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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 06 Dec 2019 at 01:53 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: 2019-12-05

Liu Y, Fan ZY, Xuan-An , et al (2019)

A single-pair method to screen Rickettsia-infected and uninfected whitefly Bemisia tabaci populations.

Journal of microbiological methods pii:S0167-7012(19)30781-X [Epub ahead of print].

Bacterial endosymbionts such as Rickettsia and Wolbachia play prominent roles in the development and behaviour of their insect hosts, such as whiteflies, aphids, psyllids and mealybugs. Accumulating studies have emphasized the importance of establishing experimental insect populations that are either lacking or bearing certain species of endosymbionts, because they are the basis in which to reveal the biological role of individual symbionts. In this study, using Rickettsia as an example, we explored a "single-pair screening" method to establish Rickettsia infected and uninfected populations of whitefly Bemisia tabaci MEAM1 for further experimental use. The original host population had a relatively low infection rate of Rickettsia (< 35%). When B. tabaci adults newly emerged, unmated males and females were randomly selected, and released into a leaf cage that covered a healthy plant leaf in order to oviposit F1 generation eggs. Following 6 days of oviposition, the parents were recaptured and used for PCR detection. The F1 progeny, for which parents were either Rickettsia positive or negative, were used to produce the F2 generation, and similarly in turn for the F3, F4 and F5 generations respectively; if the infection status of Rickettsia was consistent in the F1 to F5 generations, then the populations can be used as Rickettsia positive or negative lines for further experiments. In addition, our phylogenetic analyses revealed that Rickettsia has high fidelity during the maternal transmission in different generations.

RevDate: 2019-12-05

Wanji S, Nji TM, Hamill L, et al (2019)

Implementation of test-and-treat with doxycycline and temephos ground larviciding as alternative strategies for accelerating onchocerciasis elimination in an area of loiasis co-endemicity: the COUNTDOWN consortium multi-disciplinary study protocol.

Parasites & vectors, 12(1):574 pii:10.1186/s13071-019-3826-8.

BACKGROUND: Onchocerciasis is a priority neglected tropical disease targeted for elimination by 2025. The standard strategy to combat onchocerciasis is annual Community-Directed Treatment with ivermectin (CDTi). Yet, high prevalence rates and transmission persist following > 12 rounds in South-West Cameroon. Challenges include programme coverage, adherence to, and acceptability of ivermectin in an area of Loa loa co-endemicity. Loiasis patients harbouring heavy infections are at risk of potentially fatal serious adverse events following CDTi. Alternative strategies are therefore needed to achieve onchocerciasis elimination where CDTi effectiveness is suboptimal.

METHODS/DESIGN: We designed an implementation study to evaluate integrating World Health Organisation-endorsed alternative strategies for the elimination of onchocerciasis, namely test-and-treat with the macrofilaricide, doxycycline (TTd), and ground larviciding for suppression of blackfly vectors with the organophosphate temephos. A community-based controlled before-after intervention study will be conducted among > 2000 participants in 20 intervention (Meme River Basin) and 10 control (Indian River Basin) communities. The primary outcome measure is O. volvulus prevalence at follow-up 18-months post-treatment. The study involves four inter-disciplinary components: parasitology, entomology, applied social sciences and health economics. Onchocerciasis skin infection will be diagnosed by skin biopsy and Loa loa infection will be diagnosed by parasitological examination of finger-prick blood samples. A simultaneous clinical skin disease assessment will be made. Eligible skin-snip-positive individuals will be offered directly-observed treatment for 5 weeks with 100 mg/day doxycycline. Transmission assessments of onchocerciasis in the communities will be collected post-human landing catch of the local biting blackfly vector prior to ground larviciding with temephos every week (0.3 l/m3) until biting rate falls below 5/person/day. Qualitative research, including in-depth interviews and focus-group discussions will be used to assess acceptability and feasibility of the implemented alternative strategies among intervention recipients and providers. Health economics will assess the cost-effectiveness of the implemented interventions.

CONCLUSIONS: Using a multidisciplinary approach, we aim to assess the effectiveness of TTd, alone or in combination with ground larviciding, following a single intervention round and scrutinise the acceptability and feasibility of implementing at scale in similar hotspots of onchocerciasis infection, to accelerate onchocerciasis elimination.

RevDate: 2019-12-04

Staunton KM, Rohde BB, Townsend M, et al (2019)

Investigating Male Aedes aegypti (Diptera: Culicidae) Attraction to Different Oviposition Containers Using Various Configurations of the Sound Gravid Aedes Trap.

Journal of medical entomology pii:5651346 [Epub ahead of print].

Aedes aegypti (Linnaeus), the primary vectors of the arboviruses dengue virus and Zika virus, continue to expand their global distributions. In efforts to better control such species, several mosquito control programs are investigating the efficacy of rearing and releasing millions of altered male Aedes throughout landscapes to reduce populations and disease transmission risk. Unfortunately, little is known about Ae. aegypti, especially male, dispersal behaviors within urban habitats. We deployed Sound-producing Gravid Aedes Traps (SGATs) in Cairns, northern Australia, to investigate male Ae. aegypti attraction to various oviposition container configurations. The traps were arranged to include: 1) water only, 2) organically infused water, 3) infused water and L3 larvae, 4) infused water and a human-scented lure, and lastly 5) no water or olfactory attractant (dry). Our data suggest that males were more attracted to SGATs representing active larval sites than potential larval sites, but were equally attracted to dry SGATs relative to those containing water and/or infusion. Additionally, we found that female Ae. aegypti were equally attracted to wet SGATs, with or without infusion, but not dry ones. These results suggest that male Ae. aegypti within northern Australia are more attracted to active larval sites and equally attracted to dry containers as wet or infused ones. Additionally, female Ae. aegypti are unlikely to enter dry containers. Such findings contribute to our understanding of potentially attractive features for local and released Ae. aegypti throughout the northern Australian urban landscape.

RevDate: 2019-12-04

Devescovi F, Conte CA, Augustinos A, et al (2019)

Symbionts do not affect the mating incompatibility between the Brazilian-1 and Peruvian morphotypes of the Anastrepha fraterculus cryptic species complex.

Scientific reports, 9(1):18319 pii:10.1038/s41598-019-54704-y.

The South American fruit fly, Anastrepha fraterculus, is clearly undergoing a speciation process. Among others, two of their morphotypes, the Brazilian-1 and Peruvian, have accumulated differences in pre- and post-zygotic mechanisms resulting in a degree of reproductive isolation. Both harbor a different strain of Wolbachia, which is a widespread endosymbiotic bacterium among many invertebrates producing a range of reproductive effects. In this paper, we studied the role of this bacterium as one of the factors involved in such isolation process. Infected and cured laboratory colonies were used to test pre- and post-zygotic effects, with special emphasis in uni- and bi-directional cytoplasmic incompatibility (CI). We showed that Wolbachia is the only known reproductive symbiont present in these morphotypes. Wolbachia reduced the ability for embryonic development in crosses involving cured females and infected males within each morphotype (uni-directional CI). This inhibition showed to be more effective in the Peruvian morphotype. Bi-directional CI was not evidenced, suggesting the presence of compatible Wolbachia strains. We conclude that Wolbachia is not directly involved in the speciation process of these morphotypes. Other mechanisms rather than CI should be explored in order to explain the reduced mating compatibility between the Brazilian-1 and Peruvian morphotypes.

RevDate: 2019-12-04

Chung M, Teigen LE, Libro S, et al (2019)

Drug Repurposing of Bromodomain Inhibitors as Potential Novel Therapeutic Leads for Lymphatic Filariasis Guided by Multispecies Transcriptomics.

mSystems, 4(6): pii:4/6/e00596-19.

To better understand the transcriptomic interplay of organisms associated with lymphatic filariasis, we conducted multispecies transcriptome sequencing (RNA-Seq) on the filarial nematode Brugia malayi, its Wolbachia endosymbiont wBm, and its laboratory vector Aedes aegypti across the entire B. malayi life cycle. In wBm, transcription of the noncoding 6S RNA suggests that it may be a regulator of bacterial cell growth, as its transcript levels correlate with bacterial replication rates. For A. aegypti, the transcriptional response reflects the stress that B. malayi infection exerts on the mosquito with indicators of increased energy demand. In B. malayi, expression modules associated with adult female samples consistently contained an overrepresentation of genes involved in chromatin remodeling, such as the bromodomain-containing proteins. All bromodomain-containing proteins encoded by B. malayi were observed to be upregulated in the adult female, embryo, and microfilaria life stages, including 2 members of the bromodomain and extraterminal (BET) protein family. The BET inhibitor JQ1(+), originally developed as a cancer therapeutic, caused lethality of adult worms in vitro, suggesting that it may be a potential therapeutic that can be repurposed for treating lymphatic filariasis.IMPORTANCE The current treatment regimen for lymphatic filariasis is mostly microfilaricidal. In an effort to identify new drug candidates for lymphatic filariasis, we conducted a three-way transcriptomics/systems biology study of one of the causative agents of lymphatic filariasis, Brugia malayi, its Wolbachia endosymbiont wBm, and its vector host Aedes aegypti at 16 distinct B. malayi life stages. B. malayi upregulates the expression of bromodomain-containing proteins in the adult female, embryo, and microfilaria stages. In vitro, we find that the existing cancer therapeutic JQ1(+), which is a bromodomain and extraterminal protein inhibitor, has adulticidal activity in B. malayi.

RevDate: 2019-12-03

Fontes-Sousa AP, Silvestre-Ferreira AC, Carretón E, et al (2019)

Exposure of humans to the zoonotic nematode Dirofilaria immitis in Northern Portugal.

Epidemiology and infection, 147:e282 pii:S0950268819001687.

Dirofilariosis caused by Dirofilaria immitis (heartworm) is a zoonosis, considered an endemic disease of dogs and cats in several countries of Western Europe, including Portugal. This study assesses the levels of D. immitis exposure in humans from Northern Portugal, to which end, 668 inhabitants of several districts belonging to two different climate areas (Csa: Bragança, Vila Real and Csb: Aveiro, Braga, Porto, Viseu) were tested for anti-D. immitis and anti-Wolbachia surface proteins (WSP) antibodies. The overall prevalence of seropositivity to both anti-D. immitis and WSP antibodies was 6.1%, which demonstrated the risk of infection with D. immitis in humans living in Northern Portugal. This study, carried out in a Western European country, contributes to the characterisation of the risk of infection with D. immitis among human population in this region of the continent. From a One Health point of view, the results of the current work also support the close relationship between dogs and people as a risk factor for human infection.

RevDate: 2019-12-03

Zhou JC, Li YY, Liu QQ, et al (2019)

Effects of temperature and superparasitism on quality and characteristics of thelytokous Wolbachia-infected Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) during mass rearing.

Scientific reports, 9(1):18114 pii:10.1038/s41598-019-54719-5.

Thelytokous Wolbachia-infected Trichogramma spp. are widely used egg parasitoids against lepidopteran pests in biological control programs. Wolbachia may manipulate host wasps for superparasitism and is sensitive to temperature. To explore effects of temperature and superparasitism, we compared fitness parameters and Wolbachia-mediated phenotype of thelytokous Wolbachia-infected Trichogramma dendrolimi between those emerging from superparasitised or single-parasitised hosts at 17, 21, 25, or 29 °C. Infected mothers of T. dendrolimi showed reduced superparasitism and parasitism increased with temperature. Wolbachia titre decreased with temperature when females emerged from singly-parasitised hosts, but there was no correlation in superparasitised hosts. Females showed higher Wolbachia titres at 21, 25, or 29 °C when developing from superparasitised hosts. The daily male ratio of offspring increased with temperature, and the day-age threshold for 5%, 50%, or 95% daily male ratio decreased with temperature in both parasitism forms. Females that emerged from superparasitised hosts had a shorter life span and reduced fecundity. These results indicate that Wolbachia may affect host behaviour by increasing superparasitism to enhance its spread, but this has negative effects on thelytokous Wolbachia-infected T. dendrolimi.

RevDate: 2019-12-01

Hotterbeekx A, Raimon S, Abd-Elfarag G, et al (2019)

Onchocerca volvulus is not detected in the cerebrospinal fluid of persons with onchocerciasis-associated epilepsy.

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases pii:S1201-9712(19)30469-2 [Epub ahead of print].

OBJECTIVES: Epidemiological evidence links onchocerciasis with the development of epilepsy. We aimed to detectOnchocerca volvulus microfilariae or its bacterial endosymbiont, Wolbachia, in the cerebrospinal fluid (CSF) of persons with onchocerciasis-associated epilepsy (OAE).

METHODS: Thirteen persons with OAE andO. volvulus skin snip densities of >80 microfilatiae were recruited in Maridi County (South Sudan), and their CSF obtained. Cytospin centrifuged preparations of CSF were examined by light microscopy for presence of O. volvulus microfilariae. DNA was extracted from CSF to detect O. volvulus (O-150 repeat) by quantitative real-time PCR, and Wolbachia (FtsZ gene) by standard PCR. To further investigate if CSF from onchocerciasis-infected participants could induce seizures, 3- and 7-days old zebrafish larvae were injected with the CSF intracardially and intraperitoneally, respectively. For other zebrafish larvae, CSF was added directly to the larval medium.

RESULTS: No microfilariae, parasite orWolbachia DNA were detected in any of the CSF samples by light microscopy or PCR, respectively. All zebrafish survived the procedures and none developed seizures.

CONCLUSION: The absence of O. volvulus in CSF suggests that OAE is likely not caused by direct parasite invasion into the central nervous system, but by another phenomenon triggered by O. volvulus infection.

RevDate: 2019-11-30

Ullah MS, Kamimura T, T Gotoh (2019)

Effects of Temperature on Demographic Parameters of Bryobia praetiosa (Acari: Tetranychidae).

Journal of economic entomology pii:5648928 [Epub ahead of print].

The clover mite, Bryobia praetiosa Koch (Acari: Tetranychidae), is an agricultural pest, as well as a frequent invader of hospitals and homes. However, its adaptability to different temperatures is not well understood. We used age- and stage-specific life tables to investigate the effects of temperature on demographic parameters of B. praetiosa from 15 to 35°C under a long-day photoperiod (16:8 [L:D] h). The clover mite is a thelytokous species (consisting of only females) due to its infection with the symbiotic bacterium Wolbachia. The egg-to-adult development time of female B. praetiosa decreased as the temperature increased from 15 to 32.5°C. At 35°C, females laid eggs, but no eggs hatched. The lower thermal threshold (t0) and the thermal constant (K) for egg-to-adult females were 8.7°C and 274.1 degree-days, respectively. The intrinsic optimum temperature (TØ) was 22.4°C. The oviposition period decreased with increasing temperature. Fecundity was highest at 20°C and extremely low at 30°C. The net reproductive rate (R0) decreased as the temperature increased from 15 to 30°C, but no significant difference was observed between 15 and 20°C. The intrinsic rate of natural increase (r) varied from 0.0721/d at 15°C to 0.1679/d at 25°C, and then decreased to 0.1203/d at 30°C. These results should be useful in developing management strategies for B. praetiosa.

RevDate: 2019-11-29

Vivero RJ, Villegas-Plazas M, Cadavid-Restrepo GE, et al (2019)

Wild specimens of sand fly phlebotomine Lutzomyia evansi, vector of leishmaniasis, show high abundance of Methylobacterium and natural carriage of Wolbachia and Cardinium types in the midgut microbiome.

Scientific reports, 9(1):17746 pii:10.1038/s41598-019-53769-z.

Phlebotomine sand flies are remarkable vectors of several etiologic agents (virus, bacterial, trypanosomatid Leishmania), posing a heavy health burden for human populations mainly located at developing countries. Their intestinal microbiota is involved in a wide range of biological and physiological processes, and could exclude or facilitate such transmission of pathogens. In this study, we investigated the Eubacterial microbiome from digestive tracts of Lu. evansi adults structure using 16S rRNA gene sequence amplicon high throughput sequencing (Illumina MiSeq) obtained from digestive tracts of Lu. evansi adults. The samples were collected at two locations with high incidence of the disease in humans: peri-urban and forest ecosystems from the department of Sucre, Colombia. 289,068 quality-filtered reads of V4 region of 16S rRNA gene were obtained and clustered into 1,762 operational taxonomic units (OTUs) with 97% similarity. Regarding eubacterial diversity, 14 bacterial phyla and 2 new candidate phyla were found to be consistently associated with the gut microbiome content. Proteobacteria, Firmicutes, and Bacteroidetes were the most abundant phyla in all the samples and the core microbiome was particularly dominated by Methylobacterium genus. Methylobacterium species, are known to have mutualistic relationships with some plants and are involved in shaping the microbial community in the phyllosphere. As a remarkable feature, OTUs classified as Wolbachia spp. were found abundant on peri-urban ecosystem samples, in adult male (OTUs n = 776) and unfed female (OTUs n = 324). Furthermore, our results provide evidence of OTUs classified as Cardinium endosymbiont in relative abundance, notably higher with respect to Wolbachia. The variation in insect gut microbiota may be determined by the environment as also for the type of feeding. Our findings increase the richness of the microbiota associated with Lu. evansi. In this study, OTUs of Methylobacterium found in Lu. evansi was higher in engorged females, suggesting that there are interactions between microbes from plant sources, blood nutrients and the parasites they transmit during the blood intake.

RevDate: 2019-11-28

Stouthamer CM, Kelly SE, Mann E, et al (2019)

Development of a multi-locus sequence typing system helps reveal the evolution of Cardinium hertigii, a reproductive manipulator symbiont of insects.

BMC microbiology, 19(1):266 pii:10.1186/s12866-019-1638-9.

BACKGROUND: Cardinium is an intracellular bacterial symbiont in the phylum Bacteroidetes that is found in many different species of arthropods and some nematodes. This symbiont is known to be able to induce three reproductive manipulation phenotypes, including cytoplasmic incompatibility. Placing individual strains of Cardinium within a larger evolutionary context has been challenging because only two, relatively slowly evolving genes, 16S rRNA gene and Gyrase B, have been used to generate phylogenetic trees, and consequently, the relationship of different strains has been elucidated in only its roughest form.

RESULTS: We developed a Multi Locus Sequence Typing (MLST) system that provides researchers with three new genes in addition to Gyrase B for inferring phylogenies and delineating Cardinium strains. From our Cardinium phylogeny, we confirmed the presence of a new group D, a Cardinium clade that resides in the arachnid order harvestmen (Opiliones). Many Cardinium clades appear to display a high degree of host affinity, while some show evidence of host shifts to phylogenetically distant hosts, likely associated with ecological opportunity. Like the unrelated reproductive manipulator Wolbachia, the Cardinium phylogeny also shows no clear phylogenetic signal associated with particular reproductive manipulations.

CONCLUSIONS: The Cardinium phylogeny shows evidence of diversification within particular host lineages, and also of host shifts among trophic levels within parasitoid-host communities. Like Wolbachia, the relatedness of Cardinium strains does not necessarily predict their reproductive phenotypes. Lastly, the genetic tools proposed in this study may help future authors to characterize new strains and add to our understanding of Cardinium evolution.

RevDate: 2019-11-27

Beckmann JF, Sharma GD, Mendez L, et al (2019)

The Wolbachia cytoplasmic incompatibility enzyme CidB targets nuclear import and protamine-histone exchange factors.

eLife, 8: pii:50026.

Intracellular Wolbachia bacteria manipulate arthropod reproduction to promote their own inheritance. The most prevalent mechanism, cytoplasmic incompatibility (CI), traces to a Wolbachia deubiquitylase, CidB, and CidA. CidB has properties of a toxin, while CidA binds CidB and rescues embryonic viability. CidB is also toxic to yeast where we identified both host effects and high-copy suppressors of toxicity. The strongest suppressor was karyopherin-α, a nuclear-import receptor; this required nuclear localization-signal binding. A protein-interaction screen of Drosophila extracts using a substrate-trapping catalytic mutant, CidB*, also identified karyopherin-α; the P32 protamine-histone exchange factor bound as well. When CidB* bound CidA, these host protein interactions disappeared. These associations would place CidB at the zygotic male pronucleus where CI defects first manifest. Overexpression of karyopherin-α, P32, or CidA in female flies suppressed CI. We propose that CidB targets nuclear-protein import and protamine-histone exchange and that CidA rescues embryos by restricting CidB access to its targets.

RevDate: 2019-11-26

Lau MJ, Endersby-Harshman NM, Axford JK, et al (2019)

Measuring the Host-Seeking Ability of Aedes aegypti Destined for Field Release.

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

Host seeking is an essential process in mosquito reproduction. Field releases of modified mosquitoes for population replacement rely on successful host seeking by female mosquitoes, but host-seeking ability is rarely tested in a realistic context. We tested the host-seeking ability of female Aedes aegypti mosquitoes using a semi-field system. Females with different Wolbachia infection types (wMel-, wAlbB-infected, and uninfected) or from different origins (laboratory and field) were released at one end of a semi-field cage and recaptured as they landed on human experimenters 15 m away. Mosquitoes from each population were then identified with molecular tools or through minimal dusting with fluorescent powder. Wolbachia-infected and uninfected populations had similar average durations to landing and overall recapture proportions, as did laboratory and field-sourced Ae. aegypti. These results indicate that the host-seeking ability of mosquitoes is not negatively affected by Wolbachia infection or long-term laboratory maintenance. This method provides an approach to study the host-seeking ability of mosquitoes in a realistic setting, which will be useful when evaluating strains of mosquitoes that are planned for releases into the field to suppress arbovirus transmission.

RevDate: 2019-11-26

Ju JF, Bing XL, Zhao DS, et al (2019)

Wolbachia supplement biotin and riboflavin to enhance reproduction in planthoppers.

The ISME journal pii:10.1038/s41396-019-0559-9 [Epub ahead of print].

Symbiont-mediated nutritional mutualisms can contribute to the host fitness of insects, especially for those that feed exclusively on nutritionally unbalanced diets. Here, we elucidate the importance of B group vitamins in the association of endosymbiotic bacteria Wolbachia with two plant-sap feeding insects, the small brown planthopper, Laodelphax striatellus (Fallén), and the brown planthopper, Nilaparvata lugens (Stål). Infected planthoppers of both species laid more eggs than uninfected planthoppers, while the experimental transfer of Wolbachia into uninfected lines of one planthopper species rescued this fecundity deficit. The genomic analysis showed that Wolbachia strains from the two planthopper species encoded complete biosynthesis operons for biotin and riboflavin, while a metabolic analysis revealed that Wolbachia-infected planthoppers of both species had higher titers of biotin and riboflavin. Furthermore, experimental supplementation of food with a mixture of biotin and riboflavin recovered the fecundity deficit of Wolbachia-uninfected planthoppers. In addition, comparative genomic analysis suggested that the riboflavin synthesis genes are conserved among Wolbachia supergroups. Biotin operons are rare in Wolbachia, and those described share a recent ancestor that may have been horizontally transferred from Cardinium bacteria. Our research demonstrates a type of mutualism that involves a facultative interaction between Wolbachia and plant-sap feeding insects involving vitamin Bs.

RevDate: 2019-11-26

Liu QQ, Zhou JC, Zhang C, et al (2019)

Co-occurrence of thelytokous and bisexual Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) in a natural population.

Scientific reports, 9(1):17480 pii:10.1038/s41598-019-53992-8.

Trichogramma dendrolimi is one of the most successful biocontrol agents in China. However, an inundative condition is necessary to obtain acceptable parasitism effect. A good solution to this is the application of its thelytokous counterparts which unfortunately are scarce in field. We here report the first case of a natural T. dendrolimi population in China comprising both bisexual wasps and an extremely low proportion of thelytokous wasps. These two forms of T. dendrolimi are phylogenetically related based on the reconstructions of ITS-2 and COI genes. Also, the phylogenetic results suggested a potentially Wolbachia-drived ITS-2 variation. The expression of thelytoky was hardly affected by temperature, which might help control Asian corn borer and Dendrolimus punctatus. Wolbachia are responsible for current thelytoky according to phylogenetic analyses, antibiotic treatment and introgression experiment. We also present the third case of paternal sex ratio chromosome that restrains the expansion of Wolbachia. Moreover, the low frequency of thelytoky may be common in natural populations. Consequently if for biological control it is determined that a thelytokous strain is to be preferred, then large number of field collected females should be set up as isofemale lines, to detect the rare thelytoky.

RevDate: 2019-11-25

Lucchetti C, Genchi M, Venco L, et al (2019)

Optimized protocol for DNA/RNA co-extraction from adults of Dirofilaria immitis.

MethodsX, 6:2601-2605 pii:S2215-0161(19)30288-2.

Dirofilaria immitis, the etiologic agent of canine heartworm disease, like several other filarial nematodes, harbors the bacterial endosymbiont Wolbachia. To investigate metabolic and functional pathways of D. immitis and Wolbachia individually, along with their interactions, the use of both transcriptomic and genome analysis has becoming increasingly popular. Although several commercial kits are available for the single extraction of either DNA or RNA, no specific protocol has been described for simultaneous extraction of DNA and RNA from such a large organism like an adult D. immitis, where female worms generally reach ∼25 cm in length. More importantly, adult worms of D. immitis can only be obtained either through necropsy of experimentally infected dogs or by minimally-invasive surgical heartworm removal of naturally infected dogs. This makes each individual worm sample extremely important. Thus, in the context of a project aimed at the evaluation of both gene expression analysis and Wolbachia population assessment following different treatments, an optimized protocol for co-extraction of DNA and RNA from a single sample of adult D. immitis has been developed. •An optimized method for DNA/RNA co-extraction from large size nematodes using TRIzol® reagent.•Allows maximum exploitation of unique samples as adults of D. immitis.

RevDate: 2019-11-25

Nazni WA, Hoffmann AA, NoorAfizah A, et al (2019)

Establishment of Wolbachia Strain wAlbB in Malaysian Populations of Aedes aegypti for Dengue Control.

Current biology : CB pii:S0960-9822(19)31446-0 [Epub ahead of print].

Dengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however, the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.

RevDate: 2019-11-21

López-Madrigal S, EH Duarte (2019)

Titer regulation in arthropod-Wolbachia symbioses.

FEMS microbiology letters pii:5637388 [Epub ahead of print].

Symbiosis between intracellular bacteria (endosymbionts) and animals are widespread. The alphaproteobacterium Wolbachia pipientis is known to maintain a variety of symbiotic associations, ranging from mutualism to parasitism, with a wide range of invertebrates. Wolbachia infection might deeply affect host fitness (e.g. reproductive manipulation, antiviral protection), which is thought to explain its high prevalence in nature. Bacterial loads significantly influence both the infection dynamics and the extent of bacteria-induced host phenotypes. Hence, fine regulation of bacterial titers is considered as a milestone in host-endosymbiont interplay. Here we review both environmental and biological factors modulating Wolbachia titers in arthropods.

RevDate: 2019-11-20

Jasper ME, Yang Q, Ross PA, et al (2019)

A LAMP assay for the rapid and robust assessment of Wolbachia infection in Aedes aegypti under field and laboratory conditions.

PloS one, 14(11):e0225321 pii:PONE-D-19-23307.

With Wolbachia-based arbovirus control programs being scaled and operationalised around the world, cost effective and reliable detection of Wolbachia in field samples and laboratory stocks is essential for quality control. Here we validate a modified loop-mediated isothermal amplification (LAMP) assay for routine scoring of Wolbachia in mosquitoes from laboratory cultures and the field, applicable to any setting. We show that this assay is a rapid and robust method for highly sensitive and specific detection of wAlbB Wolbachia infection within Aedes aegypti under a variety of conditions. We test the quantitative nature of the assay by evaluating pooled mixtures of Wolbachia-infected and uninfected mosquitoes and show that it is capable of estimating infection frequencies, potentially circumventing the need to perform large-scale individual analysis for wAlbB infection status in the course of field monitoring. These results indicate that LAMP assays are useful for routine screening particularly under field conditions away from laboratory facilities.

RevDate: 2019-11-18

Zhao C, Zhao H, Zhang S, et al (2019)

The Developmental Stage Symbionts of the Pea Aphid-Feeding Chrysoperla sinica (Tjeder).

Frontiers in microbiology, 10:2454.

Chrysoperla sinica (Tjeder) is widely recognized as an important holometabolous natural enemy of various insect pests in different cropping systems and as a non-target surrogate in environmental risk assessment of Bt rice (i.e., genetically modified rice to express a toxin gene from Bacillus thuringiensis). Like other complex organisms, abundant microbes live inside C. sinica; however, to date, microbiome composition and diversity of the whole life cycle in C. sinica has not yet been well characterized. In the current study, we analyze the composition and biodiversity of microbiota across the whole life cycle of C. sinica by using high-throughput Illumina sequencing of the 16S ribosomal RNA gene. Collectively, Proteobacteria and Firmicutes dominated the microenvironment at all stages, but their relative abundances fluctuated by host developmental stage. Interestingly, eggs, neonates, and adults shared similar microbes, including an abundance of Rickettsia and Wolbachia. After larva feeding, Staphylococcus, Enterobacteriaceae, and Serratia were enriched in larvae and pupa, suggesting that food may serve as a major factor contributing to altered microbial community divergence at different developmental stages. Our findings demonstrated that C. sinica harbor a variety of bacteria, and that dynamic changes in community composition and relative abundances of members of its microbiome occur during different life cycle stages. Evaluating the role of these bacterial symbionts in this natural enemy may assist in developing environmental risk assessments and novel biological control strategies.

RevDate: 2019-11-14

Ote M, D Yamamoto (2019)

Impact of Wolbachia infection on Drosophila female germline stem cells.

Current opinion in insect science, 37:8-15 pii:S2214-5745(19)30077-X [Epub ahead of print].

Wolbachia pipientis, one of the most dominant insect-symbiotic bacteria, highjacks the female germline of insects for its own propagation across host generations. Such strict dependence on female gametes in trans-generational propagation has driven Wolbachia to devise ingenious strategies to enhance female fertility. In Drosophila melanogaster females with female-sterile mutant alleles of the master sex-determining gene Sex-lethal (Sxl), Wolbachia colonizing female germline stem cells (GSCs) support the maintenance of GSCs, thereby rescuing the defective ovarian development. In the germ cell cytoplasm, Wolbachia are often found in proximity to ribonucleoprotein-complex processing bodies (P bodies), where the Wolbachia-derived protein TomO interacts with RNAs encoding Nanos and Orb proteins, which support the GSC maintenance and oocyte polarization, respectively. Thus, manipulation of host RNA is the key to successful vertical transmission of Wolbachia.

RevDate: 2019-11-14

NTD Modelling Consortium Onchocerciasis Group (2019)

The World Health Organization 2030 goals for onchocerciasis: Insights and perspectives from mathematical modelling: NTD Modelling Consortium Onchocerciasis Group.

Gates open research, 3:1545.

The World Health Organization (WHO) has embarked on a consultation process to refine the 2030 goals for priority neglected tropical diseases (NTDs), onchocerciasis among them. Current goals include elimination of transmission (EOT) by 2020 in Latin America, Yemen and selected African countries. The new goals propose that, by 2030, EOT be verified in 10 countries; mass drug administration (MDA) with ivermectin be stopped in at least one focus in 34 countries; and that the proportion of the population no longer in need of MDA be equal or greater than 25%, 50%, 75% and 100% in at least 16, 14, 12, and 10 countries, respectively. The NTD Modelling Consortium onchocerciasis teams have used EPIONCHO and ONCHOSIM to provide modelling insights into these goals. EOT appears feasible in low-moderate endemic areas with long-term MDA at high coverage (≥75%), but uncertain in areas of higher endemicity, poor coverage and adherence, and where MDA has not yet, or only recently, started. Countries will have different proportions of their endemic areas classified according to these categories, and this distribution of pre-intervention prevalence and MDA duration and programmatic success will determine the feasibility of achieving the proposed MDA cessation goals. Highly endemic areas would benefit from switching to biannual or quarterly MDA and implementing vector control where possible (determining optimal frequency and duration of anti-vectorial interventions requires more research). Areas without loiasis that have not yet initiated MDA should implement biannual (preferably with moxidectin) or quarterly MDA from the start. Areas with loiasis not previously treated would benefit from implementing test-and(not)-treat-based interventions, vector control, and anti- Wolbachia therapies, but their success will depend on the levels of screening and coverage achieved and sustained. The diagnostic performance of IgG4 Ov16 serology for assessing EOT is currently uncertain. Verification of EOT requires novel diagnostics at the individual- and population-levels.

RevDate: 2019-11-12

Yin X, Zhao S, Yan B, et al (2019)

Bartonella rochalimae, B. grahamii, B. elizabethae, and Wolbachia spp. in Fleas from Wild Rodents near the China-Kazakhstan Border.

The Korean journal of parasitology, 57(5):553-559.

The Alataw Pass, near the Ebinur Lake Wetland (northwest of China) and Taldykorgan (east of Kazakhstan), is a natural habitat for wild rodents. To date, little has been done on the surveillance of Bartonella spp. and Wolbachia spp. from fleas in the region. Here we molecularly detected Bartonella spp. and Wolbachia spp. in wild rodent fleas during January and October of 2016 along the Alataw Pass-Kazakhstan border. A total of 1,706 fleas belonging to 10 species were collected from 6 rodent species. Among the 10 flea species, 4 were found to be positive for Wolbachia, and 5 flea species were positive for Bartonella. Molecular analysis indicated that i) B. rochalimae was firstly identified in Xenopsylla gerbilli minax and X. conforms conforms, ii) B. grahamii was firstly identified in X. gerbilli minax, and iii) B. elizabethae was firstly detected in Coptopsylla lamellifer ardua, Paradoxopsyllus repandus, and Nosopsyllus laeviceps laeviceps. Additionally, 3 Wolbachia endosymbionts were firstly found in X. gerbilli minax, X. conforms conforms, P. repandus, and N. laeviceps laeviceps. BLASTn analysis indicated 3 Bartonella species showed genotypic variation. Phylogenetic analysis revealed 3 Wolbachia endosymbionts were clustered into the non-Siphonaptera Wolbachia group. These findings extend our knowledge of the geographical distribution and carriers of B. rochalimae, B. grahamii, B. elizabethae, and Wolbachia spp. In the future, there is a need for China-Kazakhstan cooperation to strengthen the surveillance of flea-borne pathogens in wildlife.

RevDate: 2019-11-11

Adekunle AI, Meehan MT, ES McBryde (2019)

Mathematical analysis of a Wolbachia invasive model with imperfect maternal transmission and loss of Wolbachia infection.

Infectious Disease Modelling, 4:265-285 pii:S2468-0427(19)30029-6.

Arboviral infections, especially dengue, continue to cause significant health burden in their endemic regions. One of the strategies to tackle these infections is to replace the main vector agent, Ae. aegypti, with the ones incapable of transmitting the virus. Wolbachia, an intracellular bacterium, has shown promise in achieving this goal. However, key factors such as imperfect maternal transmission, loss of Wolbachia infection, reduced reproductive capacity and shortened life-span affect the dynamics of Wolbachia in different forms in the Ae. aegypti population. In this study, we developed a Wolbachia transmission dynamic model adjusting for imperfect maternal transmission and loss of Wolbachia infection. The invasive reproductive number that determines the likelihood of replacement of the Wolbachia-uninfected (WU) population is derived and with it, we established the local and global stability of the equilibrium points. This analysis clearly shows that cytoplasmic incompatibility (CI) does not guarantee establishment of the Wolbachia-infected (WI) mosquitoes as imperfect maternal transmission and loss of Wolbachia infection could outweigh the gains from CI. Optimal release programs depending on the level of imperfect maternal transmission and loss of Wolbachia infection are shown. Hence, it is left to decision makers to either aim for replacement or co-existence of both populations.

RevDate: 2019-11-08

Basting PJ, CM Bergman (2019)

Complete Genome Assemblies for Three Variants of the Wolbachia Endosymbiont of Drosophila melanogaster.

Microbiology resource announcements, 8(45): pii:8/45/e00956-19.

Here, we report genome assemblies for three strains of Wolbachia pipientis, assembled from unenriched, unfiltered long-read shotgun sequencing data of geographically distinct strains of Drosophila melanogaster Our simple methodology can be applied to long-read data sets of other Wolbachia-infected species with limited Wolbachia-host lateral gene transfers to produce complete assemblies for this important model symbiont.

RevDate: 2019-11-08

Almeida L, Duprez MG, Privat Y, et al (2019)

Mosquito population control strategies for fighting against arboviruses.

Mathematical biosciences and engineering : MBE, 16(6):6274-6297.

In the fight against vector-borne arboviruses, an important strategy of control of epidemic consists in controlling the population of the vector, Aedes mosquitoes in this case. Among possible actions, two techniques consist either in releasing sterile mosquitoes to reduce the size of the population (Sterile Insect Technique) or in replacing the wild population by one carrying a bacteria, called Wolbachia, blocking the transmission of viruses from insects to humans. This article addresses the issue of optimizing the dissemination protocol for each of these strategies, in order to get as close as possible to these objectives. Starting from a mathematical model describing population dynamics, we study the control problem and introduce the cost function standing for population replacement and sterile insect technique. Then, we establish some properties of the optimal control and illustrate them with numerical simulations.

RevDate: 2019-11-07

Karut K, Castle SJ, Karut ŞT, et al (2019)

Secondary endosymbiont diversity of Bemisia tabaci and its parasitoids.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(19)30330-2 [Epub ahead of print].

Cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the most important insect pests worldwide. It is known as a species complex consisting of at least 40 cryptic species. Although there are substantial data regarding species composition, parasitoids and endosymbionts of B. tabaci, data on relationship between the pest, parasitoids and endosymbionts are very restricted. Therefore, in this study, secondary endosymbionts in populations of B. tabaci and their parasitoids collected from Turkey and the USA were determined by PCR-based DNA analysis. Whitefly populations in Turkey represented both Mediterranean (MED) and Middle East-Asia Minor1 (MEAM1) genotypes from single or mixed populations of both genotypes. Arsenophonus, Rickettsia and Wolbachia were found in MED, while Hamiltonella and Rickettsia in MEAM1. Whitefly populations collected from Arizona were all MEAM1 and dually infected with Hamiltonella and Rickettsia. The aphelinid parasitoids Encarsia lutea and Eretmocerus mundus predominated in all Turkish populations. While almost all En. lutea populations were infected with Wolbachia, no endosymbionts were detected in any Er. mundus. Parasitoid species and the pattern of secondary endosymbiont infection in Arizona populations were different with Rickettsia detected only from Encarsia sophia while both Rickettsia and Wolbachia were found in Eretmocerus species. As a result, four secondary endosymbionts, namely, Rickettsia, Hamiltonella, Arsenophonus and Wolbachia, were detected from B.tabaci and its parasitoids. Among them only Wolbachia and Rickettsia were found in both the pest and parasitoids. It is conclude that further studies should be pursued to determine effect of these endosymbionts on biology of the parasitoids and success in biological control of B. tabaci.

RevDate: 2019-11-06

Layton EM, On J, Perlmutter JI, et al (2019)

Paternal Grandmother Age Affects the Strength of Wolbachia-Induced Cytoplasmic Incompatibility in Drosophila melanogaster.

mBio, 10(6): pii:mBio.01879-19.

Wolbachia are obligate intracellular bacteria that are globally distributed in half of all arthropod species. As the most abundant maternally inherited microbe in animals, Wolbachia manipulate host reproduction via reproductive parasitism strategies, including cytoplasmic incompatibility (CI). CI manifests as embryonic death when Wolbachia-modified sperm fertilize uninfected eggs but not maternally infected eggs. Thus, CI can provide a relative fitness advantage to Wolbachia-infected females and drive the infection through a population. In the genetic model Drosophila melanogaster, the Wolbachia strain wMel induces variable CI, making mechanistic studies in D. melanogaster cumbersome. Here, we demonstrate that sons of older paternal D. melanogaster grandmothers induce stronger CI than sons of younger paternal grandmothers, and we term this relationship the "paternal grandmother age effect" (PGAE). Moreover, the embryos and adult sons of older D. melanogaster grandmothers have higher Wolbachia densities, correlating with their ability to induce stronger CI. In addition, we report that Wolbachia density positively correlates with female age and decreases after mating, suggesting that females transmit Wolbachia loads that are proportional to their own titers. These findings reveal a transgenerational impact of age on wMel-induced CI, elucidate Wolbachia density dynamics in D. melanogaster, and provide a methodological advance to studies aimed at understanding wMel-induced CI in the D. melanogaster model.IMPORTANCE Unidirectional cytoplasmic incompatibility (CI) results in a postfertilization incompatibility between Wolbachia-infected males and uninfected females. CI contributes to reproductive isolation between closely related species and is used in worldwide vector control programs to drastically lower arboviral vector population sizes or to replace populations that transmit arboviruses with those resistant to transmission. Despite decades of research on the factors that influence CI, penetrance is often variable under controlled laboratory conditions in various arthropods, suggesting that additional variables influence CI strength. Here, we demonstrate that paternal D. melanogaster grandmother age influences the strength of CI induced by their sons. Older D. melanogaster females have higher Wolbachia densities and produce offspring with higher Wolbachia densities that associate with stronger CI. This work reveals a multigenerational impact of age on CI and expands our understanding of host-Wolbachia interactions and the biology of CI induced by the Wolbachia strain infecting the most widely used arthropod model, D. melanogaster.

RevDate: 2019-11-05

Liang Y, Hong Y, Mai Z, et al (2019)

Internal and External Microbial Community of the Thitarodes Moth, the Host of Ophiocordyceps sinensis.

Microorganisms, 7(11): pii:microorganisms7110517.

Ophiocordyceps sinensis is a widely known medicinal entomogenous fungus, which parasitizes the soil-borne larva of Thitarodes (Hepialidae, Lepidoptera) distributed in the Qinghai-Tibetan Plateau and its adjacent areas. Previous research has involved artificial cultivation of Chinese cordyceps (the fungus-caterpillar complex), but it is difficult to achieve large-scale cultivation because the coupling relation between the crucial microbes and their hosts is not quite clear. To clarify the influence of the internal microbial community on the occurrence of Chinese cordyceps, in this study, the unfertilized eggs of Thitarodes of different sampling sites were chosen to analyze the bacterial and fungal communities via 16S rRNA and ITS sequencing for the first time. The results showed that for bacteria, 348 genera (dominant genera include Wolbachia, Spiroplasma, Carnobacterium, Sphingobium, and Acinetobacter) belonging to 26 phyla (dominant phyla include Proteobacteria, Firmicutes, Tenericutes, Actinobacteria, Acidobacteria, and Bacteroidetes), 58 classes, 84 orders, and 120 families were identified from 1294 operational taxonomic units (OTUs). The dominant bacterial genus (Spiroplasma) may be an important bacterial factor promoting the occurrence of Chinese cordyceps. For fungi, 289 genera, mainly including Aureobasidium, Candida, and Cryptococcus, were identified, and they belonged to 5 phyla (Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota, and Zygomycota), 26 classes, 82 orders, and 165 families. Eight bacterial OTUs and 12 fungal OTUs were shared among all of the detected samples and were considered as core species. Among them, Wolbachia, Spiroplasma, Carnobacterium, Aureobasidium, and Phoma may play important roles in helping the host larva to digest foods, adapt to extreme environments, or resist pathogens. On the other hand, the external (soil) microbial community was synchronously and comparatively analyzed. Comparative analysis revealed that external microbial factors might play a more significant role in the occurrence of Chinese cordyceps, owing to the significant differences revealed by α-diversity and β-diversity analyses among different groups. In summary, the results of this study may contribute to the large-scale cultivation of Chinese cordyceps.

RevDate: 2019-10-31

Ryan PA, Turley AP, Wilson G, et al (2019)

Establishment of wMel Wolbachia in Aedes aegypti mosquitoes and reduction of local dengue transmission in Cairns and surrounding locations in northern Queensland, Australia.

Gates open research, 3:1547.

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The wMel strain of Wolbachia was backcrossed into the local Aedes aegypti genotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of Wolbachia. Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 - 99%). Conclusion: Deployment of the wMel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas.

RevDate: 2019-10-30

Kieran TJ, Arnold KMH, Thomas JC, et al (2019)

Regional biogeography of microbiota composition in the Chagas disease vector Rhodnius pallescens.

Parasites & vectors, 12(1):504 pii:10.1186/s13071-019-3761-8.

BACKGROUND: Triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Rhodnius pallescens is a major vector of Chagas disease in Panama. Understanding the microbial ecology of disease vectors is important in the development of vector management strategies that target vector survival and fitness. In this study we examined the whole-body microbial composition of R. pallescens from three locations in Panama.

METHODS: We collected 89 R. pallescens specimens using Noireau traps in Attalea butyracea palms. We then extracted total DNA from whole-bodies of specimens and amplified bacterial microbiota using 16S rRNA metabarcoding PCR. The 16S libraries were sequenced on an Illumina MiSeq and analyzed using QIIME2 software.

RESULTS: We found Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes to be the most abundant bacterial phyla across all samples. Geographical location showed the largest difference in microbial composition with northern Veraguas Province having the most diversity and Panama Oeste Province localities being most similar to each other. Wolbachia was detected in high abundance (48-72%) at Panama Oeste area localities with a complete absence of detection in Veraguas Province. No significant differences in microbial composition were detected between triatomine age class, primary blood meal source, or T. cruzi infection status.

CONCLUSIONS: We found biogeographical regions differ in microbial composition among R. pallescens populations in Panama. While overall the microbiota has bacterial taxa consistent with previous studies in triatomine microbial ecology, locality differences are an important observation for future studies. Geographical heterogeneity in microbiomes of vectors is an important consideration for future developments that leverage microbiomes for disease control.

RevDate: 2019-10-30

Martinez J, Bruner-Montero G, Arunkumar R, et al (2019)

Virus evolution in Wolbachia-infected Drosophila.

Proceedings. Biological sciences, 286(1914):20192117.

Wolbachia, a common vertically transmitted symbiont, can protect insects against viral infection and prevent mosquitoes from transmitting viral pathogens. For this reason, Wolbachia-infected mosquitoes are being released to prevent the transmission of dengue and other arboviruses. An important question for the long-term success of these programmes is whether viruses can evolve to escape the antiviral effects of Wolbachia. We have found that Wolbachia altered the outcome of competition between strains of the DCV virus in Drosophila. However, Wolbachia still effectively blocked the virus genotypes that were favoured in the presence of the symbiont. We conclude that Wolbachia did cause an evolutionary response in viruses, but this has little or no impact on the effectiveness of virus blocking.

RevDate: 2019-10-29

Newton ILG, DW Rice (2019)

The Jekyll and Hyde symbiont: could Wolbachia be a nutritional mutualist?.

Journal of bacteriology pii:JB.00589-19 [Epub ahead of print].

The most common intracellular symbiont on the planet -Wolbachia pipientis- is infamous largely for the reproductive manipulations induced in its host. However, more recent evidence suggests that this bacterium may also serve as a nutritional mutualist in certain host backgrounds and for certain metabolites. We performed a large-scale analysis of conserved gene content across all sequenced Wolbachia genomes to infer potential nutrients made by these symbionts. We review and critically evaluate the prior research supporting a beneficial role for Wolbachia and suggest future experiments to test hypotheses of metabolic provisioning.

RevDate: 2019-10-28

Kittayapong P, Ninphanomchai S, Limohpasmanee W, et al (2019)

Combined sterile insect technique and incompatible insect technique: The first proof-of-concept to suppress Aedes aegypti vector populations in semi-rural settings in Thailand.

PLoS neglected tropical diseases, 13(10):e0007771 pii:PNTD-D-18-01991 [Epub ahead of print].

BACKGROUND: Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand.

Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100-200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones.

CONCLUSIONS/SIGNIFICANCE: Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector.

RevDate: 2019-10-25

Gasser MT, Chung M, Bromley RE, et al (2019)

Complete Genome Sequence of wAna, the Wolbachia Endosymbiont of Drosophila ananassae.

Microbiology resource announcements, 8(43): pii:8/43/e01136-19.

Here, we present the complete genome sequence of the Wolbachia endosymbiont wAna, isolated from Drosophila ananassae and derived from Oxford Nanopore and Illumina sequencing. We anticipate that this will aid in Wolbachia comparative genomics and the assembly of D. ananassae specifically in regions containing extensive lateral gene transfer events.

RevDate: 2019-10-24

Staunton KM, Usher L, Prachar T, et al (2019)

A Novel Methodology For Recording Wing Beat Frequencies of Untethered Male and Female Aedes aegypti.

Journal of the American Mosquito Control Association, 35(3):169-177.

Aedes aegypti is a vector of many significant arboviruses worldwide, including dengue, Zika, chikungunya, and yellow fever viruses. With vector control methodology pivoting toward rearing and releasing large numbers of insects for either population suppression or virus-blocking, economical remote (sentinel) surveillance methods for release tracking become increasingly necessary. Recent steps in this direction include advances in optical sensors that identify and classify insects based on their wing beat frequency (WBF). As these traps are being developed, there is a strong need to better understand the environmental and biological factors influencing mosquito WBFs. Here, we developed new untethered-subject methodology to detect changes in WBFs of male and female Ae. aegypti. This new methodology involves directing an ultrasonic transducer at a free-flying subject and measuring the Doppler shift of the reflected ultrasonic continuous wave signal. This system's utility was assessed by determining its ability to confirm previous reports on the effect of temperature, body size, and age on the WBFs generated from acoustic or optical-based experiments. The presented ultrasonic method successfully detected expected trends for each factor for both male and female Ae. aegypti without the need for subject manipulation and potential impediment of natural flight dynamics due to tethering. As a result, this ultrasonic methodology provides a new method for understanding the environmental and physiological determinants of male and female WBFs that can inform the design of remote mosquito surveillance systems.

RevDate: 2019-10-23

Chen R, Su X, Chen J, et al (2019)

Wolbachia Infection in Two Species: Novel Views on the Colonization Ability of Wolbachia in Aphids.

Environmental entomology pii:5603787 [Epub ahead of print].

Wolbachia pipientis (Rickettsiales: Anaplasmataceae) is an intracellular symbiont residing in arthropods and filarial nematodes. Sixteen supergroups have been described from different host taxa. Four supergroups A, B, M, and N were found in aphids according to prior studies. The cotton aphid, Aphis gossypii, and the green peach aphid, Myzus persicae, are typical polyphagous species with global distributions. We conducted an extensive and systematic survey of Wolbachia infections in these aphids from China. High incidences of Wolbachia infection were detected. The total infection incidence was 60% in A. gossypii and 88% in M. persicae. Both aphid species were infected with supergroups A, B and M. Different incidences of infection were observed among the seven geographical regions in China, which suggested a positive relationship between Wolbachia infections and the geographical distribution of aphid species. Furthermore, multiple infection patterns (M, B, A&M, B&M, and A&B&M) were observed. Infection patterns M and B&M were detected in almost all populations. Patterns A&B&M and B showed geographical restriction in North China. Three factors can possibly influence the Wolbachia infection incidences and patterns: the geographical distribution, aphid species, and different supergroup types.

RevDate: 2019-10-23

Gómez-Zurita J (2019)

Assessment of the role of Wolbachia in mtDNA paraphyly and the evolution of unisexuality in Calligrapha (Coleoptera: Chrysomelidae).

Ecology and evolution, 9(19):11198-11214 pii:ECE35621.

Calligrapha is a New World leaf beetle genus that includes several unisexual species in northeastern North America. Each unisexual species had an independent hybrid origin involving different combinations of bisexual species. However, surprisingly, they all cluster in a single mtDNA clade and with some individuals of their parental species, which are in turn deeply polyphyletic for mtDNA. This pattern is suggestive of a selective sweep which, together with mtDNA taxonomic incongruence and occurrence of unisexuality in Calligrapha, led to hypothesize that Wolbachia might be responsible. I tested this hypothesis studying the correlation between diversity of Wolbachia and well-established mtDNA lineages in >500 specimens of two bisexual species of Calligrapha and their derived unisexual species. Wolbachia appears highly prevalent (83.4%), and fifteen new supergroup-A strains of the bacteria are characterized, belonging to three main classes: wCallA, occupying the whole species ranges, and wCallB and wCallC, narrowly parapatric, infecting beetles with highly divergent mtDNAs where they coexist. Most beetles (71.6%) carried double infections of wCallA with another sequence class. Bayesian inference of ancestral character states and association tests between bacterial diversity and the mtDNA genealogy show that each mtDNA lineage of Calligrapha has specific types of infection. Moreover, shifts can be explained by horizontal or vertical transfer from local populations to an expanding lineage and cytoplasmic incompatibility between wCallB and wCallC types, suggesting that the symbionts hitchhike with the host and are not responsible for selective mtDNA sweeps. Lack of evidence for sweeps and the fact that individuals in the unisexual clade are uninfected or infected by the widespread wCallA type indicate that Wolbachia does not induce unisexuality in Calligrapha, although they may manipulate host reproduction through cytoplasmic incompatibility.

RevDate: 2019-10-21

König K, Zundel P, Krimmer E, et al (2019)

Reproductive isolation due to prezygotic isolation and postzygotic cytoplasmic incompatibility in parasitoid wasps.

Ecology and evolution, 9(18):10694-10706 pii:ECE35588.

The reproductive barriers that prevent gene flow between closely related species are a major topic in evolutionary research. Insect clades with parasitoid lifestyle are among the most species-rich insects and new species are constantly described, indicating that speciation occurs frequently in this group. However, there are only very few studies on speciation in parasitoids. We studied reproductive barriers in two lineages of Lariophagus distinguendus (Chalcidoidea: Hymenoptera), a parasitoid wasp of pest beetle larvae that occur in human environments. One of the two lineages occurs in households preferably attacking larvae of the drugstore beetle Stegobium paniceum ("DB-lineage"), the other in grain stores with larvae of the granary weevil Sitophilus granarius as main host ("GW-lineage"). Between two populations of the DB-lineage, we identified slight sexual isolation as intraspecific barrier. Between populations from both lineages, we found almost complete sexual isolation caused by female mate choice, and postzygotic isolation, which is partially caused by cytoplasmic incompatibility induced by so far undescribed endosymbionts which are not Wolbachia or Cardinium. Because separation between the two lineages is almost complete, they should be considered as separate species according to the biological species concept. This demonstrates that cryptic species within parasitoid Hymenoptera also occur in Central Europe in close contact to humans.

RevDate: 2019-10-21

Bi J, YF Wang (2019)

The effect of the endosymbiont Wolbachia on the behavior of insect hosts.

Insect science [Epub ahead of print].

As one of the most successful intracellular symbiotic bacteria, Wolbachia can infect many arthropods and nematodes. Wolbachia infection usually affects the reproduction of their hosts to promote their own proliferation and transmission. Currently, most of the studies focus on the mechanisms of Wolbachia interactions with host reproduction. However, in addition to distribution in the reproductive tissues, Wolbachia also infect various somatic tissues of their hosts, including the brain. This raises the potential that Wolbachia may influence some somatic processes, such as behaviors in their hosts. So far, information about the effects of Wolbachia infection on host behavior is still very limited. The present review presents the current literature on different aspects of the influence of Wolbachia on various behaviors, including sleep, learning and memory, mating, feeding and aggression in their insect hosts. We then highlight ongoing scientific efforts in the field that need to address to advance this field, which can have significant implications for further developing Wolbachia as environmentally friendly biocontrol agents to control insect-borne diseases and agricultural pests. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-17

Galis F, JJM van Alphen (2019)

Parthenogenesis and developmental constraints.

Evolution & development [Epub ahead of print].

The absence of a paternal contribution in an unfertilized ovum presents two developmental constraints against the evolution of parthenogenesis. We discuss the constraint caused by the absence of a centrosome and the one caused by the missing set of chromosomes and how they have been broken in specific taxa. They are examples of only a few well-underpinned examples of developmental constraints acting at macro-evolutionary scales in animals. Breaking of the constraint of the missing chromosomes is the best understood and generally involves rare occasions of drastic changes of meiosis. These drastic changes can be best explained by having been induced, or at least facilitated, by sudden cytological events (e.g., repeated rounds of hybridization, endosymbiont infections, and contagious infections). Once the genetic and developmental machinery is in place for regular or obligate parthenogenesis, shifts to other types of parthenogenesis can apparently rather easily evolve, for example, from facultative to obligate parthenogenesis, or from pseudoarrhenotoky to haplodiploidy. We argue that the combination of the two developmental constraints forms a near-absolute barrier against the gradual evolution from sporadic to obligate or regular facultative parthenogenesis, which can probably explain why the occurrence of the highly advantageous mode of regular facultative parthenogenesis is so rare and entirely absent in vertebrates.

RevDate: 2019-10-17

Li F, Hua H, Ali A, et al (2019)

Characterization of a Bacterial Symbiont Asaia sp. in the White-Backed Planthopper, Sogatella furcifera, and Its Effects on Host Fitness.

Frontiers in microbiology, 10:2179.

The white-backed planthopper (WBPH), Sogatella furcifera Horváth (Hemiptera: Delphacidae), is an economically significant rice insect pest that harbors a primary fungal yeast-like symbiont (YLS), and some secondary bacterial symbionts like Wolbachia and Cardinium. In the present study, an additional bacterial symbiont in WBPH was characterized. Phylogenetic analysis employing the 16S rRNA gene showed a bacterium closely related to Asaia of Nilaparvata lugens and Nysius expressus, and Asaia krungthepensis. TEM observation of the bacterium showed the typical morphology of Asaia sp. with signature filamentous structures in the nucleoid region. These results indicate that the bacterium belongs to Asaia. The Asaia bacterium was detected in all the tested individual adults and tissues of the laboratory WBPH population but showed varying infection rates (ca 45%) in the field collected WBPH populations. Quantitative PCR analysis revealed that Asaia sp. were significantly more abundant in WBPH females than males, and mainly distributed in the guts, fatty bodies, and salivary glands. Asaia-infected WBPH were of shorter nymphal duration and heavier adult weight than Asaia-free WBPH, while Asaia-free WBPH comparatively fed more, indicating that Asaia plays a role in improving WBPH fitness through involvement in host's nutrient supply.

RevDate: 2019-10-16

Biwot JC, Zhang HB, Liu C, et al (2019)

Wolbachia-induced expression of kenny gene in testes affects male fertility in Drosophila melanogaster.

Insect science [Epub ahead of print].

Wolbachia are gram-negative endosymbionts that are known to cause embryonic lethality when infected male insects mate with uninfected females or with females carrying a different strain of Wolbachia, a situation characterized as cytoplasmic incompatibility (CI). However, the mechanism of CI is not yet fully understood, although recent studies on Drosophila melanogaster have achieved great progress. Here, we found that Wolbachia infection caused changes in the expressions of several immunity-related genes, including significant upregulation of kenny (key), in the testes of Drosophila melanogaster. Overexpression of key in fly testes led to a significant decrease in egg hatch rates when these flies mate with wild type females. Wolbachia-infected females could rescue this embryonic lethality. Furthermore, in key overexpressing testes TUNEL signal was significantly stronger than in the control testes, and the level of reactive oxygen species (ROS) was significantly increased. Overexpression of key also resulted in alterations of some other immunity-related gene expressions, including the downregulation of Zn72D. Knockdown of Zn72D in fly testes also led to a significant decrease in egg hatch rates. These results suggest that Wolbachia might induce the defect in male host fertility by immunity-related pathways and thus cause an oxidative damage and cell death in male testes. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-16

Chen H, Ronau JA, Beckmann JF, et al (2019)

A Wolbachia nuclease and its binding partner provide a distinct mechanism for cytoplasmic incompatibility.

Proceedings of the National Academy of Sciences of the United States of America pii:1914571116 [Epub ahead of print].

Wolbachia are endosymbiotic bacteria that infect nearly half of all arthropod species. This pandemic is due in part to their ability to increase their transmission through the female germline, most commonly by a mechanism called cytoplasmic incompatibility (CI). The Wolbachia cid operon, encoding 2 proteins, CidA and CidB, the latter a deubiquitylating enzyme (DUB), recapitulates CI in transgenic Drosophila melanogaster However, some CI-inducing Wolbachia strains lack a DUB-encoding cid operon; it was therefore proposed that the related cin operon codes for an alternative CI system. Here we show that the Wolbachia cin operon encodes a nuclease, CinB, and a second protein, CinA, that tightly binds CinB. Recombinant CinB has nuclease activity against both single-stranded and double-stranded DNA but not RNA under the conditions tested. Expression of the cin operon in transgenic male flies induces male sterility and embryonic defects typical of CI. Importantly, transgenic CinA can rescue defects in egg-hatch rates when expressed in females. Expression of CinA also rescues CinB-induced growth defects in yeast. CinB has 2 PD-(D/E)xK nuclease domains, and both are required for nuclease activity and for toxicity in yeast and flies. Our data suggest a distinct mechanism for CI involving a nuclease toxin and highlight the central role of toxin-antidote operons in Wolbachia-induced cytoplasmic incompatibility.

RevDate: 2019-10-16

Ghosh A, Jasperson D, Cohnstaedt LW, et al (2019)

Transfection of Culicoides sonorensis biting midge cell lines with Wolbachia pipientis.

Parasites & vectors, 12(1):483 pii:10.1186/s13071-019-3716-0.

BACKGROUND: Biting midges of the genus Culicoides vector multiple veterinary pathogens and are difficult to control. Endosymbionts particularly Wolbachia pipientis may offer an alternative to control populations of Culicoides and/or impact disease transmission in the form of population suppression or replacement strategies.

METHODS: Culicoides sonorensis cell lines were transfected with a Wolbachia infection using a modified shell vial technique. Infections were confirmed using PCR and cell localization using fluorescent in situ hybridization (FISH). The stability of Wolbachia infections and density was determined by qPCR. qPCR was also used to examine immune genes in the IMD, Toll and JACK/STAT pathways to determine if Wolbachia were associated with an immune response in infected cells.

RESULTS: Here we have transfected two Culicoides sonorensis cell lines (W3 and W8) with a Wolbachia infection (walbB) from donor Aedes albopictus Aa23 cells. PCR and FISH showed the presence of Wolbachia infections in both C. sonorensis cell lines. Infection densities were higher in the W8 cell lines when compared to W3. In stably infected cells, genes in the immune Toll, IMD and JAK/STAT pathways were upregulated, along with Attacin and an Attacin-like anti-microbial peptides.

CONCLUSIONS: The successful introduction of Wolbachia infections in C. sonorensis cell lines and the upregulation of immune genes, suggest the utility of using Wolbachia for a population replacement and/or population suppression approach to limit the transmission of C. sonorensis vectored diseases. Results support the further investigation of Wolbachia induced pathogen inhibitory effects in Wolbachia-infected C. sonorensis cell lines and the introduction of Wolbachia into C. sonorensis adults via embryonic microinjection to examine for reproductive phenotypes and host fitness effects of a novel Wolbachia infection.

RevDate: 2019-10-14

Tseng SP, Wetterer JK, Suarez AV, et al (2019)

Genetic Diversity and Wolbachia Infection Patterns in a Globally Distributed Invasive Ant.

Frontiers in genetics, 10:838.

Understanding the phylogeographic history of an invasive species may facilitate reconstructing the history and routes of its invasion. The longhorn crazy ant, Paratrechina longicornis, is a ubiquitous agricultural and household pest throughout much of the tropics and subtropics, but little is known about the history of its spread. Here, we examine worldwide genetic variation in P. longicornis and its associated Wolbachia bacterial symbionts. Analyses of mtDNA sequences of 248 P. longicornis workers (one per colony) from 13 geographic regions reveal two highly diverged mtDNA clades that co-occur in most of the geographic regions. These two mtDNA clades are associated with different Wolbachia infection patterns, but are not congruent with patterns of nDNA (microsatellite) variation. Multilocus sequence typing reveals two distinct Wolbachia strains in P. longicornis, namely, wLonA and wLonF. The evolutionary histories of these two strains differ; wLonA appears to be primarily transmitted maternally, and patterns of mtDNA and nDNA variation and wLonA infection status are consistent with a relatively recent Wolbachia-induced selective sweep. In contrast, the observed patterns of mtDNA variation and wLonF infections suggest frequent horizontal transfer and losses of wLonF infections. The lack of nDNA structure among sampled geographic regions coupled with the finding that numerous mtDNA haplotypes are shared among regions implies that inadvertent long-distance movement through human commerce is common in P. longicornis and has shaped the genetic structure of this invasive ant worldwide.

RevDate: 2019-10-11

Caputo B, Moretti R, Manica M, et al (2019)

A bacterium against the tiger: preliminary evidence of fertility reduction after release of Aedes albopictus males with manipulated Wolbachia infection in an Italian urban area.

Pest management science [Epub ahead of print].

BACKGROUND: Novel tools are needed to reduce nuisance and risk of exotic arbovirus transmission associated with the colonization of temperate regions by Aedes albopictus. Incompatible Insect Technique (IIT) is a population suppression approach based on cytoplasmic incompatibility between males with manipulated endosymbionts and wild females. Here we present the results of the first field experiment in Europe to assess the capacity of an Ae. albopictus line (ARwP) deprived of its natural endosymbiont Wolbachia and transinfected with a Wolbachia strain from the mosquito Culex pipiens - to sterilize wild females.

RESULTS: We released ~4500 ARwP males weekly for 6 weeks in a green area within urban Rome (Italy) and carried out egg (N = 13 442), female (N = 128) and male (N = 352) collections. Egg (N = 13 783) and female (N = 48) collections were also carried out in two untreated Control Sites. The percentage of viable eggs during releases was on average significantly lower in Treated than in Control Sites, with the highest difference (16%) after the fourth release. The ARwP/wild male ratio in the release spots between day-3 from the first ARwP male release and day-7 after the last release was on average 7:10. Released males survived up to two weeks. About 30% of the females collected in the release spots showed 100% sterility and 20% a strongly reduced fertility compared to Control Sites.

CONCLUSIONS: Results support the potential of IIT as a tool to contribute to Ae. albopictus control in the urban context and stress the need of larger field trials to evaluate the cost-efficacy of the approach in suppressing wild populations. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-10

Becking T, Chebbi MA, Giraud I, et al (2019)

Sex chromosomes control vertical transmission of feminizing Wolbachia symbionts in an isopod.

PLoS biology, 17(10):e3000438 pii:PBIOLOGY-D-19-01022 [Epub ahead of print].

Microbial endosymbiosis is widespread in animals, with major ecological and evolutionary implications. Successful symbiosis relies on efficient vertical transmission through host generations. However, when symbionts negatively affect host fitness, hosts are expected to evolve suppression of symbiont effects or transmission. Here, we show that sex chromosomes control vertical transmission of feminizing Wolbachia endosymbionts in the isopod Armadillidium nasatum. Theory predicts that the invasion of an XY/XX species by cytoplasmic sex ratio distorters is unlikely because it leads to fixation of the unusual (and often lethal or infertile) YY genotype. We demonstrate that A. nasatum X and Y sex chromosomes are genetically highly similar and that YY individuals are viable and fertile, thereby enabling Wolbachia spread in this XY-XX species. Nevertheless, we show that Wolbachia cannot drive fixation of YY individuals, because infected YY females do not transmit Wolbachia to their offspring, unlike XX and XY females. The genetic basis fits the model of a Y-linked recessive allele (associated with an X-linked dominant allele), in which the homozygous state suppresses Wolbachia transmission. Moreover, production of all-male progenies by infected YY females restores a balanced sex ratio at the host population level. This suggests that blocking of Wolbachia transmission by YY females may have evolved to suppress feminization, thereby offering a whole new perspective on the evolutionary interplay between microbial symbionts and host sex chromosomes.

RevDate: 2019-10-10

Nainu F, Trenerry A, KN Johnson (2019)

Wolbachia-mediated antiviral protection is cell-autonomous.

The Journal of general virology [Epub ahead of print].

Vector-borne viral diseases pose significant risks to human health. To control the transmission of these viruses, a number of approaches are required. The ability of the intracellular bacteria Wolbachia to limit viral accumulation and transmission in some arthropod hosts, highlights its potential as a biocontrol agent. Whilst Wolbachia can reduce the transmission of several epidemiologically important viruses, protection is not consistent amongst all insects, viruses and strains of Wolbachia, which confounds elucidation of the mechanisms that underly this protection. Evidence of different mechanisms has emerged, but is not always consistent, suggesting the tripartite interaction may be complex. Here we provide evidence that Wolbachia-mediated antiviral protection is dependent on the presence of Wolbachia in individual cells, and cannot be conferred to surrounding cells. Our results suggest that protection is cell-autonomous, and this has several mechanistic implications, which can direct future research.

RevDate: 2019-10-09

Wang X, Xiong X, Cao W, et al (2019)

Genome assembly of the A-group Wolbachia in Nasonia oneida using linked-reads technology.

Genome biology and evolution pii:5584270 [Epub ahead of print].

Wolbachia are obligate intracellular bacteria which commonly infect various nematode and arthropod species. Genome sequences have been generated from arthropod samples following enrichment for the intracellular bacteria, and genomes have also been assembled from arthropod whole-genome sequencing projects. However, these methods remain challenging for infections that occur at low titers in hosts. Here we report the first Wolbachia genome assembled from host sequences using 10X Genomics linked-reads technology. The high read depth attainable by this method allows for recovery of intracellular bacteria that are at low concentrations. Based on the depth differences (714X for the insect and 59X for the bacterium), we assembled the genome of a Wolbachia in the parasitoid jewel wasp species Nasonia oneida. The final draft assembly consists of 1,293,406 bp in 47 scaffolds with 1,114 coding genes and 97.01% genome completeness assessed by checkM. Comparisons of the five Multi Locus Sequence Typing genes revealed that the sequenced Wolbachia genome is the A1 strain (henceforth wOneA1) previously reported in N. oneida. Pyrosequencing confirms that the wasp strain lacks A2 and B types previously detected in this insect, which were likely lost during laboratory culturing. Assembling bacterial genomes from host genome projects can provide an effective method for sequencing bacterial genomes, even when the infections occur at low density in sampled tissues.

RevDate: 2019-10-09

Bing XL, Lu YJ, Xia CB, et al (2019)

Transcriptome of Tetranychus urticae embryos reveals insights into Wolbachia-induced cytoplasmic incompatibility.

Insect molecular biology [Epub ahead of print].

The endosymbiont Wolbachia is known for manipulating host reproduction in selfish ways. However, the molecular mechanisms have not yet been investigated in embryos. Here, we found that Wolbachia had no effect on the number of deposited eggs in Tetranychus urticae Koch (Acari: Tetranychidae) but caused two types of reproductive manipulation: killing uninfected female embryos via cytoplasmic incompatibility (CI) and increasing the hatch ratio of infected female embryos. RNA sequencing analyses showed that 145 genes were differentially expressed between Wolbachia-infected (WI) embryos and Wolbachia-uninfected (WU) embryos. Wolbachia infection down-regulated mRNA expression of glutathione S-transferase that could buffer oxidative stress. In addition, 1613 and 294 genes were identified as CI-specific up/down-regulated genes. Compared to WU and WI embryos, embryos of CI cross strongly expressed genes involved in transcription, translation, tissue morphogenesis, DNA damage, and mRNA surveillance. In contrast, most of the genes associated with energy production and metabolism were down-regulated in the CI embryos compared to WU and WI embryos, which provides some clues to the cause of death of CI embryos. These results identify several genes that could be candidates for explaining Wolbachia-induced CI. Our data formed a basis to help elucidate the molecular consequences of CI in embryos. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-09

Li F, Li P, Hua H, et al (2019)

Diversity, Tissue Localization, and Infection Pattern of Bacterial Symbionts of the White-Backed Planthopper, Sogatella furcifera (Hemiptera: Delphacidae).

Microbial ecology pii:10.1007/s00248-019-01433-4 [Epub ahead of print].

The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is a destructive pest of rice. Bacterial symbionts play an important role in insect hosts, especially hemipteran hosts. This study was designed to examine the bacterial symbionts of the WBPH using 16S rDNA high-throughput sequencing. A total of 63 and 177 operational taxonomic units (OTUs) were identified in females and males of three WBPH populations, respectively. These OTUs included bacteria of 75 genera from 11 phyla, where Wolbachia, Cardinium, and Asaia were the dominant genera, accounting for over 97.99% of all the symbiotic bacteria. Fluorescence in situ hybridization detected Wolbachia, Cardinium, and Asaia in the salivary glands, guts, testes, and eggs of the WBPH, indicating the potential for both horizontal and vertical transmission. Moreover, the infection pattern of the three dominant bacterial symbionts was detected in six WBPH populations. The frequencies of Wolbachia infection of females and Cardinium infection of both sexes were over 96.7%. Wolbachia infection of males ranged between 46.7 and 63.3%, which was significantly lower than that observed for females. Asaia infection of both sexes varied substantially among the populations. These results indicate that the complex host-symbiotic bacteria interaction is influenced by host sex and geographical origin and potentially by the transmission modes of the symbionts.

RevDate: 2019-10-08

Reynolds LA, Hornett EA, Jiggins CD, et al (2019)

Suppression of Wolbachia-mediated male-killing in the butterfly Hypolimnas bolina involves a single genomic region.

PeerJ, 7:e7677 pii:7677.

Background: Sex ratio distorting agents (maternally inherited symbionts and meiotically-driving sex chromosomes) are common in insects. When these agents rise to high frequencies they create strong population sex ratio bias and selection then favours mutations that act to restore the rare sex. Despite this strong selection pressure, the evolution of mutations that suppress sex ratio distorting elements appears to be constrained in many cases, where sex-biased populations persist for many generations. This scenario has been observed in the butterfly Hypolimnas bolina, where Wolbachia-mediated male killing endured for 800-1,000 generations across multiple populations before the evolution of suppression. Here we test the hypothesis that this evolutionary lag is the result of suppression being a multilocus trait requiring multiple mutations.

Methods: We developed genetic markers, based on conservation of synteny, for each H. bolina chromosome and verified coverage using recombinational mapping. We then used a Wolbachia-infected mapping family to assess each chromosome for the presence of loci required for male survival, as determined by the presence of markers in all surviving sons.

Results: Informative markers were obtained for each of the 31 chromosomes in H. bolina. The only marker that cosegregated with suppression was located on chromosome 25. A genomic region necessary for suppression has previously been located on this chromosome. We therefore conclude that a single genomic region of the H. bolina genome is necessary for male-killing suppression.

Discussion: The evolutionary lag observed in our system is not caused by a need for changes at multiple genomic locations. The findings favour hypotheses in which either multiple mutations are required within a single genomic region, or the suppressor mutation is a singularly rare event.

RevDate: 2019-09-30

Voronin D, Schnall E, Grote A, et al (2019)

Pyruvate produced by Brugia spp. via glycolysis is essential for maintaining the mutualistic association between the parasite and its endosymbiont, Wolbachia.

PLoS pathogens, 15(9):e1008085 pii:PPATHOGENS-D-19-01315 [Epub ahead of print].

Human parasitic nematodes are the causative agents of lymphatic filariasis (elephantiasis) and onchocerciasis (river blindness), diseases that are endemic to more than 80 countries and that consistently rank in the top ten for the highest number of years lived with disability. These filarial nematodes have evolved an obligate mutualistic association with an intracellular bacterium, Wolbachia, a symbiont that is essential for the successful development, reproduction, and survival of adult filarial worms. Elimination of the bacteria causes adult worms to die, making Wolbachia a primary target for developing new interventional tools to combat filariases. To further explore Wolbachia as a promising indirect macrofilaricidal drug target, the essential cellular processes that define the symbiotic Wolbachia-host interactions need to be identified. Genomic analyses revealed that while filarial nematodes encode all the enzymes necessary for glycolysis, Wolbachia does not encode the genes for three glycolytic enzymes: hexokinase, 6-phosphofructokinase, and pyruvate kinase. These enzymes are necessary for converting glucose into pyruvate. Wolbachia, however, has the full complement of genes required for gluconeogenesis starting with pyruvate, and for energy metabolism via the tricarboxylic acid cycle. Therefore, we hypothesized that Wolbachia might depend on host glycolysis to maintain a mutualistic association with their parasitic host. We did conditional experiments in vitro that confirmed that glycolysis and its end-product, pyruvate, sustain this symbiotic relationship. Analysis of alternative sources of pyruvate within the worm indicated that the filarial lactate dehydrogenase could also regulate the local intracellular concentration of pyruvate in proximity to Wolbachia and thus help control bacterial growth via molecular interactions with the bacteria. Lastly, we have shown that the parasite's pyruvate kinase, the enzyme that performs the last step in glycolysis, could be a potential novel anti-filarial drug target. Establishing that glycolysis is an essential component of symbiosis in filarial worms could have a broader impact on research focused on other intracellular bacteria-host interactions where the role of glycolysis in supporting intracellular survival of bacteria has been reported.

RevDate: 2019-09-30

Gawande SJ, Anandhan S, Ingle A, et al (2019)

Microbiome profiling of the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae).

PloS one, 14(9):e0223281 pii:PONE-D-19-14970.

The gut microbial community structure of adult Thrips tabaci collected from 10 different agro-climatically diverse locations of India was characterized by using the Illumina MiSeq platform to amplify the V3 region of the 16S rRNA gene of bacteria present in the sampled insects. Analyses were performed to study the bacterial communities associated with Thrips tabaci in India. The complete bacterial metagenome of T. tabaci was comprised of 1662 OTUs of which 62.25% belong to known and 37.7% of unidentified/unknown bacteria. These OTUs constituted 21 bacterial phyla of 276 identified genera. Phylum Proteobacteria was predominant, followed by Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Additionally, the occurrence of the reproductive endosymbiont, Wolbachia was detected at two locations (0.56%) of the total known OTUs. There is high variation in diversity and species richness among the different locations. Alpha-diversity metrics indicated the higher gut bacterial diversity at Bangalore and lowest at Rahuri whereas higher bacterial species richness at T. tabaci samples from Imphal and lowest at Jhalawar. Beta diversity analyses comparing bacterial communities between the samples showed distinct differences in bacterial community composition of T. tabaci samples from different locations. This paper also constitutes the first record of detailed bacterial communities associated with T. tabaci. The location-wise variation in microbial metagenome profile of T. tabaci suggests that bacterial diversity might be governed by its population genetic structure, environment and habitat.

RevDate: 2019-09-30

Detcharoen M, Arthofer W, Schlick-Steiner BC, et al (2019)

Wolbachia megadiversity: 99% of these microorganismic manipulators unknown.

FEMS microbiology ecology pii:5579019 [Epub ahead of print].

Wolbachia (Alphaproteobacteria) are the most widespread endosymbionts of arthropods, manipulating their hosts by various means to maximize the number of host individuals infected. Based on quantitative analyses of the published literature from Web of Science® and of DNA sequences of arthropod-hosted Wolbachia from GenBank, we made plausible that less than one % of the expected 100,000 strains of Wolbachia in arthropods is known. Our findings suggest that more and globally better coordinated efforts in screening arthropods are needed to explore the true Wolbachia diversity and to help us understand the ecology and evolution of these host-endosymbiont interactions.

RevDate: 2019-09-30

Huang K, Kelly PJ, Zhang J, et al (2019)

Molecular Detection of Bartonella spp. in China and St. Kitts.

The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale, 2019:3209013.

Bartonella are vector-borne hemotropic bacteria that infect a wide variety of hosts, including people. While there are PCR assays that can identify individual or groups of Bartonella, there is no reliable molecular method to simultaneously detect all species while maintaining genus specificity and sensitivity. By comparing highly conserved 16S rRNA sequences of the better-recognized Bartonella spp. on GenBank, we selected primers and probes for a genus-specific pan-Bartonella FRET-qPCR. Then, a gltA-based Bartonella PCR was established by selecting primers for a highly variable region of gltA, of which the sequenced amplicons could identify individual Bartonella spp. The pan-Bartonella FRET-qPCR did not detect negative controls (Brucella spp., Anaplasma spp., Rickettsia spp., Coxiella burnetii, and Wolbachia) but reliably detected as few as two copies of the positive control (Bartonella henselae) per reaction. There was complete agreement between the pan-Bartonella FRET-qPCR and the gltA-based Bartonella PCR in detecting Bartonella in convenience test samples from China and St. Kitts: cats (26%; 81/310), Ctenocephalides felis (20%; 12/60), cattle (24%; 23/98), and donkeys (4%; 1/20). Sequencing of the gltA-based Bartonella PCR products revealed B. henselae (70%; 57/81) and B. clarridgeiae (30%; 24/81) in cats and C. felis (67%; 8/12, and 33%; 4/12, respectively) and B. bovis in cattle (23.5%; 23/98) and donkeys (4.0%; 1/24). The pan-Bartonella FRET-qPCR and gltA-based Bartonella PCR we developed are highly sensitive and specific in detecting recognized Bartonella spp. in a single reaction. The pan-Bartonella FRET-qPCR is convenient requiring no gel electrophoresis and providing copy numbers, while the gltA-based Bartonella PCR reliably differentiates individual Bartonella species. The use of these PCRs should greatly facilitate large-scale surveillance studies and the diagnosis of infections in clinical samples.

RevDate: 2019-09-26

Andersen BJ, Rosa BA, Kupritz J, et al (2019)

Systems analysis-based assessment of post-treatment adverse events in lymphatic filariasis.

PLoS neglected tropical diseases, 13(9):e0007697 pii:PNTD-D-19-00756.

BACKGROUND: Lymphatic filariasis (LF) is a neglected tropical disease, and the Global Program to Eliminate LF delivers mass drug administration (MDA) to 500 million people every year. Adverse events (AEs) are common after LF treatment.

To better understand the pathogenesis of AEs, we studied LF-patients from a treatment trial. Plasma levels of many filarial antigens increased post-treatment in individuals with AEs, and this is consistent with parasite death. Circulating immune complexes were not elevated in these participants, and the classical complement cascade was not activated. Multiple cytokines increased after treatment in persons with AEs. A transcriptomic analysis was performed for nine individuals with moderate systemic AEs and nine matched controls. Differential gene expression analysis identified a significant transcriptional signature associated with post-treatment AEs; 744 genes were upregulated. The transcriptional signature was enriched for TLR and NF-κB signaling. Increased expression of seven out of the top eight genes upregulated in persons with AEs were validated by qRT-PCR, including TLR2.

CONCLUSIONS/SIGNIFICANCE: This is the first global study of changes in gene expression associated with AEs after treatment of lymphatic filariasis. Changes in cytokines were consistent with prior studies and with the RNAseq data. These results suggest that Wolbachia lipoprotein is involved in AE development, because it activates TLR2-TLR6 and downstream NF-κB. Additionally, LPS Binding Protein (LBP, which shuttles lipoproteins to TLR2) increased post-treatment in individuals with AEs. Improved understanding of the pathogenesis of AEs may lead to improved management, increased MDA compliance, and accelerated LF elimination.

RevDate: 2019-09-24

Bonneau M, Caputo B, Ligier A, et al (2019)

Variation in Wolbachia cidB gene, but not cidA, is associated with cytoplasmic incompatibility mod phenotype diversity in Culex pipiens.

Molecular ecology [Epub ahead of print].

Endosymbiotic Wolbachia bacteria are to date considered the most widespread symbionts in arthropods and are the cornerstone of major biological control strategies. Such a high prevalence, is based on the ability of Wolbachia to manipulate their hosts' reproduction. One manipulation called "cytoplasmic incompatibility (CI)" is based on the death of the embryos generated by crosses between infected males and uninfected females or between individuals infected with incompatible Wolbachia strains. CI can be seen as a modification-rescue system (or mod-resc) in which paternal Wolbachia produce mod factors, inducing embryonic defects, unless the maternal Wolbachia produce compatible resc factors. Transgenic experiments in Drosophila melanogaster and Saccharomyces cerevisiae converged towards a model where the cidB Wolbachia gene is involved in the mod function while cidA is involved in the resc function. However, as cidA expression in Drosophila males was required to observe CI, it has been proposed that cidA could be involved in both resc and mod functions. A recent correlative study in natural Culex pipiens mosquito populations has revealed an association between specific cidA and cidB variations and changes in 'mod phenotype', also suggesting a role for both these genes in mod diversity. Here, by studying cidA and cidB genomic repertoires of individuals from newly sampled natural C. pipiens populations harbouring wPipIV strains from North Italy, we reinforce the link between cidB variation and 'mod phenotype' variation fostering the involvement of cidB in the 'mod phenotype' diversity. However, no association between any cidA variants or combination of cidA variants and 'mod phenotype' variation was observed. Taken together our results in natural C. pipiens populations do not support the involvement of cidA in 'mod phenotype' variation.

RevDate: 2019-09-24

Avtzis DN, Schebeck M, Petsopoulos D, et al (2019)

New Data on the Range Expansion of the Thaumetopoea pityocampa (Lepidoptera: Notodontidae) 'ENA clade' in Greece: The Role of Bacterial Endosymbionts.

Journal of economic entomology pii:5573191 [Epub ahead of print].

The pine processionary moth, Thaumetopoea pityocampa (Denis and Schiffermüller), is an important insect in the Mediterranean region, as it defoliates pines and its urticating hairs can cause allergic reactions in humans and animals. Moreover, this species exhibits an interesting genetic structure as recently a distinct East-North African mtDNA lineage ('ENA clade') has been described. This clade has been recently detected in Greek populations where it has currently expanded its range by replacing the 'endemic' T. pityocampa lineages. Here, we report new data on the rapid spread of 'ENA clade' in the Greek island Evoia in only a few years. As the underlying mechanisms of the 'ENA clade' range expansion has not been studied so far, we screened T. pityocampa for an infection with the heritable bacterial endosymbionts Wolbachia (Bacteria: Anaplasmataceae), Cardinium (Bacteria: Bacteroidaceae), Rickettsia (Bacteria: Rickettsiaceae) and Spiroplasma (Bacteria: Spiroplasmataceae). These bacteria can manipulate the reproduction of infected hosts, something that could potentially explain the rapid spread of 'ENA clade' lineage. Therefore, we screened 28 individuals that exhibited T. pityocampa 'ENA clade' and 'endemic' T. pityocampa haplotypes from nine populations scattered all over Greece. None of them was infected with any of the four endosymbionts, suggesting that these bacteria do not cause reproductive manipulations in T. pityocampa lineages and, thus, other factors should be explored in future research efforts.

RevDate: 2019-09-24

Ogawa M, Takahashi M, Matsutani M, et al (2019)

Obligate intracellular bacteria diversity in unfed Leptotrombidium scutellare larvae highlights novel bacterial endosymbionts of mites.

Microbiology and immunology [Epub ahead of print].

It is well known that the mite Leptotrombidium scutellare carries the pathogen of scrub typhus, Orientia tsutsugamushi. However, our understanding of other bacterial endosymbionts of mites is limited. In this study, we investigated the diversity of the obligate intracellular bacteria carried by L. scutellare using 16S rRNA gene amplicon analysis with next-generation sequencing. The results showed that the detected bacteria were classified into the genera Rickettsia, Wolbachia, and Rickettsiella and an unknown genus of the order Rickettsiales. For further classification of the detected bacteria, a representative read that was most closely related to the assigned taxonomic classification was subjected to homology search and phylogenic analysis. The results showed that some bacteria of the genus Rickettsia were identical or very close to the human pathogens Rickettsia akari, R. aeschlimannii, R. felis, and R. australis. The genetic distance between genus Wolbachia bacteria in the present study and in previous reports is highly indicative that the bacteria in the present study can be classified as a new taxon of Wolbachia. In this study, we detected obligate intracellular bacteria from unfed mites; thus, the mites did not acquire bacteria from infected animals or any other infectious sources. Finally, the present study demonstrated that various and novel bacterial endosymbionts of mites, in addition to O. tsutsugamushi, might uniquely evolve with the host mites throughout overlapping generations of the mite life cycle . The roles of the bacteria in mites and their pathogenicity should be further examined in studies based on bacterial isolation. This article is protected by copyright. All rights reserved.

RevDate: 2019-09-19

Sanaei E, Husemann M, Seiedy M, et al (2019)

Global genetic diversity, lineage distribution, and Wolbachia infection of the alfalfa weevil Hypera postica (Coleoptera: Curculionidae).

Ecology and evolution, 9(17):9546-9563 pii:ECE35474.

The alfalfa weevil (Hypera postica) is a well-known example of a worldwide-distributed pest with high genetic variation. Based on the mitochondrial genes, the alfalfa weevil clusters into two main mitochondrial lineages. However, there is no clear picture of the global diversity and distribution of these lineages; neither the drivers of its diversification are known. However, it appears likely that historic demographic events including founder effects played a role. In addition, Wolbachia, a widespread intracellular parasite/symbiont, likely played an important role in the evolution of the species. Wolbachia infection so far was only detected in the Western lineage of H. postica with no information on the infecting strain, its frequency, and its consequences on the genetic diversity of the host. We here used a combination of mitochondrial and nuclear sequences of the host and sequence information on Wolbachia to document the distribution of strains and the degree of infection. The Eastern lineage has a higher genetic diversity and is found in the Mediterranean, the Middle East, Eastern Europe, and eastern America, whereas the less diverse Western lineage is found in Central Europe and the western America. Both lineages are infected with the same common strain of Wolbachia belonging to Supergroup B. Based on neutrality tests, selection tests, and the current distribution and diversification of Wolbachia in H. postica, we suggested the Wolbachia infection did not shape genetic diversity of the host. The introduced populations in the United States are generally genetically less diverse, which is in line with founder effects.

RevDate: 2019-09-18

Dincă V, Lee KM, Vila R, et al (2019)

The conundrum of species delimitation: a genomic perspective on a mitogenetically super-variable butterfly.

Proceedings. Biological sciences, 286(1911):20191311.

The Palaearctic butterfly Melitaea didyma stands out as one of the most striking cases of intraspecific genetic differentiation detected in Lepidoptera: 11 partially sympatric mitochondrial lineages have been reported, displaying levels of divergence of up to 7.4%. To better understand the evolutionary processes underlying the diversity observed in mtDNA, we compared mtDNA and genome-wide SNP data using double-digest restriction site-associated DNA sequencing (ddRADseq) results from 93 specimens of M. didyma ranging from Morocco to eastern Kazakhstan. We found that, between ddRADseq and mtDNA results, there is a match only in populations that probably remained allopatric for long periods of time. Other mtDNA lineages may have resulted from introgression events and were probably affected by Wolbachia infection. The five main ddRADseq clades supported by STRUCTURE were parapatric or allopatric and showed high pairwise FST values, but some were also estimated to display various levels of gene flow. Melitaea didyma represents one of the first cases of deep mtDNA splits among European butterflies assessed by a genome-wide DNA analysis and reveals that the interpretation of patterns remains challenging even when a high amount of genomic data is available. These findings actualize the ongoing debate of species delimitation in allopatry, an issue probably of relevance to a significant proportion of global biodiversity.

RevDate: 2019-09-13

Després L (2019)

One, two or more species? Mitonuclear discordance and species delimitation.

Molecular ecology [Epub ahead of print].

Delimiting species boundaries is central to understand ecological and evolutionary processes, and to monitor biodiversity patterns over time and space. Yet, most of our current knowledge on animal diversity and phylogeny relies on morphological and mitochondrial (mt) DNA variation, a popular molecular marker also used as a barcode to assign samples to species. For morphologically undistinguishable sympatric species (cryptic species), the congruence of several independent markers is necessary to define separate species. Nuclear markers are becoming more accessible, and have confirmed that cryptic species are widespread in all animal phyla (Fišer, Robinson, & Malard, 2018). However, striking differences between the mitochondrial and nuclear variation patterns are also commonly found within single species. Mitonuclear discordance can result from incomplete lineage sorting, sex-biased dispersal, asymmetrical introgression, natural selection or Wolbachia-mediated genetic sweeps. But more generally, the distinct mode of transmission of these two types of markers (maternal vs. biparental) is sufficient to explain their distinct sensitivity to purely demographic events such as spatial range and population size fluctuations over time. In a From the Cover manuscript in this issue of Molecular Ecology, Hijonosa et al. (2019) show that highly divergent mtDNA lineages coexist in a widespread European butterfly (Figure 1). None of the hundreds of nuclear markers analyzed was associated with mt lineages, nor was Wolbachia variation. These findings rule out the presence of cryptic species but shed light on complex demographic history of lineage divergence/fusion during the Pleistocene climatic fluctuations, and pave the way to a better integration of both mt and nuclear information in demographic models.

RevDate: 2019-09-12

Schwartz RA, Al-Qubati Y, Zieleniewski Ł, et al (2019)

Onchocerciasis (river blindness): larva-induced eczema (onchodermatitis) from an important oculocutaneous tropical disease spilling over into North America and Europe.

International journal of dermatology [Epub ahead of print].

Onchocerciasis is a leading cause of blindness in the world. It may be seen in temperate climates of the United States and Europe in immigrants and travelers from endemic regions, often linked to poverty and war. One should be aware of an incubation period that can be up to 15 months. In its early stage and throughout its course, onchocerciasis has noteworthy skin findings, facilitating diagnosis, as onchodermatitis resembles common eczema with variable degrees of papular, lichenoid, atrophic, and pigmentary alterations, features not suggestive if one is unaware of an individual's immigration and travel history. The same concept applies for the encysted worms (onchocercomas), as they tend to appear as common skin cysts and benign neoplasms. New methods can be employed to increase diagnostic sensitivity and specificity. Ivermectin is the gold standard of therapy, the use of which has almost miraculously eliminated this disease from large areas of the earth. However, its effect remains isolated to microfilariae and can be devastating in those coinfected with Loa loa. Recently, the symbiotic relationship between adult worms and Wolbachia bacteria has been discovered and, with it, the possibility of adding doxycycline as a treatment option. We also discuss coinfection with HIV and other diseases.

RevDate: 2019-09-11

Meng L, Li X, Cheng X, et al (2019)

16S rRNA Gene Sequencing Reveals a Shift in the Microbiota of Diaphorina citri During the Psyllid Life Cycle.

Frontiers in microbiology, 10:1948.

The Asian citrus psyllid (Diaphorina citri) is a major pest of citrus trees as it transmits Candidatus Liberibacter asiaticus (CLas). The composition of a host's microbiota can affect the evolution and ecological distribution of the host. This study monitored the compositional shifts in the citrus psyllid microbiota through all the life stages (egg, nymph 1-5 stages, and adult) by next-generation sequencing (NGS) and quantitative real-time PCR. There were clear differences in both α- and β-diversity of microbiota through the psyllid life stages. Microbiota diversity was markedly higher in the nymph 2-5 stages than in the adult, egg, and nymph 1 stages. Proteobacteria were dominant in all the life stages of D. citri, representing >97.5% of the total bacterial community, and Candidatus Profftella armature was the dominant genus in all the life stages. Data from the qPCR analysis showed an exponential increase in the populations of three D. citri endosymbionts: Candidatus Profftella armature, Candidatus Carsonella ruddii, and Wolbachia. The gut bacterium Pantoea was present in all the life stages, but it was markedly higher in the nymph 2-5 stages. The microbiota composition substantially differed among the egg-nymph 1, nymphs 2-5, and adult stages. Therefore, we successfully characterized the microbiota dynamics and thus identified a microbiota shift during the life cycle of D. citri by 16S rRNA gene sequencing and quantitative PCR. Moreover, 16S rRNA gene sequencing suggested that D. citri acquired the ability to bear CLas in the nymph 1 stage. This study enhances our understanding of microbial establishment in the developing D. citri and provides a reference resource for the identification of potential biocontrol approaches against this pest.

RevDate: 2019-09-10

Ross PA, Turelli M, AA Hoffmann (2019)

Evolutionary Ecology of Wolbachia Releases for Disease Control.

Annual review of genetics [Epub ahead of print].

Wolbachia is an endosymbiotic Alphaproteobacteria that can suppress insect-borne diseases through decreasing host virus transmission (population replacement) or through decreasing host population density (population suppression). We contrast natural Wolbachia infections in insect populations with Wolbachia transinfections in mosquitoes to gain insights into factors potentially affecting the long-term success of Wolbachia releases. Natural Wolbachia infections can spread rapidly, whereas the slow spread of transinfections is governed by deleterious effects on host fitness and demographic factors. Cytoplasmic incompatibility (CI) generated by Wolbachia is central to both population replacement and suppression programs, but CI in nature can be variable and evolve, as can Wolbachia fitness effects and virus blocking. Wolbachia spread is also influenced by environmental factors that decrease Wolbachia titer and reduce maternal Wolbachia transmission frequency. More information is needed on the interactions between Wolbachia and host nuclear/mitochondrial genomes, the interaction between invasion success and local ecological factors, and the long-term stability of Wolbachia-mediated virus blocking. Expected final online publication date for the Annual Review of Genetics, Volume 53 is November 23, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RevDate: 2019-09-10

Perlmutter JI, Bordenstein SR, Unckless RL, et al (2019)

The phage gene wmk is a candidate for male killing by a bacterial endosymbiont.

PLoS pathogens, 15(9):e1007936 pii:PPATHOGENS-D-19-01066.

Wolbachia are the most widespread maternally-transmitted bacteria in the animal kingdom. Their global spread in arthropods and varied impacts on animal physiology, evolution, and vector control are in part due to parasitic drive systems that enhance the fitness of infected females, the transmitting sex of Wolbachia. Male killing is one common drive mechanism wherein the sons of infected females are selectively killed. Despite decades of research, the gene(s) underlying Wolbachia-induced male killing remain unknown. Here using comparative genomic, transgenic, and cytological approaches in fruit flies, we identify a candidate gene in the eukaryotic association module of Wolbachia prophage WO, termed WO-mediated killing (wmk), which transgenically causes male-specific lethality during early embryogenesis and cytological defects typical of the pathology of male killing. The discovery of wmk establishes new hypotheses for the potential role of phage genes in sex-specific lethality, including the control of arthropod pests and vectors.

RevDate: 2019-09-10

Fisher ML, Levine JF, Guy JS, et al (2019)

Lack of influence by endosymbiont Wolbachia on virus titer in the common bed bug, Cimex lectularius.

Parasites & vectors, 12(1):436 pii:10.1186/s13071-019-3694-2.

BACKGROUND: The common bed bug, Cimex lectularius, is an obligatory blood-feeding ectoparasite that requires a blood meal to molt and produce eggs. Their frequent biting to obtain blood meals and intimate association with humans increase the potential for disease transmission. However, despite more than 100 years of inquiry into bed bugs as potential disease vectors, they still have not been conclusively linked to any pathogen or disease. This ecological niche is extraordinarily rare, given that nearly every other blood-feeding arthropod is associated with some type of human or zoonotic disease. Bed bugs rely on the bacteria Wolbachia as an obligate endosymbiont to biosynthesize B vitamins, since they acquire a nutritionally deficient diet, but it is unknown if Wolbachia confers additional benefits to its bed bug host. In some insects, Wolbachia induces resistance to viruses such as Dengue, Chikungunya, West Nile, Drosophila C and Zika, and primes the insect immune system in other blood-feeding insects. Wolbachia might have evolved a similar role in its mutualistic association with the bed bug. In this study, we evaluated the influence of Wolbachia on virus replication within C. lectularius.

METHODS: We used feline calicivirus as a model pathogen. We fed 40 bed bugs from an established line of Wolbachia-cured and a line of Wolbachia-positive C. lectularius a virus-laden blood meal, and quantified the amount of virus over five time intervals post-feeding. The antibiotic rifampicin was used to cure bed bugs of Wolbachia.

RESULTS: There was a significant effect of time post-feeding, as the amount of virus declined by ~90% over 10 days in both groups, but no significant difference in virus titer was observed between the Wolbachia-positive and Wolbachia-cured groups.

CONCLUSIONS: These findings suggest that other mechanisms are involved in virus suppression within bed bugs, independent of the influence of Wolbachia, and our conclusions underscore the need for future research.

RevDate: 2019-09-10

Zheng B, Chen LH, QW Sun (2019)

Analyzing the control of dengue by releasing Wolbachia-infected male mosquitoes through a delay differential equation model.

Mathematical biosciences and engineering : MBE, 16(5):5531-5550.

To date, an innovative strategy to control dengue is to release Wolbachia-infected male mosquitoes into wild areas to sterilize wild female mosquito vectors by cytoplasmic incompatibility (CI). To investigate the efficacy of Wolbachia in blocking dengue virus transmission, we develop a deterministic mathematical model of human and mosquito populations in which one dengue serotype circulates. The delay differential equation model captures the respective extrinsic and intrinsic incu-bation periods (EIP and IIP) in the mosquito and human, as well as the maturation delay between mating and emergence of adult mosquitoes, which have received relatively little attention. We analyze the existence and stability of disease-free equilibria, and obtain a sufficient and necessary condition on the existence of the disease-endemic equilibrium. We also determine two threshold values of the release ratio $\theta$, denoted by $\theta_1^*$ and $\theta_2^*$ with $\theta_1^*>\theta_2^*$. When $\theta>\theta_1^*$, the mosquito population will be eradicated eventually. When $\theta_2^*<\theta < \theta_1^*$, a complete mosquito eradication becomes impossible, but virus eradication is ensured at the meantime. When $\theta<\theta_2^*$, the disease-endemic equilibrium emerges that allows dengue virus to circulate between humans and mosquitoes. We carry out sensitivity analysis of the threshold values in terms of the model parameters, and simulate several possible control strate-gies with different release ratios, which confirm the public awareness that reducing mosquito bites and killing adult mosquitoes are the most effective strategy to control the epidemic. Our model provides new insights on the effectiveness of Wolbachia in reducing dengue at a population level.

RevDate: 2019-09-10

Huang MG, Tang MX, Yu JS, et al (2019)

The impact of mating competitiveness and incomplete cytoplasmic incompatibility on Wolbachia-driven mosquito population suppressio.

Mathematical biosciences and engineering : MBE, 16(5):4741-4757.

To control mosquito-borne diseases such as dengue, malaria, and Zika, {\it Wolbachia}-infected male mosquitoes have been released in open areas to suppress wild mosquito population driven by cytoplasmic incompatibility (CI). In this work, we initiate a preliminary assessment on how the CI intensity $\xi$, and the mating competitiveness $\mu$ of released males relative to wild males, impact the suppression efficacy by a delay differential equation model. Our analysis identifies a threshold CI intensity $\xi_0\in (0, 1)$ as an increasing function of the natural reproduction rate of the wild mosquitoes, and a threshold value $r^*$ for the ratio $r(t)$ between the numbers of released males and wild males. The population suppression fails when $\xi\le \xi_0$, and succeeds when $\xi>\xi_0$ and $r(t)\ge r^*$. Our analyses indicate that $\xi$ plays a more important role than $\mu$ in the population suppression. For instance, a slight decrease of $\xi$ from 1 to 0.92 is more devastating than halving $\mu$ from 1 to 0.5. In our estimation of the optimal starting date for infected male release to target a more than $95\%$ wild population reduction during the peak season of dengue in Guangzhou, we find that the optimal date is almost independent of $\mu$ but is sensitive to $\xi$. If CI is complete, then starting about two months ahead can be an optimal option for less financial and labor costs. A slight reduction in the CI intensity requires a considerably earlier starting date.

RevDate: 2019-09-10

Liu YF, Sun GW, Wang L, et al (2019)

Establishing Wolbachia in the wild mosquito population: The effects of wind and critical patch size.

Mathematical biosciences and engineering : MBE, 16(5):4399-4414.

Releasing mosquitoes with Wolbachia into the wild mosquito population is becoming the very promising strategy to control mosquito-borne infections. To investigate the effects of wind and critical patch size on the Wolbachia establishment in the wild mosquito population, in this paper, we propose a diffusion-reaction-advection system in a heterogeneous environment. By studying the related eigenvalue problems, we derive various conditions under which Wolbachia can fully establish in the entire wild mosquito population. Our findings may provide some useful insights on designing practical releasing strategies to control the mosquito population.

RevDate: 2019-09-09

Ning SF, Zhou JC, Liu QQ, et al (2019)

Gradual, temperature-induced change of secondary sexual characteristics in Trichogramma pretiosum infected with parthenogenesis-inducing Wolbachia.

PeerJ, 7:e7567 pii:7567.

Intersex is an intermediate stage of sexual differentiation in insects. Determining intersex morphology and the cause of its production will aid in the understanding of the mechanism of sexual differentiation in insects. In this paper, Wolbachia-infected Trichogramma pretiosum (T. preW+) that shows thelytokous parthenogenesis were used as subjects. In order to determine the causes of the T. preW+ intersex and the influence of parental generation temperature on gradual changes in secondary masculinization in intersex offspring, we examined the occurrence of intersex offspring (F1 and F2 generation) after the parental generations were treated with high temperature (27, 29, 31, and 33 °C) and described the external morphology of the intersexes. The results showed that the T. preW+ parental generation temperature is positively correlated with the probability of intersex offspring. The probability of F1 intersex is significantly higher than that of F2 intersex in different high temperature. The degree of secondary masculinization in T. preW+ intersexes increases as parental generation temperature increases. In addition, our study first identified 11 intersex types in T. preW+ and found that the primary and secondary sexual characteristics showed a regular distribution. We also found that the D type and H type of intersex have the highest frequency of appearance. The external genitalia of most intersexes were female, and only three intersex types have male external genitalia. Conclusions were ultimately obtained: Wolbachia is a direct factor that causes the occurrence of intersexes, while high temperature is an indirect factor that determines the external morphology of intersexes. The effects of high temperature on T. preW+ intersexes is passed through the parental generation to offspring, and this maternal effect weakens as the number of generations increases. In T. preW+ intersex individuals, most exhibit female primary sexual characteristics, and secondary sexual characteristics exhibit signs of masculinization.

RevDate: 2019-09-09

Wan Sulaiman WA, Kamtchum-Tatuene J, Mohamed MH, et al (2019)

Anti-Wolbachia therapy for onchocerciasis & lymphatic filariasis: Current perspectives.

The Indian journal of medical research, 149(6):706-714.

Onchocerciasis and lymphatic filariasis (LF) are human filarial diseases belonging to the group of neglected tropical diseases, leading to permanent and long-term disability in infected individuals in the endemic countries such as Africa and India. Microfilaricidal drugs such as ivermectin and albendazole have been used as the standard therapy in filariasis, although their efficacy in eliminating the diseases is not fully established. Anti-Wolbachia therapy employs antibiotics and is a promising approach showing potent macrofilaricidal activity and also prevents embryogenesis. This has translated to clinical benefits resulting in successful eradication of microfilarial burden, thus averting the risk of adverse events from target species as well as those due to co-infection with loiasis. Doxycycline shows potential as an anti-Wolbachia treatment, leading to the death of adult parasitic worms. It is readily available, cheap and safe to use in adult non-pregnant patients. Besides doxycycline, several other potential antibiotics are also being investigated for the treatment of LF and onchocerciasis. This review aims to discuss and summarise recent developments in the use of anti-Wolbachia drugs to treat onchocerciasis and LF.

RevDate: 2019-09-09

O'Reilly KM, Hendrickx E, Kharisma DD, et al (2019)

Estimating the burden of dengue and the impact of release of wMel Wolbachia-infected mosquitoes in Indonesia: a modelling study.

BMC medicine, 17(1):172 pii:10.1186/s12916-019-1396-4.

BACKGROUND: Wolbachia-infected mosquitoes reduce dengue virus transmission, and city-wide releases in Yogyakarta city, Indonesia, are showing promising entomological results. Accurate estimates of the burden of dengue, its spatial distribution and the potential impact of Wolbachia are critical in guiding funder and government decisions on its future wider use.

METHODS: Here, we combine multiple modelling methods for burden estimation to predict national case burden disaggregated by severity and map the distribution of burden across the country using three separate data sources. An ensemble of transmission models then predicts the estimated reduction in dengue transmission following a nationwide roll-out of wMel Wolbachia.

RESULTS: We estimate that 7.8 million (95% uncertainty interval [UI] 1.8-17.7 million) symptomatic dengue cases occurred in Indonesia in 2015 and were associated with 332,865 (UI 94,175-754,203) lost disability-adjusted life years (DALYs). The majority of dengue's burden was due to non-severe cases that did not seek treatment or were challenging to diagnose in outpatient settings leading to substantial underreporting. Estimated burden was highly concentrated in a small number of large cities with 90% of dengue cases occurring in 15.3% of land area. Implementing a nationwide Wolbachia population replacement programme was estimated to avert 86.2% (UI 36.2-99.9%) of cases over a long-term average.

CONCLUSIONS: These results suggest interventions targeted to the highest burden cities can have a disproportionate impact on dengue burden. Area-wide interventions, such as Wolbachia, that are deployed based on the area covered could protect people more efficiently than individual-based interventions, such as vaccines, in such dense environments.

RevDate: 2019-09-06

Zheng Y, Shen W, Bi J, et al (2019)

Small RNA analysis provides new insights into cytoplasmic incompatibility in Drosophila melanogaster induced by Wolbachia.

Journal of insect physiology pii:S0022-1910(19)30148-9 [Epub ahead of print].

Wolbachia is a genus of endosymbiotic bacteria that induce a wide range of effects on their insect hosts. Cytoplasmic incompatibility (CI) is the most common phenotype mediated by Wolbachia and results in embryonic lethality when Wolbachia-infected males mate with uninfected females. Studies have revealed that bacteria can regulate many cellular processes in their hosts using small non-coding RNAs, so we investigated the involvement of small RNAs (sRNAs) in CI. Comparison of sRNA libraries between Wolbachia-infected and uninfected Drosophila melanogaster testes revealed 18 novel microRNAs (miRNAs), of which 12 were expressed specifically in Wolbachia-infected flies and one specifically in Wolbachia-uninfected flies. Furthermore, ten miRNAs showed differential expression, with four upregulated and six downregulated in Wolbachia-infected flies. Of the upregulated miRNAs, nov-miR-12 exhibited the highest upregulation in the testes of D. melanogaster. We then identified pipsqueak (psq) as the target gene of nov-miR-12 with the greatest complementarity in its 3' untranslated region (UTR). Wolbachia infection was correlated with reduced psq expression in D. melanogaster, and luciferase assays demonstrated that nov-miR-12 could downregulate psq through binding to its 3'UTR region. Knockdown of psq in Wolbachia-free fly testes significantly reduced egg hatching rate and mimicked the cellular abnormalities of Wolbachia-induced CI in embryos, including asynchronous nuclear division, chromatin bridging, and chromatin fragmentation. These results suggest that Wolbachia may induce CI in insect hosts by miRNA-mediated changes in host gene expression. Moreover, these findings reveal a potential molecular strategy for elucidating the complex interactions between endosymbionts and their insect hosts, such as Wolbachia-driven CI.

RevDate: 2019-09-06

Rohde BB, Staunton KM, Zeak NC, et al (2019)

Waterproof, low-cost, long-battery-life sound trap for surveillance of male Aedes aegypti for rear-and-release mosquito control programmes.

Parasites & vectors, 12(1):417 pii:10.1186/s13071-019-3647-9.

BACKGROUND: Sterile male rear-and-release programmes are of growing interest for controlling Aedes aegypti, including use an "incompatible insect technique" (IIT) to suppress transmission of dengue, Zika, and other viruses. Under IIT, males infected with Wolbachia are released into the suppression area to induce cytoplasmic incompatibility in uninfected populations. These and similar mosquito-release programmes require cost-effective field surveys of both sexes to optimize the locations, timing, and quantity of releases. Unfortunately, traps that sample male Ae. aegypti effectively are expensive and usually require mains power. Recently, an electronic lure was developed that attracts males using a 484 Hz sinusoidal tone mimicking the female wingbeat frequencies, broadcast in a 120 s on/off cycle. When deployed in commercially available gravid Aedes traps (GATs), the new combination, sound-GAT (SGAT), captures both males and females effectively. Given its success, there is interest in optimizing SGAT to reduce cost and power usage while maximizing catch rates.

METHODS: Options considered in this study included use of a smaller, lower-power microcontroller (Tiny) with either the original or a lower-cost speaker (lcS). A 30 s on/off cycle was tested in addition to the original 120 s cycle to minimize the potential that the longer cycle induced habituation. The original SGAT was compared against other traps incorporating the Tiny-based lures for mosquito capture in a large semi-field cage. The catch rates in waterproofed versions of this trap were then compared with catch rates in standard [BG-Sentinel 2 (BGS 2); Biogents AG, Regensburg, Germany] traps during an IIT field study in the Innisfail region of Queensland, Australia in 2017.

RESULTS: The system with a low-power microcontroller and low-cost speaker playing a 30 s tone (Tiny-lcS-30s) caught the highest proportion of males. The mean proportions of males caught in a semi-field cage were not significantly different among the original design and the four low-power, low-cost versions of the SGAT. During the IIT field study, the waterproofed version of the highest-rated, Tiny-lcS-30s SGAT captured male Ae. aegypti at similar rates as co-located BGS-2 traps.

CONCLUSIONS: Power- and cost-optimized, waterproofed versions of male Ae. aegypti acoustic lures in GATs are now available for field use in areas with sterile male mosquito rear-and-release programmes.

RevDate: 2019-09-04

Christensen S, Camacho M, Sharmin Z, et al (2019)

Quantitative methods for assessing local and bodywide contributions to Wolbachia titer in maternal germline cells of Drosophila.

BMC microbiology, 19(1):206 pii:10.1186/s12866-019-1579-3.

BACKGROUND: Little is known about how bacterial endosymbionts colonize host tissues. Because many insect endosymbionts are maternally transmitted, egg colonization is critical for endosymbiont success. Wolbachia bacteria, carried by approximately half of all insect species, provide an excellent model for characterizing endosymbiont infection dynamics. To date, technical limitations have precluded stepwise analysis of germline colonization by Wolbachia. It is not clear to what extent titer-altering effects are primarily mediated by growth rates of Wolbachia within cell lineages or migration of Wolbachia between cells.

RESULTS: The objective of this work is to inform mechanisms of germline colonization through use of optimized methodology. The approaches are framed in terms of nutritional impacts on Wolbachia. Yeast-rich diets in particular have been shown to suppress Wolbachia titer in the Drosophila melanogaster germline. To determine the extent of Wolbachia sensitivity to diet, we optimized 3-dimensional, multi-stage quantification of Wolbachia titer in maternal germline cells. Technical and statistical validation confirmed the identity of Wolbachia in vivo, the reproducibility of Wolbachia quantification and the statistical power to detect these effects. The data from adult feeding experiments demonstrated that germline Wolbachia titer is distinctly sensitive to yeast-rich host diets in late oogenesis. To investigate the physiological basis for these nutritional impacts, we optimized methodology for absolute Wolbachia quantification by real-time qPCR. We found that yeast-rich diets exerted no significant effect on bodywide Wolbachia titer, although ovarian titers were significantly reduced. This suggests that host diets affects Wolbachia distribution between the soma and late stage germline cells. Notably, relative qPCR methods distorted apparent wsp abundance, due to altered host DNA copy number in yeast-rich conditions. This highlights the importance of absolute quantification data for testing mechanistic hypotheses.

CONCLUSIONS: We demonstrate that absolute quantification of Wolbachia, using well-controlled cytological and qPCR-based methods, creates new opportunities to determine how bacterial abundance within the germline relates to bacterial distribution within the body. This methodology can be applied to further test germline infection dynamics in response to chemical treatments, genetic conditions, new host/endosymbiont combinations, or potentially adapted to analyze other cell and tissue types.

RevDate: 2019-08-31

Li Y, Liu X, H Guo (2019)

Population Dynamics of Wolbachia in Laodelphax striatellus (Fallén) Under Successive Stress of Antibiotics.

Current microbiology pii:10.1007/s00284-019-01762-0 [Epub ahead of print].

Wolbachia are the most common symbionts in arthropods; antibiotic treatment for eliminating the symbionts from their host is necessary to investigate the functions. Tetracycline antibiotics are widely used to remove endosymbiont Wolbachia from insect hosts. However, very little has been known on the effects of tetracycline on population size of Wolbachia in small brown planthopper (SBPH), Laodelphax striatellus (Fallén), an important insect pest of rice in Asia. Here, we investigated the dynamics of Wolbachia population density in females and males of L. striatellus by real-time fluorescent quantitative PCR method. The Wolbachia density in females and males of L. striatellus all declined sharply after treatment with 2 mg/mL tetracycline for one generation, and continued to decrease to a level which could not be detected by both qPCR and diagnostic PCR after treated for another generation, then maintained at 0 in the following three generations with continuous antibiotic treatment. Wolbachia infection did not recover in L. striatellus after stopping tetracycline treatment for ten generations. This is the first report to precisely monitor the population dynamics of Wolbachia in L. striatellus during successive tetracycline treatment and after that. The results provide a useful method for evaluating the efficiency of artificial operation of endosymbionts.

RevDate: 2019-08-30

Jiménez NE, Gerdtzen ZP, Olivera-Nappa Á, et al (2019)

A systems biology approach for studying Wolbachia metabolism reveals points of interaction with its host in the context of arboviral infection.

PLoS neglected tropical diseases, 13(8):e0007678 pii:PNTD-D-19-00279 [Epub ahead of print].

Wolbachia are alpha-proteobacteria known to infect arthropods, which are of interest for disease control since they have been associated with improved resistance to viral infection. Although several genomes for different strains have been sequenced, there is little knowledge regarding the relationship between this bacterium and their hosts, particularly on their dependency for survival. Motivated by the potential applications on disease control, we developed genome-scale models of four Wolbachia strains known to infect arthropods: wAlbB (Aedes albopictus), wVitA (Nasonia vitripennis), wMel and wMelPop (Drosophila melanogaster). The obtained metabolic reconstructions exhibit a metabolism relying mainly on amino acids for energy production and biomass synthesis. A gap analysis was performed to detect metabolic candidates which could explain the endosymbiotic nature of this bacterium, finding that amino acids, requirements for ubiquinone precursors and provisioning of metabolites such as riboflavin could play a crucial role in this relationship. This work provides a systems biology perspective for studying the relationship of Wolbachia with its host and the development of new approaches for control of the spread of arboviral diseases. This approach, where metabolic gaps are key objects of study instead of just additions to complete a model, could be applied to other endosymbiotic bacteria of interest.

RevDate: 2019-09-01

Ayala D, Akone-Ella O, Rahola N, et al (2019)

Natural Wolbachia infections are common in the major malaria vectors in Central Africa.

Evolutionary applications, 12(8):1583-1594 pii:EVA12804.

During the last decade, the endosymbiont bacterium Wolbachia has emerged as a biological tool for vector disease control. However, for long time, it was believed that Wolbachia was absent in natural populations of Anopheles. The recent discovery that species within the Anopheles gambiae complex host Wolbachia in natural conditions has opened new opportunities for malaria control research in Africa. Here, we investigated the prevalence and diversity of Wolbachia infection in 25 African Anopheles species in Gabon (Central Africa). Our results revealed the presence of Wolbachia in 16 of these species, including the major malaria vectors in this area. The infection prevalence varied greatly among species, confirming that sample size is a key factor to detect the infection. Moreover, our sequencing and phylogenetic analyses showed the important diversity of Wolbachia strains that infect Anopheles. Co-evolutionary analysis unveiled patterns of Wolbachia transmission within some Anopheles species, suggesting that past independent acquisition events were followed by co-cladogenesis. The large diversity of Wolbachia strains that infect natural populations of Anopheles offers a promising opportunity to select suitable phenotypes for suppressing Plasmodium transmission and/or manipulating Anopheles reproduction, which in turn could be used to reduce the malaria burden in Africa.

RevDate: 2019-09-05

Shi C, Beller L, Deboutte W, et al (2019)

Stable distinct core eukaryotic viromes in different mosquito species from Guadeloupe, using single mosquito viral metagenomics.

Microbiome, 7(1):121 pii:10.1186/s40168-019-0734-2.

BACKGROUND: Mosquitoes are the most important invertebrate viral vectors in humans and harbor a high diversity of understudied viruses, which has been shown in many mosquito virome studies in recent years. These studies generally performed metagenomics sequencing on pools of mosquitoes, without assessment of the viral diversity in individual mosquitoes. To address this issue, we applied our optimized viral metagenomics protocol (NetoVIR) to compare the virome of single and pooled Aedes aegypti and Culex quinquefasciatus mosquitoes collected from different locations in Guadeloupe, in 2016 and 2017.

RESULTS: The total read number and viral reads proportion of samples containing a single mosquito have no significant difference compared with those of pools containing five mosquitoes, which proved the feasibility of using single mosquito for viral metagenomics. A comparative analysis of the virome revealed a higher abundance and more diverse eukaryotic virome in Aedes aegypti, whereas Culex quinquefasciatus harbors a richer and more diverse phageome. The majority of the identified eukaryotic viruses were mosquito-species specific. We further characterized the genomes of 11 novel eukaryotic viruses. Furthermore, qRT-PCR analyses of the six most abundant eukaryotic viruses indicated that the majority of individual mosquitoes were infected by several of the selected viruses with viral genome copies per mosquito ranging from 267 to 1.01 × 108 (median 7.5 × 106) for Ae. aegypti and 192 to 8.69 × 106 (median 4.87 × 104) for Cx. quinquefasciatus. Additionally, in Cx. quinquefasciatus, a number of phage contigs co-occurred with several marker genes of Wolbachia sp. strain wPip.

CONCLUSIONS: We firstly demonstrate the feasibility to use single mosquito for viral metagenomics, which can provide much more precise virome profiles of mosquito populations. Interspecific comparisons show striking differences in abundance and diversity between the viromes of Ae. aegypti and Cx. quinquefasciatus. Those two mosquito species seem to have their own relatively stable "core eukaryotic virome", which might have important implications for the competence to transmit important medically relevant arboviruses. The presence of Wolbachia in Cx. quinquefasciatus might explain (1) the lower overall viral load compared to Ae. aegypti, (2) the identification of multiple unknown phage contigs, and (3) the difference in competence for important human pathogens. How these viruses, phages, and bacteria influence the physiology and vector competence of mosquito hosts warrants further research.

RevDate: 2019-08-27

Ford SA, Allen SL, Ohm JR, et al (2019)

Selection on Aedes aegypti alters Wolbachia-mediated dengue virus blocking and fitness.

Nature microbiology pii:10.1038/s41564-019-0533-3 [Epub ahead of print].

The dengue, Zika and chikungunya viruses are transmitted by the mosquito Aedes aegypti and pose a substantial threat to global public health. Current vaccines and mosquito control strategies have limited efficacy, so novel interventions are needed1,2. Wolbachia are bacteria that inhabit insect cells and have been found to reduce viral infection-a phenotype that is referred to as viral 'blocking'3. Although not naturally found in A. aegypti4, Wolbachia were stably introduced into this mosquito in 20114,5 and were shown to reduce the transmission potential of dengue, Zika and chikungunya6,7. Subsequent field trials showed Wolbachia's ability to spread through A. aegypti populations and reduce the local incidence of dengue fever8. Despite these successes, the evolutionary stability of viral blocking is unknown. Here, we utilized artificial selection to reveal genetic variation in the mosquito that affects Wolbachia-mediated dengue blocking. We found that mosquitoes exhibiting weaker blocking also have reduced fitness, suggesting the potential for natural selection to maintain blocking. We also identified A. aegypti genes that affect blocking strength, shedding light on a possible mechanism for the trait. These results will inform the use of Wolbachia as biocontrol agents against mosquito-borne viruses and direct further research into measuring and improving their efficacy.

RevDate: 2019-09-04

Genchi M, Vismarra A, Lucchetti C, et al (2019)

Efficacy of imidacloprid 10%/moxidectin 2.5% spot on (Advocate®, Advantage Multi®) and doxycycline for the treatment of natural Dirofilaria immitis infections in dogs.

Veterinary parasitology, 273:11-16 pii:S0304-4017(19)30174-8 [Epub ahead of print].

Heartworm infection (also known as dirofilariosis due to Dirofilaria immitis) in dogs causes chronic pulmonary disease that, if left untreated, can lead to right-side congestive heart failure. Currently, the only registered drug for adulticide therapy in dogs with heartworm disease (HWD) is melarsomine dihydrochloride. The recent targeting of the bacterial endosymbiont Wolbachia, through antibiotic therapy of the infected host, has offered an interesting alternative for the treatment of HWD. Recent reports of the adulticide activity of an ivermectin/doxycycline combination protocol has lead the American Heartworm Society (AHS) to include in its guidelines that, in cases where arsenical therapy is not possible or is contraindicated, a monthly heartworm preventive along with doxycycline for a 4-week period might be considered. In the present study, 20 dogs with confirmed natural D. immitis infection were included following owner consent. Fourteen dogs were treated with a topical formulation containing 10% w/v imidacloprid and 2.5% w/v moxidectin (Advocate®, Advantage Multi®, Bayer), monthly for nine months, associated to doxycycline (10 mg/kg/BID) for the first 30 days. Six dogs were treated with melarsomine (Immiticide®, Merial) (2.5 mg/kg) at enrollment, followed one month later by two injections 24 h apart. The presence of circulating antigens and the number of microfilariae (mf) were evaluated at the moment of enrollment and then at 1, 2, 3, 4, 5, 6, 7, 8, 12, 18, 24 months post enrollment. Echocardiogram and radiographs were performed at month 0, 6, 12, 18, 24. Monthly moxidectin combined with 30 days of doxycycline eliminated circulating microfilariae within one month, thus breaking the transmission cycle very quickly. Furthermore, dogs treated with the combination protocol started to become negative for circulating antigens at 4 months from the beginning of treatment and all except one were antigen negative at 9 months. All dogs treated with melarsomine were antigen negative by 5 months from the beginning of the treatment. No dogs showed worsening of pulmonary patterns or criteria indicative of pulmonary hypertension 12 to 24 months after. For the criteria mf concentration, antigen concentration, radiography and echocardiography at 12, 18 and 24 months the non-inferiority for the moxidectin group could be proven for a non-inferiority margin of 15% for the rate difference. Dogs treated with moxidectin and doxycycline became negative for microfilariae and antigens sooner when compared to melarsomine in the present study and to dogs treated with doxycycline combined with ivermectin in studies previously published.

RevDate: 2019-08-23

Cohnstaedt LW, C Alfonso-Parra (2019)

2018 Highlights of Mosquito and Vector Biology and Control in Latin America.

Journal of the American Mosquito Control Association, 35(1):40-46.

The 28th Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 84th Annual Meeting of the AMCA held in Kansas City, MO, in February 2018. The Latin American Symposium promotes the participation of vector control specialists, public health workers, and academic members from Latin America and the sharing of scientific data between continents. Generally, presentations are in Spanish with simultaneous translation into English. The majority of presentation slides are in English to facilitate communication among all meeting attendees. This publication includes summaries of 14 oral presentations by participants from Colombia, Mexico, and the United States of America. Topics addressed in the 3 sessions of the symposium included: larval habitats, insecticide resistance, new Aedes mosquito traps, blood meal analysis and fitness outcomes, vertical transmission of dengue, and transstadial composition of midgut microbiota. Control techniques discussed included sterile insect technique (SIT) with radiation, SIT by Wolbachia, thermal fogging, ultra-low volume pesticide applications, indoor residual spraying, Bacillus thuringiensis israelensis de Barjac (Bti), and Spinosad larval treatments. Presentations were also given on species composition and diversity of phlebotomine sand flies. Presentations were related to the vector species belonging to the mosquito genera, Anopheles, Aedes, and Culex as well as phlebotomine sand flies involved in the transmission of the causal agents of malaria, arboviruses (dengue, chikungunya, Zika), and leishmaniasis.

RevDate: 2019-08-25

Bennett KL, Gómez-Martínez C, Chin Y, et al (2019)

Dynamics and diversity of bacteria associated with the disease vectors Aedes aegypti and Aedes albopictus.

Scientific reports, 9(1):12160 pii:10.1038/s41598-019-48414-8.

Aedes aegypti and Aedes albopictus develop in the same aquatic sites where they encounter microorganisms that influence their life history and capacity to transmit human arboviruses. Some bacteria such as Wolbachia are currently being considered for the control of Dengue, Chikungunya and Zika. Yet little is known about the dynamics and diversity of Aedes-associated bacteria, including larval habitat features that shape their tempo-spatial distribution. We applied large-scale 16S rRNA amplicon sequencing to 960 adults and larvae of both Ae. aegypti and Ae. albopictus mosquitoes from 59 sampling sites widely distributed across nine provinces of Panama. We find both species share a limited, yet highly variable core microbiota, reflecting high stochasticity within their oviposition habitats. Despite sharing a large proportion of microbiota, Ae. aegypti harbours higher bacterial diversity than Ae. albopictus, primarily due to rarer bacterial groups at the larval stage. We find significant differences between the bacterial communities of larvae and adult mosquitoes, and among samples from metal and ceramic containers. However, we find little support for geography, water temperature and pH as predictors of bacterial associates. We report a low incidence of natural Wolbachia infection for both Aedes and its geographical distribution. This baseline information provides a foundation for studies on the functions and interactions of Aedes-associated bacteria with consequences for bio-control within Panama.

RevDate: 2019-08-21

Charlesworth J, Weinert LA, Araujo EV, et al (2019)

Wolbachia, Cardinium and climate: an analysis of global data.

Biology letters, 15(8):20190273.

Bacterial endosymbionts are very common in terrestrial arthropods, but infection levels vary widely among populations. Experiments and within-species comparisons suggest that environmental temperature might be important in explaining this variation. To investigate the importance of temperature, at broad geographical and taxonomic scales, we extended a global database of terrestrial arthropods screened for Wolbachia and Cardinium. Our final dataset contained data from more than 117 000 arthropods (over 2500 species) screened for Wolbachia and more than 18 000 arthropods (over 800 species) screened for Cardinium, including samples from 137 different countries, with mean temperatures varying from -6.5 to 29.2°C. In insects and relatives, Cardinium infection showed a clear and consistent tendency to increase with temperature. For Wolbachia, a tendency to increase with temperature in temperate climates is counteracted by reduced prevalence in the tropics, resulting in a weak negative trend overall. We discuss the implications of these results for natural and introduced symbionts in regions affected by climate change.

RevDate: 2019-08-20

Mathé-Hubert H, Kaech H, Hertaeg C, et al (2019)

Non-random associations of maternally transmitted symbionts in insects: The roles of drift versus biased co-transmission and selection.

Molecular ecology [Epub ahead of print].

Virtually all higher organisms form holobionts with associated microbiota. To understand the biology of holobionts we need to know how species assemble and interact. Controlled experiments are suited to study interactions between particular symbionts, but they only accommodate a tiny portion of the diversity within each species. Alternatively, interactions can be inferred by testing if associations among symbionts in the field are more or less frequent than expected under random assortment. However, random assortment may not be a valid null hypothesis for maternally transmitted symbionts since drift alone can result in associations. Here we analyse a European field survey of endosymbionts in pea aphids (Acyrthosiphon pisum), confirming that symbiont associations are pervasive. To interpret them, we develop a model simulating the effect of drift on symbiont associations. We show that drift induces apparently non-random assortment, even though horizontal transmissions and maternal transmission failures tend to randomise symbiont associations. We also use this model in the approximate Bayesian computation framework to re-visit the association between Spiroplasma and Wolbachia in Drosophila neotestacea reported by Jaenike et al. (2010a). New field data reported here reveal that this association has disappeared in the investigated location, yet a significant interaction between Spiroplasma and Wolbachia can still be inferred. Our study confirms that negative and positive associations are pervasive and often induced by symbiont-symbiont interactions. Nevertheless, some associations are also likely to be driven by drift. This possibility needs to be considered when performing such analyses, and our model is helpful for this purpose. This article is protected by copyright. All rights reserved.

RevDate: 2019-09-01

Huang HJ, Cui JR, Chen J, et al (2019)

Proteomic analysis of Laodelphax striatellus gonads reveals proteins that may manipulate host reproduction by Wolbachia.

Insect biochemistry and molecular biology, 113:103211 pii:S0965-1748(19)30325-X [Epub ahead of print].

Wolbachia are intracellular bacteria that manipulate host reproduction by several mechanisms including cytoplasmic incompatibility (CI). However, the underlying mechanisms of Wolbachia-induced CI are not entirely clear. Here, we monitored the Wolbachia distribution in the male gonads of the small brown planthopper (Laodelphax striatellus, SBPH) at different development stages, and investigated the influence of Wolbachia on male gonads by a quantitative proteomic analysis. A total of 276 differentially expressed proteins were identified, with the majority of them participating in metabolism, modification, and reproduction. Knocking down the expression of outer dense fiber protein (ODFP) and venom allergen 5-like (VA5L) showed decreased egg reproduction, and these two genes might be responsible for Wolbachia improved fecundity in infected L. striatellus; whereas knocking down the expression of cytosol amino-peptidase-like (CAL) significantly decreased the egg hatch rate in Wolbachia-uninfected L. striatellus, but not in the Wolbachia-infected one. Considering that the mRNA/protein level of CAL was downregulated by Wolbachia infection and dsCAL treatment closely mimicked Wolbachia-induced CI, we presumed that CAL might be one of the factors determining the CI phenotype.

RevDate: 2019-08-29

Doremus MR, Kelly SE, MS Hunter (2019)

Exposure to opposing temperature extremes causes comparable effects on Cardinium density but contrasting effects on Cardinium-induced cytoplasmic incompatibility.

PLoS pathogens, 15(8):e1008022 pii:PPATHOGENS-D-19-00998.

Terrestrial arthropods, including insects, commonly harbor maternally inherited intracellular symbionts that confer benefits to the host or manipulate host reproduction to favor infected female progeny. These symbionts may be especially vulnerable to thermal stress, potentially leading to destabilization of the symbiosis and imposing costs to the host. For example, increased temperatures can reduce the density of a common reproductive manipulator, Wolbachia, and the strength of its crossing incompatibility (cytoplasmic incompatibility, or CI) phenotype. Another manipulative symbiont, Cardinium hertigii, infects ~ 6-10% of Arthropods, and also can induce CI, but there is little homology between the molecular mechanisms of CI induced by Cardinium and Wolbachia. Here we investigated whether temperature disrupts the CI phenotype of Cardinium in a parasitic wasp host, Encarsia suzannae. We examined the effects of both warm (32°C day/ 29°C night) and cool (20°C day/ 17°C night) temperatures on Cardinium CI and found that both types of temperature stress modified aspects of this symbiosis. Warm temperatures reduced symbiont density, pupal developmental time, vertical transmission rate, and the strength of both CI modification and rescue. Cool temperatures also reduced symbiont density, however this resulted in stronger CI, likely due to cool temperatures prolonging the host pupal stage. The opposing effects of cool and warm-mediated reductions in symbiont density on the resulting CI phenotype indicates that CI strength may be independent of density in this system. Temperature stress also modified the CI phenotype only if it occurred during the pupal stage, highlighting the likely importance of this stage for CI induction in this symbiosis.

RevDate: 2019-08-20

Lorenzo-Carballa MO, Torres-Cambas Y, Heaton K, et al (2019)

Widespread Wolbachia infection in an insular radiation of damselflies (Odonata, Coenagrionidae).

Scientific reports, 9(1):11933 pii:10.1038/s41598-019-47954-3.

Wolbachia is one of the most common endosymbionts found infecting arthropods. Theory predicts symbionts like Wolbachia will be more common in species radiations, as host shift events occur with greatest frequency between closely related species. Further, the presence of Wolbachia itself may engender reproductive isolation, and promote speciation of their hosts. Here we screened 178 individuals belonging to 30 species of the damselfly genera Nesobasis and Melanesobasis - species radiations endemic to the Fiji archipelago in the South Pacific - for Wolbachia, using multilocus sequence typing to characterize bacterial strains. Incidence of Wolbachia was 71% in Nesobasis and 40% in Melanesobasis, and prevalence was also high, with an average of 88% in the Nesobasis species screened. We identified a total of 25 Wolbachia strains, belonging to supergroups A, B and F, with some epidemic strains present in multiple species. The occurrence of Wolbachia in both males and females, and the similar global prevalence found in both sexes rules out any strong effect of Wolbachia on the primary sex-ratio, but are compatible with the phenotype of cytoplasmic incompatibility. Nesobasis has higher species richness than most endemic island damselfly genera, and we discuss the potential for endosymbiont-mediated speciation within this group.

RevDate: 2019-08-20

Gonçalves DDS, Hooker DJ, Dong Y, et al (2019)

Detecting wMel Wolbachia in field-collected Aedes aegypti mosquitoes using loop-mediated isothermal amplification (LAMP).

Parasites & vectors, 12(1):404 pii:10.1186/s13071-019-3666-6.

BACKGROUND: The World Mosquito Program uses Wolbachia pipientis for the biocontrol of arboviruses transmitted by Aedes aegypti mosquitoes. Diagnostic testing for Wolbachia in laboratory colonies and in field-caught mosquito populations has typically employed PCR. New, simpler methods to diagnose Wolbachia infection in mosquitoes are required for large-scale operational use.

METHODS: Field-collected Ae. aegypti mosquitoes from North Queensland were tested using primers designed to detect the Wolbachia wsp gene, specific to the strain wMel. The results were analysed by colour change in the reaction mix. Furthermore, to confirm the efficiency of the LAMP assay, the results were compared to the gold-standard qPCR test.

RESULTS: A novel loop-mediated isothermal amplification (LAMP) colorimetric test for the wMel strain of Wolbachia was designed, developed and validated for use in a high-throughput setting. Against the standard qPCR test, the analytical sensitivity, specificity and diagnostic metrics were: sensitivity (99.6%), specificity (92.2%), positive predictive value (97.08%) and negative predictive value (99.30%).

CONCLUSIONS: We describe an alternative, novel and high-throughput method for diagnosing wMel Wolbachia infections in mosquitoes. This assay should support Wolbachia surveillance in both laboratory and field populations of Ae. aegypti.

RevDate: 2019-08-14

Zhu YX, Song ZR, Song YL, et al (2019)

The microbiota in spider mite faeces potentially reflects intestinal bacterial communities in the host.

Insect science [Epub ahead of print].

Microorganisms provide many physiological functions to herbivorous hosts. Spider mites (genus Tetranychus) are important agricultural pests throughout the world, however, the composition of spider mite microbial community, especially gut microbiome, remains unclear. Here, we investigated the bacterial community in five spider mite species and their associated faeces by deep sequencing of the 16S rRNA gene. The composition of the bacterial community was significantly different among the five prevalent spider mite species, and some bacterial symbionts showed host-species specificity. Moreover, the abundance of the bacterial community in spider mite faeces was significantly higher than that in the corresponding spider mite samples. However, Flavobacterium was detected in all samples, and represent a "core microbiome". Remarkably, the maternally inherited endosymbiont Wolbachia was detected in both spider mite and faeces. Overall, these results offer insight into the complex community of symbionts in spider mites, and give a new direction for future studies. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-18

Lucchetti C, Genchi M, Venco L, et al (2019)

Differential ABC transporter gene expression in adult Dirofilaria immitis males and females following in vitro treatment with ivermectin, doxycycline or a combination of both.

Parasites & vectors, 12(1):401 pii:10.1186/s13071-019-3645-y.

BACKGROUND: Combination doxycycline/macrocyclic lactone (ML) protocols have been shown to provide a more rapid adulticidal and microfilaricidal effect than either MLs or doxycycline alone, although female worms were reported to have a higher tolerance to treatments compared to male worms. The present study aimed to evaluate how ABC transporters may be involved in the synergic effect of the combination treatment. Adult worms of D. immitis were treated in vitro for 24 hours with doxycycline (DOXY), ivermectin (IVM) and a combination of both, and changes in the modulation of ABC transporter genes were measured. Levels of doxycycline inside different treatment media, post-treatment, were determined through HPLC analysis.

RESULTS: Quantitative RT-PCR analysis showed the presence of changes in the modulation of ABC transporter genes evaluated in this study. In particular, in female worms, the combination treatment induced a substantial increase in gene expressions, especially of Dim-pgp-10 and Dim-haf-4; whereas in male worms, the greatest increase in gene expression was observed for Dim-pgp-10 and Dim-pgp-11 when treated with DMSO + IVM and DMSO + DOXY/IVM. HPLC analysis of the DOXY concentrations in the media after in vitro treatments of male worms showed a slight difference between the DMSO + DOXY samples and the combination (DMSO + DOXY + IVM), while no difference was observed among females.

CONCLUSIONS: Further studies are required to explain whether the modulation of cellular efflux plays a role, even partially, in the adulticide effect of doxycycline/macrocyclic lactone combinations in heartworm-infected dogs. To the authors' knowledge, this is the first study to evaluate P-gp expression in adult D. immitis.

RevDate: 2019-08-13

Bockoven AA, Bondy EC, Flores MJ, et al (2019)

What Goes Up Might Come Down: the Spectacular Spread of an Endosymbiont Is Followed by Its Decline a Decade Later.

Microbial ecology pii:10.1007/s00248-019-01417-4 [Epub ahead of print].

Facultative, intracellular bacterial symbionts of arthropods may dramatically affect host biology and reproduction. The length of these symbiont-host associations may be thousands to millions of years, and while symbiont loss is predicted, there have been very few observations of a decline of symbiont infection rates. In a population of the sweet potato whitefly species (Bemisia tabaci MEAM1) in Arizona, USA, we documented the frequency decline of a strain of Rickettsia in the Rickettsia bellii clade from near-fixation in 2011 to 36% of whiteflies infected in 2017. In previous studies, Rickettsia had been shown to increase from 1 to 97% from 2000 to 2006 and remained at high frequency for at least five years. At that time, Rickettsia infection was associated with both fitness benefits and female bias. In the current study, we established matrilines of whiteflies from the field (2016, Rickettsia infection frequency = 58%) and studied (a) Rickettsia vertical transmission, (b) fitness and sex ratios associated with Rickettsia infection, (c) symbiont titer, and (d) bacterial communities within whiteflies. The vertical transmission rate was high, approximately 98%. Rickettsia infection in the matrilines was not associated with fitness benefits or sex ratio bias and appeared to be slightly costly, as more Rickettsia-infected individuals produced non-hatching eggs. Overall, the titer of Rickettsia in the matrilines was lower in 2016 than in the whiteflies collected in 2011, but the titer distribution appeared bimodal, with high- and low-titer lines, and constancy of the average titer within lines over three generations. We found neither association between Rickettsia titer and fitness benefits or sex ratio bias nor evidence that Rickettsia was replaced by another secondary symbiont. The change in the interaction between symbiont and host in 2016 whiteflies may explain the drop in symbiont frequency we observed.

RevDate: 2019-08-09

Anderson ML, Rustin RC, ME Eremeeva (2019)

Pilot survey of mosquitoes (Diptera: Culicidae) from southeastern Georgia, USA for Wolbachia and Rickettsia felis (Rickettsiales: Rickettsiaceae).

Journal of vector borne diseases, 56(2):92-97.

Background & objectives: Mosquito surveillance is one of the critical functions of local health departments, particularly in the context of outbreaks of severe mosquito-borne viral infections. Unfortunately, some viral and parasitic infections transmitted by mosquitoes, manifests non-specific clinical symptoms which may actually be of rickettsial etiology, including Rickettsia felis infections. This study tested the hypothesis that mosquitoes from southeastern Georgia, USA may be infected with Rickettsia felis and Wolbachia, an endosymbiotic bacterium of the order Rickettsiales.

Methods: Specimens of the five most common mosquito species occurring in the region were collected using gravid and light-traps and identified using morphological keys. Mosquitoes were then pooled by species, sex, trap and collection site and their DNA was extracted. Molecular methods were used to confirm mosquito identification, and presence of Wolbachia and R. felis.

Results: Wolbachia DNA was detected in 90.8% of the mosquito pools tested, which included 98% pools of Cx. quinquefasciatus Say (Diptera: Culicidae), 95% pools of Ae. albopictus Skuse (Diptera: Culicidae), and 66.7% of pools of Cx. pipiens complex. Samples of An. punctipennis Say (Diptera: Culicidae) and An. crucians Wiedemann (Diptera: Culicidae) were tested negative for Wolbachia DNA. Three genotypes of Wolbachia sp. belonging to Group A (1 type) and Group B (2 types) were identified. DNA of R. felis was not found in any pool of mosquitoes tested.

This study provides a pilot data on the high presence of Wolbachia in Cx. quinque-fasciatus and Ae. albopictus mosquitoes prevalent in the study region. Whether the high prevalence of Wolbachia and its genetic diversity in mosquitoes affects the mosquitoes' susceptibility to R. felis infection in Georgia will need further evaluation.

RevDate: 2019-08-11

Liu L, Zhang KJ, Rong X, et al (2019)

Identification of Wolbachia-Responsive miRNAs in the Small Brown Planthopper, Laodelphax striatellus.

Frontiers in physiology, 10:928.

Laodelphax striatellus is naturally infected with the Wolbachia strain wStri, which induces strong cytoplasmic incompatibility of its host. MicroRNAs (miRNAs) are a class of endogenous non-coding small RNAs that play a critical role in the regulation of gene expression at post-transcriptional level in various biological processes. Despite various studies reporting that Wolbachia affects the miRNA expression of their hosts, the molecular mechanism underlying interactions between Wolbachia and their host miRNAs has not been well understood. In order to better understand the impact of Wolbachia infection on its host, we investigated the differentially expressed miRNAs between Wolbachia-infected and Wolbachia-uninfected strains of L. striatellus. Compared with uninfected strains, Wolbachia infection resulted in up-regulation of 18 miRNAs and down-regulation of 6 miRNAs in male, while 25 miRNAs were up-regulated and 15 miRNAs were down-regulated in female. The target genes of these differentially expressed miRNAs involved in immune response regulation, reproduction, redox homeostasis and ecdysteroidogenesis were also annotated in both sexes. We further verified the expression of several significantly differentially expressed miRNAs and their predicted target genes by qRT-PCR method. The results suggested that Wolbachia appears to reduce the expression of genes related to fertility in males and increase the expression of genes related to fecundity in females. At the same time, Wolbachia may enhance the expression of immune-related genes in both sexes. All of the results in this study may be helpful in further exploration of the molecular mechanisms by which Wolbachia affects on its hosts.

RevDate: 2019-08-06

Klinges JG, Rosales SM, McMinds R, et al (2019)

Phylogenetic, genomic, and biogeographic characterization of a novel and ubiquitous marine invertebrate-associated Rickettsiales parasite, Candidatus Aquarickettsia rohweri, gen. nov., sp. nov.

The ISME journal pii:10.1038/s41396-019-0482-0 [Epub ahead of print].

Bacterial symbionts are integral to the health and homeostasis of invertebrate hosts. Notably, members of the Rickettsiales genus Wolbachia influence several aspects of the fitness and evolution of their terrestrial hosts, but few analogous partnerships have been found in marine systems. We report here the genome, phylogenetics, and biogeography of a ubiquitous and novel Rickettsiales species that primarily associates with marine organisms. We previously showed that this bacterium was found in scleractinian corals, responds to nutrient exposure, and is associated with reduced host growth and increased mortality. This bacterium, like other Rickettsiales, has a reduced genome indicative of a parasitic lifestyle. Phylogenetic analysis places this Rickettsiales within a new genus we define as "Candidatus Aquarickettsia." Using data from the Earth Microbiome Project and SRA databases, we also demonstrate that members of "Ca. Aquarickettsia" are found globally in dozens of invertebrate lineages. The coral-associated "Candidatus A. rohweri" is the first complete genome in this new clade. "Ca. A. rohweri" lacks genes to synthesize most sugars and amino acids but possesses several genes linked to pathogenicity including Tlc, an antiporter that exchanges host ATP for ADP, and a complete Type IV secretion system. Despite its inability to metabolize nitrogen, "Ca. A. rohweri" possesses the NtrY-NtrX two-component system involved in sensing and responding to extracellular nitrogen. Given these data, along with visualization of the parasite in host tissues, we hypothesize that "Ca. A. rohweri" reduces coral health by consuming host nutrients and energy, thus weakening and eventually killing host cells. Last, we hypothesize that nutrient enrichment, which is increasingly common on coral reefs, encourages unrestricted growth of "Ca. A. rohweri" in its host by providing abundant N-rich metabolites to be scavenged.

RevDate: 2019-08-18

Hübner MP, Koschel M, Struever D, et al (2019)

In vivo kinetics of Wolbachia depletion by ABBV-4083 in L. sigmodontis adult worms and microfilariae.

PLoS neglected tropical diseases, 13(8):e0007636 pii:PNTD-D-19-00664.

Depletion of Wolbachia endosymbionts of human pathogenic filariae using 4-6 weeks of doxycycline treatment can lead to permanent sterilization and adult filarial death. We investigated the anti-Wolbachia drug candidate ABBV-4083 in the Litomosoides sigmodontis rodent model to determine Wolbachia depletion kinetics with different regimens. Wolbachia reduction occurred in mice as early as 3 days after the initiation of ABBV-4083 treatment and continued throughout a 10-day treatment period. Importantly, Wolbachia levels continued to decline after a 5-day-treatment from 91.5% to 99.9% during a 3-week washout period. In jirds, two weeks of ABBV-4083 treatment (100mg/kg once-per-day) caused a >99.9% Wolbachia depletion in female adult worms, and the kinetics of Wolbachia depletion were recapitulated in peripheral blood microfilariae. Similar to Wolbachia depletion, inhibition of embryogenesis was time-dependent in ABBV-4083-treated jirds, leading to a complete lack of late embryonic stages (stretched microfilariae) and lack of peripheral microfilariae in 5/6 ABBV-4083-treated jirds by 14 weeks after treatment. Twice daily treatment in comparison to once daily treatment with ABBV-4083 did not significantly improve Wolbachia depletion. Moreover, up to 4 nonconsecutive daily treatments within a 14-dose regimen did not significantly erode Wolbachia depletion. Within the limitations of an animal model that does not fully recapitulate human filarial disease, our studies suggest that Wolbachia depletion should be assessed clinically no earlier than 3-4 weeks after the end of treatment, and that Wolbachia depletion in microfilariae may be a viable surrogate marker for the depletion within adult worms. Furthermore, strict daily adherence to the dosing regimen with anti-Wolbachia candidates may not be required, provided that the full regimen is subsequently completed.

RevDate: 2019-08-08

Yoshida K, Sanada-Morimura S, Huang SH, et al (2019)

Influences of two coexisting endosymbionts, CI-inducing Wolbachia and male-killing Spiroplasma, on the performance of their host Laodelphax striatellus (Hemiptera: Delphacidae).

Ecology and evolution, 9(14):8214-8224 pii:ECE35392.

The small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae) is reported to have the endosymbiont Wolbachia, which shows a strong cytoplasmic incompatibility (CI) between infected males and uninfected females. In the 2000s, female-biased L. striatellus populations were found in Taiwan, and this sex ratio distortion was the result of male-killing induced by the infection of another endosymbiont, Spiroplasma. Spiroplasma infection is considered to negatively affect both L. striatellus and Wolbachia because the male-killing halves the offspring of L. striatellus and hinders the spread of Wolbachia infection via CI. Spiroplasma could have traits that increase the fitness of infected L. striatellus and/or coexisting organisms because the coinfection rates of Wolbachia and Spiroplasma were rather high in some areas. In this study, we investigated the influences of the infection of these two endosymbionts on the development, reproduction, and insecticide resistance of L. striatellus in the laboratory. Our results show that the single-infection state of Spiroplasma had a negative influence on the fertility of L. striatellus, while the double-infection state had no significant influence. At late nymphal and adult stages, the abundance of Spiroplasma was lower in the double-infection state than in the single-infection state. In the double-infection state, the reduction of Spiroplasma density may be caused by competition between the two endosymbionts, and the negative influence of Spiroplasma on the fertility of host may be relieved. The resistance of L. striatellus to four insecticides was compared among different infection states of endosymbionts, but Spiroplasma infection did not contribute to increase insecticide resistance. Because positive influences of Spiroplasma infection were not found in terms of the development, reproduction, and insecticide resistance of L. striatellus, other factors improving the fitness of Spiroplasma-infected L. striatellus may be related to the high frequency of double infection in some L. striatellus populations.

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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.

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