditional control methods, which have focused on reducing mosquito populations through the application of insecticides or preventing breeding through removal of larval habitat, are largely ineffective, as evidenced by the increasing global disease burden. Here, we review novel mosquito population reduction and population modification approaches with a focus on control methods based on the release of mosquitoes, including the release of Wolbachia-infected mosquitoes and strategies to genetically modify the vector, that are currently under development and have the potential to contribute to a reversal of the current alarming disease trends.

RevDate: 2018-05-26

Lindsey ARI, Kelkar YD, Wu X, et al (2018)

Comparative genomics of the miniature wasp and pest control agent Trichogramma pretiosum.

BMC biology, 16(1):54 pii:10.1186/s12915-018-0520-9.

BACKGROUND: Trichogrammatids are minute parasitoid wasps that develop within other insect eggs. They are less than half a millimeter long, smaller than some protozoans. The Trichogrammatidae are one of the earliest branching families of Chalcidoidea: a diverse superfamily of approximately half a million species of parasitoid wasps, proposed to have evolved from a miniaturized ancestor. Trichogramma are frequently used in agriculture, released as biological control agents against major moth and butterfly pests. Additionally, Trichogramma are well known for their symbiotic bacteria that induce asexual reproduction in infected females. Knowledge of the genome sequence of Trichogramma is a major step towards further understanding its biology and potential applications in pest control.

RESULTS: We report the 195-Mb genome sequence of Trichogramma pretiosum and uncover signatures of miniaturization and adaptation in Trichogramma and related parasitoids. Comparative analyses reveal relatively rapid evolution of proteins involved in ribosome biogenesis and function, transcriptional regulation, and ploidy regulation. Chalcids also show loss or especially rapid evolution of 285 gene clusters conserved in other Hymenoptera, including many that are involved in signal transduction and embryonic development. Comparisons between sexual and asexual lineages of Trichogramma pretiosum reveal that there is no strong evidence for genome degradation (e.g., gene loss) in the asexual lineage, although it does contain a lower repeat content than the sexual lineage. Trichogramma shows particularly rapid genome evolution compared to other hymenopterans. We speculate these changes reflect adaptations to miniaturization, and to life as a specialized egg parasitoid.

CONCLUSIONS: The genomes of Trichogramma and related parasitoids are a valuable resource for future studies of these diverse and economically important insects, including explorations of parasitoid biology, symbiosis, asexuality, biological control, and the evolution of miniaturization. Understanding the molecular determinants of parasitism can also inform mass rearing of Trichogramma and other parasitoids for biological control.

RevDate: 2018-07-09
CmpDate: 2018-07-09

Schebeck M, Feldkirchner L, Marín B, et al (2018)

Reproductive Manipulators in the Bark Beetle Pityogenes chalcographus (Coleoptera: Curculionidae)-The Role of Cardinium, Rickettsia, Spiroplasma, and Wolbachia.

Journal of insect science (Online), 18(3):.

Heritable bacterial endosymbionts can alter the biology of numerous arthropods. They can influence the reproductive outcome of infected hosts, thus affecting the ecology and evolution of various arthropod species. The spruce bark beetle Pityogenes chalcographus (L.) (Coleoptera: Curculionidae: Scolytinae) was reported to express partial, unidirectional crossing incompatibilities among certain European populations. Knowledge on the background of these findings is lacking; however, bacterial endosymbionts have been assumed to manipulate the reproduction of this beetle. Previous work reported low-density and low-frequency Wolbachia infections of P. chalcographus but found it unlikely that this infection results in reproductive alterations. The aim of this study was to test the hypothesis of an endosymbiont-driven incompatibility, other than Wolbachia, reflected by an infection pattern on a wide geographic scale. We performed a polymerase chain reaction (PCR) screening of 226 individuals from 18 European populations for the presence of the endosymbionts Cardinium, Rickettsia, and Spiroplasma, and additionally screened these individuals for Wolbachia. Positive PCR products were sequenced to characterize these bacteria. Our study shows a low prevalence of these four endosymbionts in P. chalcographus. We detected a yet undescribed Spiroplasma strain in a single individual from Greece. This is the first time that this endosymbiont has been found in a bark beetle. Further, Wolbachia was detected in three beetles from two Scandinavian populations and two new Wolbachia strains were described. None of the individuals analyzed were infected with Cardinium and Rickettsia. The low prevalence of bacteria found here does not support the hypothesis of an endosymbiont-driven reproductive incompatibility in P. chalcographus.

RevDate: 2018-06-27

Kriesner P, AA Hoffmann (2018)

Rapid spread of a Wolbachia infection that does not affect host reproduction in Drosophila simulans cage populations.

Evolution; international journal of organic evolution [Epub ahead of print].

Wolbachia endosymbionts that are maternally inherited can spread rapidly in host populations through inducing sterility in uninfected females, but some Wolbachia infections do not influence host reproduction yet still persist. These infections are particularly interesting because they likely represent mutualistic endosymbionts, spreading by increasing host fitness. Here, we document such a spread in the wAu infection of Drosophila simulans. By establishing multiple replicate cage populations, we show that wAu consistently increased from an intermediate frequency to near fixation, representing an estimated fitness advantage of around 20% for infected females. The effective population size in the cages was estimated from SNP markers to be around a few thousand individuals, precluding large effects of genetic drift in the populations. The exact reasons for the fitness advantage are unclear but viral protection and nutritional benefits are two possibilities.

RevDate: 2018-05-18

Hu W, Kuang F, Lu Z, et al (2018)

Killing Effects of an Isolated Serratia marcescens KH-001 on Diaphorina citri via Lowering the Endosymbiont Numbers.

Frontiers in microbiology, 9:860.

Huanglongbing (HLB) is the most devastating citrus disease worldwide, and suppression of the Asian citrus psyllid (Diaphorina citri) is regarded as an effective method to inhibit the spread of HLB. In this study, we isolated a strain named as Serratia marcescens KH-001 from D. citri nymphs suffering from disease, and evaluated its killing effect on D. citri via toxicity test and effect on microbial community in D. citri using high-throughput sequencing. Our results indicated that S. marcescens KH-001 could effectively kill 83% of D. citri nymphs, while the fermentation products of S. marcescens KH-001 only killed 40% of the D. citrinymphs. High-throughput sequencing results indicated that the S. marcescens KH-001 increased the OTU numbers from 62.5 (PBS buffer) to 81.5, while significantly lowered the Shannon index compared with Escherichia coli DH5α (group E) (p < 0.05). OTU analysis showed that the S. marcescens KH-001 had significantly reduced the relative abundance of endosymbionts Wolbachia, Profftella, and Carsonella in group S compared with that in other groups (p < 0.05). Therefore, the direct killing effect of the fermentation products of S. marcescens KH-001 and the indirect effect via reducing the numbers of endosymbionts (Wolbachia, Profftella, and Carsonella) of D. citri endow S. marcescens KH-001 a sound killing effect on D. citri. Further work need to do before this strain is used as a sound biological control agents.

RevDate: 2018-05-17

Duplouy A, EA Hornett (2018)

Uncovering the hidden players in Lepidoptera biology: the heritable microbial endosymbionts.

PeerJ, 6:e4629 pii:4629.

The Lepidoptera is one of the most widespread and recognisable insect orders. Due to their remarkable diversity, economic and ecological importance, moths and butterflies have been studied extensively over the last 200 years. More recently, the relationship between Lepidoptera and their heritable microbial endosymbionts has received increasing attention. Heritable endosymbionts reside within the host's body and are often, but not exclusively, inherited through the female line. Advancements in molecular genetics have revealed that host-associated microbes are both extremely prevalent among arthropods and highly diverse. Furthermore, heritable endosymbionts have been repeatedly demonstrated to play an integral role in many aspects of host biology, particularly host reproduction. Here, we review the major findings of research of heritable microbial endosymbionts of butterflies and moths. We promote the Lepidoptera as important models in the study of reproductive manipulations employed by heritable endosymbionts, with the mechanisms underlying male-killing and feminisation currently being elucidated in moths and butterflies. We also reveal that the vast majority of research undertaken of Lepidopteran endosymbionts concerns Wolbachia. While this highly prevalent bacterium is undoubtedly important, studies should move towards investigating the presence of other, and interacting endosymbionts, and we discuss the merits of examining the microbiome of Lepidoptera to this end. We finally consider the importance of understanding the influence of endosymbionts under global environmental change and when planning conservation management of endangered Lepidoptera species.

RevDate: 2018-06-29

Katsuma S, Kiuchi T, Kawamoto M, et al (2018)

Unique sex determination system in the silkworm, Bombyx mori: current status and beyond.

Proceedings of the Japan Academy. Series B, Physical and biological sciences, 94(5):205-216.

The silkworm Bombyx mori has been used for silk production for over 5,000 years. In addition to its contribution to sericulture, B. mori has played an important role in the field of genetics. Classical genetic studies revealed that a gene(s) with a strong feminizing activity is located on the W chromosome, but this W-linked feminizing gene, called Feminizer (Fem), had not been cloned despite more than 80 years of study. In 2014, we discovered that Fem is a precursor of a single W chromosome-derived PIWI-interacting RNA (piRNA). Fem-derived piRNA binds to PIWI protein, and this complex then cleaves the mRNA of the Z-linked Masculinizer (Masc) gene, which encodes a protein required for both masculinization and dosage compensation. These findings showed that the piRNA-mediated interaction between the two sex chromosomes is the primary signal for the sex determination cascade in B. mori. In this review, we summarize the history, current status, and perspective of studies on sex determination and related topics in B. mori.

RevDate: 2018-05-29

Morçiçek B, Taskin BG, Doğaç E, et al (2018)

Evidence of natural Wolbachia infections and molecular identification of field populations of Culex pipiens complex (Diptera: Culicidae) mosquitoes in western Turkey.

Journal of vector ecology : journal of the Society for Vector Ecology, 43(1):44-51.

Establishing reliable risk projection information about the distribution pattern of members of the Culex pipiens complex is of particular interest, as these mosquitoes are competent vectors for certain disease-causing pathogens. Wolbachia, a maternally inherited bacterial symbiont, are distributed in various arthropod species and can induce cytoplasmic incompatibility, i.e., reduced egg hatch, in certain crosses. It is being considered as a tool for population control of mosquito disease vectors. The Aegean region is characterized by highly populated, rural, and agricultural areas and is also on the route of the migratory birds. In this study, a fragment of the 658 bp of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene, which includes the barcode region, was employed to differentiate Cx. pipiens complex species found in this region. Moreover, for the first time, the prevalence of Wolbachia endobacteria in these natural populations was examined using PCR amplification of a specific wsp gene. Our results revealed a widespread (more than 90%, n=121) presence of the highly efficient West Nile virus vector Cx. quinquefasciatus in the region. We also found that Wolbachia infection is widespread; the average prevalence was 62% in populations throughout the region. This study provided valuable information about the composition of Cx. pipiens complex mosquitoes and the prevalence of Wolbachia infection in these populations in the Aegean region. This information will be helpful in tracking mosquito-borne diseases and designing and implementing Wolbachia-based control strategies in the region.

RevDate: 2018-05-24

Ant TH, SP Sinkins (2018)

A Wolbachia triple-strain infection generates self-incompatibility in Aedes albopictus and transmission instability in Aedes aegypti.

Parasites & vectors, 11(1):295 pii:10.1186/s13071-018-2870-0.

BACKGROUND: Artificially-introduced transinfections of the intracellular bacterium Wolbachia pipientis have the potential to reduce the vectorial capacity of mosquito populations for viruses such as dengue and chikungunya. Aedes albopictus has two native strains of Wolbachia, but their replacement with the non-native wMel strain blocks transmission of both viruses. The pattern of cytoplasmic incompatiiblity generated by wMel with wild-types is bidirectional. Novel-plus-native-strain co-infection is predicted to lead to a more efficient population spread capacity; from a bi-directional to a uni-directional cytoplasmic incompatibility (CI) model.

RESULTS: A novel-plus-native-strain triple-infection in Ae. albopictus (wAlbAwAlbBwMel) was generated. Although triple-infected females were fully reproductively viable with uninfected males, they displayed self-incompatibility. qPCR of specific strains in dissected tissues suggested that this may be due to the displacement of one of the native strains (wAlbA) from the ovaries of triple-infected females. When the triple strain infection was transferred into Aedes aegypti it displayed an unexpectedly low level of transmission fidelity of the three strains in this species.

CONCLUSIONS: These results suggest that combining Wolbachia strains can lead to co-infection interactions that can affect outcomes of CI and maternal transmission.

RevDate: 2018-06-01

Karimian F, Vatandoost H, Rassi Y, et al (2018)

wsp-based analysis of Wolbachia strains associated with Phlebotomus papatasi and P. sergenti (Diptera: Psychodidae) main cutaneous leishmaniasis vectors, introduction of a new subgroup wSerg.

Pathogens and global health, 112(3):152-160.

Sand flies of Phlebotomus papatasi and P. sergenti are the main vectors of cutaneous leishmanisis (CL) in the old world. We aimed to screen Iranian P. papatasi and P. sergenti for their natural infections with Wolbachia and to determine their phylogenetic association with other species. Wolbachia surface protein (wsp) gene was PCR amplified from DNA extracted from Phlebotomus species, sequenced, and were analysed in combination with wsp sequences related to Phelebtominae and other insects. All Wolbachia-infecting Iranian sand flies of P. papatasi and P. sergenti were classified in the Supergroup A., Wolbachia isolated from P. sergenti were clustered in a new subgroup within Supergroup A so-called wSreg. The Wolbachia strains identified from the P. papatasi clustered mainly in the subgroup wPap and partly in wSerg. Multiple Wholbachia infection within a single population of P.papatasi warrants investigation on existence and intensity of cytoplasmic incompatibility between the wPap and wSerg subgroups.

RevDate: 2018-05-07

Zheng Y, Bi J, Hou MY, et al (2018)

Ocnus is essential for male germ cell development in Drosophila melanogaster.

Insect molecular biology [Epub ahead of print].

The ocnus (ocn) gene encodes a protein abundant in the testes, implying its role in testis development. When Drosophila melanogaster is infected with the endosymbiont wMel Wolbachia, which affects the spermatogenesis of its hosts, ocn is downregulated in the third-instar larval testes, suggesting a role of ocn in spermatogenesis. In this study, we knocked down ocn in the testes and found that the hatch rates of embryos derived from ocn-knockdown males were significantly decreased, and 84.38% of the testes were much smaller in comparison to controls. Analysis of the smaller testes showed no germ cells but they had an extended hub. Using RNA-sequencing (RNA-Seq), we identified 69 genes with at least a twofold change (q-value < 5%) in their expression after ocn knockdown; of these, eight testes-specific and three reproduction-related genes were verified to be significantly downregulated using quantitative reverse transcription-PCR. Three genes (orientation disruptor, p24-2 and CG13541) were also significantly downregulated in the presence of Wolbachia. Furthermore, 98 genes were not expressed when ocn was knocked down in testes. These results suggest that ocn plays a crucial role in male germ cell development in Drosophila, possibly by regulating the expression of multiple spermatogenesis-related genes. Our data provide important information to help understand the molecular regulatory mechanisms underlying spermatogenesis.

RevDate: 2018-05-11

Dittmer J, D Bouchon (2018)

Feminizing Wolbachia influence microbiota composition in the terrestrial isopod Armadillidium vulgare.

Scientific reports, 8(1):6998 pii:10.1038/s41598-018-25450-4.

Wolbachia are widespread heritable endosymbionts of arthropods notorious for their profound effects on host fitness as well as for providing protection against viruses and eukaryotic parasites, indicating that they can interact with other microorganisms sharing the same host environment. Using the terrestrial isopod crustacean Armadillidium vulgare, its highly diverse microbiota (>200 bacterial genera) and its three feminizing Wolbachia strains (wVulC, wVulM, wVulP) as a model system, the present study demonstrates that Wolbachia can even influence the composition of a diverse bacterial community under both laboratory and natural conditions. While host origin is the major determinant of the taxonomic composition of the microbiota in A. vulgare, Wolbachia infection affected both the presence and, more importantly, the abundance of many bacterial taxa within each host population, possibly due to competitive interactions. Moreover, different Wolbachia strains had different impacts on microbiota composition. As such, infection with wVulC affected a higher number of taxa than infection with wVulM, possibly due to intrinsic differences in virulence and titer between these two strains. In conclusion, this study shows that heritable endosymbionts such as Wolbachia can act as biotic factors shaping the microbiota of arthropods, with as yet unknown consequences on host fitness.

RevDate: 2018-06-03

Li H, Li T, J Qu (2018)

Stochastic processes govern bacterial communities from the blood of pikas and from their arthropod vectors.

FEMS microbiology ecology, 94(6):.

Vector-borne microbes influence pathogen transmission and blood microbiomes, thereby affecting the emergence of infectious diseases. Thus, understanding the relationship between host and vector microbiomes is of importance. In this study, we investigated the bacterial community composition, diversity and assembly of the flea (Rhadinopsylla dahurica vicina), torsalo (Hypoderma curzonial), and the blood and gut of their shared pika host, Ochotona curzoniae. Bartonella, Sphingomonas and Bradyrhizobium were enriched in blood, while Wolbachia and Fusobacterium were more abundant in fleas and torsaloes. Most of potential pathogenic microbes (belonging to Fusobacterium, Rickettsia, Kingella, Porphyromonas, Bartonella and Mycoplasma) were present in the blood of pikas and their vectors. Blood communities were more similar to those from fleas than other sample types and were independent of host factors or geographical sites. Notably, blood microbes originate mainly from fleas rather than gut or torsaloes. Interestingly, the community assembly of blood, fleas or torsaloes was primarily governed by stochastic processes, while the gut microbiome was determined by deterministic processes. Ecological drift plays a dominant role in the assembly of blood and flea microbiomes. These results reflect the difficulty for predicting and regulating the microbial ecology of fleas for the prevention of potential microbiome-associated diseases.

RevDate: 2018-05-11

Pereira TN, Rocha MN, Sucupira PHF, et al (2018)

Wolbachia significantly impacts the vector competence of Aedes aegypti for Mayaro virus.

Scientific reports, 8(1):6889 pii:10.1038/s41598-018-25236-8.

Wolbachia, an intracellular endosymbiont present in up to 70% of all insect species, has been suggested as a sustainable strategy for the control of arboviruses such as Dengue, Zika and Chikungunya. As Mayaro virus outbreaks have also been reported in Latin American countries, the objective of this study was to evaluate the vector competence of Brazilian field-collected Ae. aegypti and the impact of Wolbachia (wMel strain) upon this virus. Our in vitro studies with Aag2 cells showed that Mayaro virus can rapidly multiply, whereas in wMel-infected Aag2 cells, viral growth was significantly impaired. In addition, C6/36 cells seem to have alterations when infected by Mayaro virus. In vivo experiments showed that field-collected Ae. aegypti mosquitoes are highly permissive to Mayaro virus infection, and high viral prevalence was observed in the saliva. On the other hand, Wolbachia-harboring mosquitoes showed significantly impaired capability to transmit Mayaro virus. Our results suggest that the use of Wolbachia-harboring mosquitoes may represent an effective mechanism for the reduction of Mayaro virus transmission throughout Latin America.

RevDate: 2018-05-03

Pance A (2018)

Can Wolbachia save the day?.

RevDate: 2018-06-23

Steiner FM, Csősz S, Markó B, et al (2018)

Turning one into five: Integrative taxonomy uncovers complex evolution of cryptic species in the harvester ant Messor "structor".

Molecular phylogenetics and evolution pii:S1055-7903(17)30552-3 [Epub ahead of print].

Seed harvesting ants are ecosystem engineers that shape vegetation, nutrient cycles, and microclimate. Progress in ecological research is, however, slowed down by poor species delimitation. For example, it has not been resolved to date, how many species the European harvester ant Messor "structor" (Latreille, 1798) represents. Since its first description, splitting into additional taxa was often proposed but not accepted later on due to inconsistent support from morphology and ecology. Here, we took an iterative integrative-taxonomy approach - comparing multiple, independent data sets of the same sample - and used traditional morphometrics, Wolbachia symbionts, mitochondrial DNA, amplified fragment length polymorphism, and ecological niche modelling. Using the complementarity of the data sets applied, we resolved multiple, strong disagreements over the number of species, ranging from four to ten, and the allocation of individuals to species. We consider most plausible a five-species hypothesis and conclude the taxonomic odyssey by redescribing Messor structor, M. ibericus Santschi, 1925, and M. muticus (Nylander, 1849) stat.rev., and by describing two new species, M. ponticus sp.n. and M. mcarthuri sp.n. The evolutionary explanations invoked in resolving the various data conflicts include pronounced morphological crypsis, incomplete lineage-sorting or ongoing cospeciation of endosymbionts, and peripatric speciation - these ants' significance to evolutionary biology parallels that to ecology. The successful solution of this particular problem illustrates the usefulness of the integrative approach to other systematic problems of comparable complexity and the importance of understanding evolution to drawing correct conclusions on species' attributes, including their ecology and biogeography.

RevDate: 2018-07-09
CmpDate: 2018-07-09

Ote M, D Yamamoto (2018)

Enhancing Nanos expression via the bacterial TomO protein is a conserved strategy used by the symbiont Wolbachia to fuel germ stem cell maintenance in infected Drosophila females.

Archives of insect biochemistry and physiology, 98(3):e21471.

The toxic manipulator of oogenesis (TomO) protein has been identified in the wMel strain of Wolbachia that symbioses with the vinegar fly Drosophila melanogaster, as a protein that affects host reproduction. TomO protects germ stem cells (GSCs) from degeneration, which otherwise occurs in ovaries of host females that are mutant for the gene Sex-lethal (Sxl). We isolated the TomO homologs from wPip, a Wolbachia strain from the mosquito Culex quinquefasciatus. One of the homologs, TomOwPip 1, exerted the GSC rescue activity in fly Sxl mutants when lacking its hydrophobic stretches. The GSC-rescuing action of the TomOwPip 1 variant was ascribable to its abilities to associate with Nanos (nos) mRNA and to enhance Nos protein expression. The analysis of structure-activity relationships with TomO homologs and TomO deletion variants revealed distinct modules in the protein that are each dedicated to different functions, i.e., subcellular localization, nos mRNA binding or Nos expression enhancement. We propose that modular reshuffling is the basis for structural and functional diversification of TomO protein members.

RevDate: 2018-07-09

Bridgeman B, Morgan-Richards M, Wheeler D, et al (2018)

First detection of Wolbachia in the New Zealand biota.

PloS one, 13(4):e0195517 pii:PONE-D-17-28125.

Wolbachia is one of the most widespread intracellular bacteria on earth, estimated to infect between 40 and 66% of arthropod species in most ecosystems that have been surveyed. Their significance rests not only in their vast distribution, but also in their ability to modify the reproductive biology of their hosts, which can ultimately affect genetic diversity and speciation of infected populations. Wolbachia has yet to be formally identified in the fauna of New Zealand which has high levels of endemic biodiversity and this represents a gap in our understanding of the global biology of Wolbachia. Using High Throughput Sequencing (HTS) of host DNA in conjunction with traditional molecular techniques we identified six endemic Orthoptera species that were positive for Wolbachia infection. In addition, short-sequence amplification with Wolbachia specific primers applied to New Zealand and introduced invertebrates detected a further 153 individuals positive for Wolbachia. From these short-range DNA amplification products sequence data was obtained for the ftsZ gene region from 86 individuals representing 10 host species. Phylogenetic analysis using the sequences obtained in this study reveals that there are two distinct Wolbachia bacteria lineages in New Zealand hosts belonging to recognised Wolbachia supergroups (A and B). These represent the first described instances of Wolbachia in the New Zealand native fauna, including detection in putative parasitoids of infected Orthoptera suggesting a possible transmission path. Our detection of Wolbachia infections of New Zealand species provides the opportunity to study local transmission of Wolbachia and explore their role in the evolution of New Zealand invertebrates.

RevDate: 2018-05-31

Henry LP, ILG Newton (2018)

Mitochondria and Wolbachia titers are positively correlated during maternal transmission.

Molecular ecology, 27(11):2634-2646.

Mothers provide their offspring with symbionts. Maternally transmitted, intracellular symbionts must disperse from mother to offspring with other cytoplasmic elements, like mitochondria. Here, we investigated how the intracellular symbiont Wolbachia interacts with mitochondria during maternal transmission. Mitochondria and Wolbachia may interact antagonistically and compete as each population tries to ensure its own evolutionary success. Alternatively, mitochondria and Wolbachia may cooperate as both benefit from ensuring the fitness of the mother. We characterized the relationship between mitochondria and Wolbachia titers in ovaries of Drosophila melanogaster. We found that mitochondria and Wolbachia titers are positively correlated in common laboratory genotypes of D. melanogaster. We attempted to perturb this covariation through the introduction of Wolbachia variants that colonize at different titers. We also attempted to perturb the covariation through manipulating the female reproductive tract to disrupt maternal transmission. Finally, we also attempted to disrupt the covariation by knocking down gene expression for two loci involved in mitochondrial metabolism: NADH dehydrogenase and a mitochondrial transporter. Overall, we find that mitochondria and Wolbachia titers are commonly positively correlated, but this positive covariation is disrupted at high titers of Wolbachia. Our results suggest that mitochondria and Wolbachia have likely evolved mechanisms to stably coexist, but the competitive dynamics change at high Wolbachia titers. We provide future directions to better understand how their interaction influences the maintenance of the symbiosis.

RevDate: 2018-05-29
CmpDate: 2018-05-29

Foray V, Pérez-Jiménez MM, Fattouh N, et al (2018)

Wolbachia Control Stem Cell Behavior and Stimulate Germline Proliferation in Filarial Nematodes.

Developmental cell, 45(2):198-211.e3.

Although symbiotic interactions are ubiquitous in the living world, examples of developmental symbioses are still scarce. We show here the crucial role of Wolbachia in the oogenesis of filarial nematodes, a class of parasites of biomedical and veterinary relevance. We applied newly developed techniques to demonstrate the earliest requirements of Wolbachia in the parasite germline preceding the production of faulty embryos in Wolbachia-depleted nematodes. We show that Wolbachia stimulate germline proliferation in a cell-autonomous manner, and not through nucleotide supplementation as previously hypothesized. We also found Wolbachia to maintain the quiescence of a pool of germline stem cells to ensure a constant delivery of about 1,400 eggs per day for many years. The loss of quiescence upon Wolbachia depletion as well as the disorganization of the distal germline suggest that Wolbachia are required to execute the proper germline stem cell developmental program in order to produce viable eggs and embryos.

RevDate: 2018-04-26

Russell JE, Nunney L, Saum M, et al (2018)

Host and symbiont genetic contributions to fitness in a Trichogramma-Wolbachia symbiosis.

PeerJ, 6:e4655 pii:4655.

The fitness effects associated with Wolbachia infection have wide-ranging ecological and evolutionary consequences for host species. How these effects are modulated by the relative influence of host and Wolbachia genomes has been described as a balancing act of genomic cooperation and conflict. For vertically transmitted symbionts, like cytoplasmic Wolbachia, concordant host-symbiont fitness interests would seem to select for genomic cooperation. However, Wolbachia's ability to manipulate host reproductive systems and distort offspring sex ratios presents an evolutionary conflict of interest with infected hosts. In the parthenogenesis-inducing (PI) form of Wolbachia found in many haplodiploid insects, Wolbachia fitness is realized through females and is enhanced by their feminization of male embryos and subsequent parthenogenetic reproduction. In contrast, as long as Wolbachia is not fixed in a population and sexual reproduction persists, fitness for the host species is realized through both male and female offspring production. How these cooperating and competing interests interact and the relative influence of host and Wolbachia genomes were investigated in the egg parasitoid Trichogramma kaykai, where Wolbachia infection has remained at a low frequency in the field. A factorial design in which laboratory cultures of Wolbachia-infected T. kaykai were cured and re-infected with alternative Wolbachia strains was used to determine the relative influence of host and Wolbachia genomes on host fitness values. Our results suggest fitness variation is largely a function of host genetic background, except in the case of offspring sex ratio where a significant interaction between host and Wolbachia genomes was found. We also find a significant effect associated with the horizontal transfer of Wolbachia strains, which we discuss in terms of the potential for coadaptation in PI-Wolbachia symbioses.

RevDate: 2018-05-16

Shropshire JD, On J, Layton EM, et al (2018)

One prophage WO gene rescues cytoplasmic incompatibility in Drosophila melanogaster.

Proceedings of the National Academy of Sciences of the United States of America, 115(19):4987-4991.

Wolbachia are maternally inherited, intracellular bacteria at the forefront of vector control efforts to curb arbovirus transmission. In international field trials, the cytoplasmic incompatibility (CI) drive system of wMel Wolbachia is deployed to replace target vector populations, whereby a Wolbachia-induced modification of the sperm genome kills embryos. However, Wolbachia in the embryo rescue the sperm genome impairment, and therefore CI results in a strong fitness advantage for infected females that transmit the bacteria to offspring. The two genes responsible for the wMel-induced sperm modification of CI, cifA and cifB, were recently identified in the eukaryotic association module of prophage WO, but the genetic basis of rescue is unresolved. Here we use transgenic and cytological approaches to demonstrate that maternal cifA expression independently rescues CI and nullifies embryonic death caused by wMel Wolbachia in Drosophila melanogaster Discovery of cifA as the rescue gene and previously one of two CI induction genes establishes a "Two-by-One" model that underpins the genetic basis of CI. Results highlight the central role of prophage WO in shaping Wolbachia phenotypes that are significant to arthropod evolution and vector control.

RevDate: 2018-06-01

Monsanto-Hearne V, KN Johnson (2018)

Wolbachia-mediated protection of Drosophila melanogaster against systemic infection with its natural viral pathogen Drosophila C virus does not involve changes in levels of highly abundant miRNAs.

The Journal of general virology, 99(6):827-831.

The presence of Wolbachia confers virus protection to insects. The molecular mechanism underlying Wolbachia-mediated protection in this tripartite host-endosymbiont-virus interaction is not yet fully understood. In the bipartite association between Drosophila melanogaster and Drosophila C virus (DCV), changes in the expression of microRNAs (miRNAs) influence the outcome of viral pathogenesis. Here we examined whether changes in miRNA expression are similarly involved in the Drosophila-Wolbachia-DCV association. The levels of highly abundant miRNAs in D. melanogaster, Wolbachia-mono-infected D. melanogaster, and DCV- and Wolbachia-bi-infected D. melanogaster were quantified using RT-qPCR and compared. The results show that the abundance of the 17 tested D. melanogaster miRNAs is not affected by Wolbachia endosymbiosis or by bi-infection of Wolbachia and DCV. These results suggest that the in vivo protection conferred by Wolbachia to its native host against D. melanogaster's natural pathogen DCV is not likely to be dependent on or associated with changes in the levels of highly expressed miRNAs.

RevDate: 2018-04-22

Mally R, Huemer P, M Nuss (2018)

Deep intraspecific DNA barcode splits and hybridisation in the Udea alpinalis group (Insecta, Lepidoptera, Crambidae) - an integrative revision.

ZooKeys.

The analysis of mitochondrial COI data for the European-Centroasian montane Udea alpinalis species group finds deep intraspecific splits. Specimens of U. austriacalis and U. rhododendronalis separate into several biogeographical groups. These allopatric groups are not recovered in the analyses of the two nuclear markers wingless and Elongation factor 1-alpha, except for U. austriacalis from the Pyrenees and the French Massif Central. The latter populations are also morphologically distinct and conspecific with Scopula donzelalis Guenée, 1854, which is removed from synonymy and reinstated as Udea donzelalis (Guenée, 1854) stat. rev. Furthermore, Udea altaica (Zerny, 1914), stat. n. from the Mongolian central Altai mountains, U. juldusalis (Zerny, 1914), stat. n. from the Tian Shan mountains of Kazakhstan, Kyrgyzstan and NW China, and U. plumbalis (Zerny, 1914), stat. n. from the Sayan Mountains of Northern Mongolia are raised to species level, and lectotypes are designated. Evidence of introgression of U. alpinalis into U. uliginosalis at three localities in the Central Alps is presented. A screening for Wolbachia using the markers wsp, gatB and ftsZ was negative for the U. alpinalis species group, but Wolbachia was found in single specimens of U. fulvalis and U. olivalis (both in the U. numeralis species group). We do not find evidence for the conjecture of several authors of additional subspecies in U. rhododendronalis, and synonymise U. rhododendronalis luquetalis Leraut, 1996, syn. n. and U. r. ventosalis Leraut, 1996, syn. n. with the nominal U. rhododendronalis (Duponchel, 1834).

RevDate: 2018-04-22

Ahlers LRH, AG Goodman (2018)

The Immune Responses of the Animal Hosts of West Nile Virus: A Comparison of Insects, Birds, and Mammals.

Frontiers in cellular and infection microbiology, 8:96.

Vector-borne diseases, including arboviruses, pose a serious threat to public health worldwide. Arboviruses of the flavivirus genus, such as Zika virus (ZIKV), dengue virus, yellow fever virus (YFV), and West Nile virus (WNV), are transmitted to humans from insect vectors and can cause serious disease. In 2017, over 2,000 reported cases of WNV virus infection occurred in the United States, with two-thirds of cases classified as neuroinvasive. WNV transmission cycles through two different animal populations: birds and mosquitoes. Mammals, particularly humans and horses, can become infected through mosquito bites and represent dead-end hosts of WNV infection. Because WNV can infect diverse species, research on this arbovirus has investigated the host response in mosquitoes, birds, humans, and horses. With the growing geographical range of the WNV mosquito vector and increased human exposure, improved surveillance and treatment of the infection will enhance public health in areas where WNV is endemic. In this review, we survey the bionomics of mosquito species involved in Nearctic WNV transmission. Subsequently, we describe the known immune response pathways that counter WNV infection in insects, birds, and mammals, as well as the mechanisms known to curb viral infection. Moreover, we discuss the bacterium Wolbachia and its involvement in reducing flavivirus titer in insects. Finally, we highlight the similarities of the known immune pathways and identify potential targets for future studies aimed at improving antiviral therapeutic and vaccination design.

RevDate: 2018-04-22

King JG, Souto-Maior C, Sartori LM, et al (2018)

Variation in Wolbachia effects on Aedes mosquitoes as a determinant of invasiveness and vectorial capacity.

Nature communications, 9(1):1483 pii:10.1038/s41467-018-03981-8.

Wolbachia has been introduced into Aedes aegypti mosquitoes to control the spread of arboviruses, such as dengue, chikungunya and Zika. Studies showed that certain Wolbachia strains (such as wMel) reduce replication of dengue viruses in the laboratory, prompting the release of mosquitoes carrying the bacterium into the field, where vectorial capacity can be realistically assessed in relation to native non-carriers. Here we apply a new analysis to two published datasets, and show that wMel increases the mean and the variance in Ae. aegypti susceptibility to dengue infection when introgressed into Brazil and Vietnam genetic backgrounds. In the absence of other processes, higher mean susceptibility should lead to enhanced viral transmission. The increase in variance, however, widens the basis for selection imposed by unexplored natural forces, retaining the potential for reducing transmission overall.

RevDate: 2018-04-16

Kramer L, Crosara S, Gnudi G, et al (2018)

Wolbachia, doxycycline and macrocyclic lactones: New prospects in the treatment of canine heartworm disease.

Veterinary parasitology, 254:95-97.

Melarsomine dihydrochloride (Immiticide®, Merial) is the only approved adulticidal drug for the treatment of canine heartworm disease (HWD). However, in cases where arsenical therapy is not possible or is contraindicated, a monthly heartworm preventive along with doxycycline for a 4-week period, which targets the bacterial endosymbiont Wolbachia, might be considered. There are published reports on the efficacy of ivermectin and doxycycline in both experimentally and naturally infected dogs, but no data on the use of other macrocyclic lactones (MLs) with a similar treatment regime. Preliminary results of studies in dogs show that a topical formulation of moxidectin, the only ML currently registered as a microfilaricide, is also adulticidal when combined with doxycycline. It is not yet known if the efficacy of these combination therapies is due to pharmacokinetic synergism. A recent study showed that serum levels of doxycycline in dogs treated with the combination protocol were not statistically different compared to dogs treated with doxycycline alone. However, lungs from dogs treated with the combination therapy showed a marked reduction in T regulatory cells, indicating that treatment efficacy may be due to a heightened immune response against the parasite. Further studies are necessary to evaluate the long-term clinical outcome of combination protocols and to establish the most efficient treatment for HWD in dogs.

RevDate: 2018-04-14

Bonneau M, Atyame C, Beji M, et al (2018)

Author Correction: Culex pipiens crossing type diversity is governed by an amplified and polymorphic operon of Wolbachia.

Nature communications, 9(1):1491 pii:10.1038/s41467-018-03799-4.

In the originally published HTML and PDF versions of this Article, gel images in Figures 7c and 8c were not prepared as per the Nature journal policy. These figure panels have now been corrected in both the PDF and HTML versions of the Article.In Fig. 7c, the lane labelled 'Ha' was inappropriately duplicated to represent the lane labelled 'Ich13'. The corrected version of Fig. 7c includes PCR-RFLP on DNA from the Ichkeul 13 line, which had been run on a separate gel. The original unprocessed gel images are provided in Supplementary Figure 1 associated with this correction, with the relevant corresponding bands denoted. A repeat experiment of the PCR-RFLP test is also presented as Supplementary Figure 2.In Fig. 8c, the image was assembled from two separate gels without clear demarcation. The corrected Fig. 8c clearly separates lanes from the two gels, and the original unprocessed gel images are provided in the Supplementary Information associated with this correction.These corrections do not alter the original meaning of the experiments, their results, their interpretation, or the conclusions of the paper. We apologize for any confusion this may have caused to the readers of Nature Communications.

RevDate: 2018-06-20
CmpDate: 2018-06-19

Asad S, Hussain M, Hugo L, et al (2018)

Suppression of the pelo protein by Wolbachia and its effect on dengue virus in Aedes aegypti.

PLoS neglected tropical diseases, 12(4):e0006405 pii:PNTD-D-17-00001.

The endosymbiont Wolbachia is known to block replication of several important arboviruses, including dengue virus (DENV), in the mosquito vector Aedes aegypti. So far, the exact mechanism of this viral inhibition is not fully understood. A recent study in Drosophila melanogaster has demonstrated an interaction between the pelo gene and Drosophila C virus. In this study, we explored the possible involvement of the pelo protein, that is involved in protein translation, in Wolbachia-mediated antiviral response and mosquito-DENV interaction. We found that pelo is upregulated during DENV replication and its silencing leads to reduced DENV virion production suggesting that it facilities DENV replication. However, in the presence of Wolbachia, specifically in female mosquitoes, the pelo protein is downregulated and its subcellular localization is altered, which could contribute to reduction in DENV replication in Ae. aegypti. In addition, we show that the microRNA aae-miR-2940-5p, whose abundance is highly enriched in Wolbachia-infected mosquitoes, might mediate regulation of pelo. Our data reveals identification of pelo as a host factor that is positively involved in DENV replication, and its suppression in the presence of Wolbachia may contribute to virus blocking exhibited by the endosymbiont.

RevDate: 2018-04-12

Paniagua Voirol LR, Frago E, Kaltenpoth M, et al (2018)

Bacterial Symbionts in Lepidoptera: Their Diversity, Transmission, and Impact on the Host.

Frontiers in microbiology, 9:556.

The insect's microbiota is well acknowledged as a "hidden" player influencing essential insect traits. The gut microbiome of butterflies and moths (Lepidoptera) has been shown to be highly variable between and within species, resulting in a controversy on the functional relevance of gut microbes in this insect order. Here, we aim to (i) review current knowledge on the composition of gut microbial communities across Lepidoptera and (ii) elucidate the drivers of the variability in the lepidopteran gut microbiome and provide an overview on (iii) routes of transfer and (iv) the putative functions of microbes in Lepidoptera. To find out whether Lepidopterans possess a core gut microbiome, we compared studies of the microbiome from 30 lepidopteran species. Gut bacteria of the Enterobacteriaceae, Bacillaceae, and Pseudomonadaceae families were the most widespread across species, with Pseudomonas, Bacillus, Staphylococcus, Enterobacter, and Enterococcus being the most common genera. Several studies indicate that habitat, food plant, and age of the host insect can greatly impact the gut microbiome, which contributes to digestion, detoxification, or defense against natural enemies. We mainly focus on the gut microbiome, but we also include some examples of intracellular endosymbionts. These symbionts are present across a broad range of insect taxa and are known to exert different effects on their host, mostly including nutrition and reproductive manipulation. Only two intracellular bacteria genera (Wolbachia and Spiroplasma) have been reported to colonize reproductive tissues of Lepidoptera, affecting their host's reproduction. We explore routes of transmission of both gut microbiota and intracellular symbionts and have found that these microbes may be horizontally transmitted through the host plant, but also vertically via the egg stage. More detailed knowledge about the functions and plasticity of the microbiome in Lepidoptera may provide novel leads for the control of lepidopteran pest species.

RevDate: 2018-07-10

Pike A, G Dimopoulos (2018)

Genetic modification of Anopheles stephensi for resistance to multiple Plasmodium falciparum strains does not influence susceptibility to o'nyong'nyong virus or insecticides, or Wolbachia-mediated resistance to the malaria parasite.

PloS one, 13(4):e0195720 pii:PONE-D-17-41891.

Mosquitoes that have been genetically engineered for resistance to human pathogens are a potential new tool for controlling vector-borne disease. However, genetic modification may have unintended off-target effects that could affect the mosquitoes' utility for disease control. We measured the resistance of five genetically modified Plasmodium-suppressing Anopheles stephensi lines to o'nyong'nyong virus, four classes of insecticides, and diverse Plasmodium falciparum field isolates and characterized the interactions between our genetic modifications and infection with the bacterium Wolbachia. The genetic modifications did not alter the mosquitoes' resistance to either o'nyong'nyong virus or insecticides, and the mosquitoes were equally resistant to all tested P. falciparum strains, regardless of Wolbachia infection status. These results indicate that mosquitoes can be genetically modified for resistance to malaria parasite infection and remain compatible with other vector-control measures without becoming better vectors for other pathogens.

RevDate: 2018-04-28

Li Y, X Liu (2018)

A sex-structured model with birth pulse and release strategy for the spread of Wolbachia in mosquito population.

Journal of theoretical biology, 448:53-65.

Dengue fever is one of the most important diseases causing illness and death all over the world, which brings tremendous threat to peoples' life and property security, especially in the undeveloped areas. The main vector, Aedes aegypti, must be controlled to prevent the transmission of dengue. There are a variety of methods to control it. Wolbachia is an innovative bacterium which breaks the dengue transmission cycle for its characteristics of cytoplasmic incompatibility and maternal transmission. In this paper, a sex-structured model with birth pulse is established to study the spread of Wolbachia in mosquito population. The results show that if the maternal transmission is perfect, Wolbachia will spread successfully. Moreover, all the mosquitoes will be infected with Wolbachia. If the maternal transmission is imperfect, there are two locally asymptotically stable periodic solutions. One is Wolbachia-extinction periodic solution, and the other is part replacement periodic solution. Numerical simulations show that the initial occupancy of Wolbachia-infected mosquitoes has an important effect on the success of part replacement strategy. If the initial occupancy is relatively large, the part replacement strategy can be successful. Furthermore, in consideration of the fact that the initial occupancy cannot be always large enough in the wild nature, to release Wolbachia-infected mosquitoes artificially into the wild nature becomes necessary. Therefore, we add a release strategy into the sex-structured model with birth pulse for further analysis. The condition to ensure the stability of the Wolbachia total replacement periodic solution is obtained. Finally, the effect of the release quantity is simulated numerically.

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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 @ gmail.com

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).

Timelines

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

Biographies

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 )