Biology subjects

Sinkins, S. P.

Publications and source records attributed to Sinkins, S. P..

14 recordsLinked to original sources

bioRxiv2026

Evolutionary genomics of a natural Wolbachia superinfection in the dengue mosquito Aedes albopictus

Aedes albopictus, an invasive mosquito vector of human pathogens, is naturally infected by two strains of the endosymbiotic bacterium Wolbachia, wAlbA and wAlbB. Here, we present a comprehensive genomic analysis of these Wolbachia strains, their associated plasmids, and host mitochondrial DNA (mtDNA). We observed extensive variation in Wolbachia densities--spanning over three orders of magnitude--indicating that infections often exist at extremely low levels and this variation is largely driven by environmental factors. Phylogenetic analyses revealed concordant evolutionary histories among mitochondrial, Wolbachia, and plasmid genomes, with no strong evidence for horizontal or paternal transmission. We estimate that the common ancestor of the superinfection existed [~]6,000--9,000 years ago. Patterns of genetic structure and divergence indicate that the subsequent geographical spread of Wolbachia has mirrored host population history. Comparative rate analyses revealed that wAlbA evolves more slowly than wAlbB, consistent with a reduced mutation rate. Despite the close relationship between wAlbB lineages, gene content in this strain is highly variable, with 184 genes exhibiting presence-absence or copy number variation across strains, including genes involved in inducing cytoplasmic incompatibility. Several of these genes reside in repetitive or prophage regions, indicating that transposable elements appear to drive structural genomic variation in Wolbachia populations. Together, our results highlight extensive natural diversity within Wolbachia populations and provide a foundation for understanding symbiont dynamics in nature and to inform the selection of strains for Wolbachia-based vector control programs.

evolutionary biology↗

bioRxiv2026

Telomere-to-telomere genome assembly of Microsporidia sp. MB, a microsporidian symbiont of Anopheles coluzzii isolated from Burkina Faso

BackgroundMicrosporidia sp. MB is an intracellular parasite of anopheline mosquitoes identified across the African continent. Microsporidia sp. MB infections appear to have no significant effect on host fitness and vertically transmit, whilst infected individuals have exhibited significantly reduced levels of Plasmodium falciparum transmission. These combined characteristics make Microsporidia sp. MB a promising candidate for use in malaria control. A comprehensive genome would greatly facilitate investigation into the evolution and biological pathways underlying important phenotypes, such as the mechanism of malarial inhibition. ResultsIn this study, we present the de novo assembly of the first complete genome of Microsporidia sp. MB SOUVK7. Multi-platform sequencing was performed on ovary samples of laboratory established Anopheles coluzzii collected from Burkina Faso. The SOUVK7 genome has a total size of 9.16Mb, encodes 2,435 genes and is organised into 13 chromosomes with telomeres identified at all flanks. Telomeric repeats exhibit a 4-mer motif due to a glutamine deletion previously unobserved in Microsporidia. Ploidy analysis of Illumina reads predicts MB as tetraploid, whilst analysis of CpG methylation and retroelements highlights loci in all chromosomes with characteristics consistent with regional centromeres. Orthology analysis identifies several key genes in pathways associated to telomeric and centromeric maintenance, along with methylation and host invasion machinery. A loss of several components of the infection machinery is observed in Microsporidia sp. MB and the wider Enterocytozoonida, consistent with a general trend towards genome size reduction in the clade. ConclusionThis study provides the first complete, telomere to telomere assembly of Microsporidia sp. MB, offering new insight into the genomic architecture of Microsporidia sp. MB and the broader Mrazekiidae family.

genomics↗

bioRxiv2026

Laboratory An. gambiae s.l. mosquito colonies show sustained high transmission of Microsporidia sp. MB and a small fecundity cost

Microsporidia sp. MB, a microsporidian symbiont found naturally in Anopheles mosquitoes, has potential as a novel malaria control tool since it can inhibit Plasmodium development and transmission. The most feasible MB-based Plasmodium control strategy would involve dissemination through live mosquito releases, or release of spores infective to mosquito larvae. To implement either strategy, establishment of stable mosquito colonies carrying MB at a high frequency is likely to be essential. The progeny of field caught An. gambiae s.l from Burkina Faso were isolated for individual egg laying and tested for MB. The progeny of the MB positive females were pooled and this process was repeated for multiple generations. The relative density of MB in different life stages and tissues of the An. coluzzii host was examined using a novel duplex qPCR assay. We also examined the impact of MB on fecundity through individualization for egg laying and counting of eggs. Finally, we examined laid eggs for presence of MB spores. Three An. coluzzii colonies and one An. gambiae s.l hybrid colony were established with high prevalence and density of MB and were maintained for more than two years with minimal intervention. MB prevalence and density was highest in eggs and adult females and lowest in L4 larvae; in adults density was highest in the gonads. Additionally, MB density increased in ovary samples following blood feeding which was likely due to the activation of sporogony. The production of spores is the reason why MB-carrying females lay more white non-hatching eggs and show a small reduction in fecundity. Establishment of several stable MB carrying An. gambiae s.l colonies and understanding the impact of spores on fecundity are significant steps forward in developing MB as a malaria control tool.

microbiology↗

bioRxiv2023

Rapid evolution of Wolbachia genomes in mosquito cell culture

Wolbachia bacterial symbionts are widespread across arthropods where they cause reproductive manipulations and/or confer fitness benefits such as protection against viral pathogens. Their self-spreading ability coupled with their antiviral effect has been harnessed in health programmes to curb the transmission of dengue virus. Comparative genomics of Wolbachia strains has been a useful tool to understand the general trends in the evolution of the symbiont genome; however, short-term evolutionary processes occurring within hosts remain poorly explored. Understanding these short-term dynamics is necessary to provide a more complete picture of Wolbachia evolution and will inform ongoing Wolbachia-based disease control interventions. Here we generated six new mosquito cell lines by introducing a range of Wolbachia strains from Drosophila into the symbiont-free Aedes albopictus Aa23 cell line. Following transinfection, we tracked temporal variation in Wolbachia density and identified de novo mutations through re-sequencing of the symbiont genome. Several mutations were associated with major shifts in bacterial density. Moreover, signs of parallel evolution across cell lines, combined with an excess of non-synonymous mutations, indicate that Wolbachia evolution in cell culture is dominated by selective processes rather than genetic drift. Our results also provide new candidate genes likely to be involved in symbiont density regulation. Altogether, our study demonstrates that cell culture is a valuable tool to investigate symbiont short-term evolution, identify the genetic basis of bacterial density variation and for the generation of new higher-density variants for use in control programmes.

evolutionary biology↗

bioRxiv2023

Transgenic expression of cif genes from Wolbachia strain wAlbB recapitulates cytoplasmic incompatibility in Aedes aegypti.

The endosymbiotic bacteria Wolbachia can invade insect populations by modifying host reproduction through cytoplasmic incompatibility (CI), an effect that results in embryonic lethality when Wolbachia-carrying males mate with Wolbachia-free females. Here we describe a transgenic system for recreating CI in the major arbovirus vector Aedes aegypti using CI factor (cif) genes from wAlbB, a Wolbachia strain currently being deployed to reduce dengue transmission. CI-like sterility was induced when cifA and cifB were co-expressed in testes; this sterility could be rescued by maternal cifA expression, thereby reproducing the pattern of Wolbachia-induced CI. Expression of cifB alone was associated with extensive DNA damage and disrupted spermatogenesis. The strength of rescue by maternal cifA expression was dependent on the comparative levels of cifA/cifB expression in males. These findings are consistent with CifB acting as a toxin and CifA as an antitoxin, with CifA attenuating CifB toxicity in both the male germline and in developing embryos.

microbiology↗

bioRxiv2022

Validation of an engineered Zika virus-like particle vaccine candidate in a mosquito-mouse transmission model

The primary route of Zika virus (ZIKV) transmission is through the bite of an infected Aedes mosquito, when it probes the skin of a vertebrate host during a blood meal. Viral particles are injected into the bite site together with mosquito saliva and a complex mixture of other components. Some of them are shown to play a key role in the augmentation of the arbovirus infection in the host, with increased viremia and/or morbidity. This vector-derived contribution to the infection is not usually considered when vaccine candidates are tested in preclinical animal models. In this study, we performed a preclinical validation of a promising ZIKV vaccine candidate in a mosquito-mouse transmission model using both Asian and African ZIKV lineages. Mice were immunized with engineered ZIKV virus-like particles and subsequently infected through the bite of ZIKV-infected Ae. aegypti mosquitoes. Despite a mild increase in viremia in mosquito-infected mice compared to those infected through traditional needle injection, the vaccine protected the animals from developing the disease and strongly reduced viremia. In addition, during peak viremia, naive mosquitoes were allowed to feed on infected vaccinated and non-vaccinated mice. Our analysis of viral titers in mosquitos showed that the vaccine was able to inhibit virus transmission from the host to the vector. Author summaryZika is a mosquito-borne viral disease, causing acute debilitating symptoms and complications in infected individuals and irreversible neuronal abnormalities in newborn children. The primary vectors of ZIKV are generally considered to be mosquitoes of the genus Aedes, in particular Aedes aegypti. Despite representing a significant public health burden with a widespread transmission in many regions of the world, Zika remains a neglected disease with no effective antiviral therapies or approved vaccines to control and prevent infections. The efficacy of several promising candidate vaccines is however under investigation, mainly through artificial infections (i.e. needle-mediated injections of the virus) in animal models, while it is known that components of the mosquito bite lead to an enhancement of viral infection and spread. In this study, we have also included mosquitoes as viral vectors, demonstrating that the ability of a promising candidate vaccine to protect animals against ZIKV infections after the bite of an infected mosquito, and to also prevent its further transmission. These findings represent an additional crucial step for the development of an effective prevention tool for clinical use. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/503125v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@136fd6borg.highwire.dtl.DTLVardef@137950borg.highwire.dtl.DTLVardef@1a0e01org.highwire.dtl.DTLVardef@8d90d7_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2022

Genome sequencing and comparative analysis of Wolbachia strain wAlbA reveals Wolbachia-associated plasmids are common

Wolbachia are widespread maternally-transmitted bacteria of arthropods that often spread by manipulating their hosts reproduction through cytoplasmic incompatibility (CI). Their invasive potential is currently being harnessed in field trials aiming to control mosquito-borne diseases. Wolbachia genomes commonly harbour prophage regions encoding the cif genes which confer their ability to induce CI. Recently, a plasmid-like element was discovered in wPip, a Wolbachia strain infecting Culex mosquitoes; however, it is unclear how common such extra-chromosomal elements are in Wolbachia. Here we sequenced the complete genome of wAlbA, a strain of the symbiont found in Aedes albopictus. We show that wAlbA is associated with two new plasmids and identified additional Wolbachia plasmids and related chromosomal islands in over 20% of publicly available Wolbachia genome datasets. These plasmids encode a variety of accessory genes, including several phage-like DNA packaging genes as well as genes potentially contributing to host-symbiont interactions. In particular, we recovered divergent homologues of the cif genes in both Wolbachia- and Rickettsia-associated plasmids. Our results indicate that plasmids are common in Wolbachia and raise fundamental questions around their role in symbiosis. In addition, our comparative analysis provides useful information for the future development of genetic tools to manipulate and study Wolbachia symbionts.

genomics↗

bioRxiv2022

Genomic and phenotypic comparisons reveal distinct variants of Wolbachia strain wAlbB

The intracellular bacterium Wolbachia inhibits virus replication and is being harnessed around the world to fight mosquito-borne diseases through releases of mosquitoes carrying the symbiont. Wolbachia strains vary in their ability to invade mosquito populations and suppress viruses in part due to differences in their density within the insect and associated fitness costs. Using whole-genome sequencing, we demonstrate the existence of two variants in wAlbB, a Wolbachia strain being released in natural populations of Aedes aegypti mosquitoes. The two variants display striking differences in genome architecture and gene content. Differences in the presence/absence of 49 genes between variants include genes located in prophage regions and others potentially involved in controlling the symbionts density. Importantly, we show that these genetic differences correlate with variation in wAlbB density and its tolerance to heat stress, suggesting that different wAlbB variants may be better suited for field deployment depending on local environmental conditions. Finally, we found that the wAlbB genome remained stable following its introduction in a Malaysian mosquito population. Our results highlight the need for further genomic and phenotypic characterization of Wolbachia strains in order to inform ongoing Wolbachia-based programmes and improve the selection of optimal strains in future field interventions. ImportanceDengue is a viral disease transmitted by Aedes mosquitoes that threatens around half of the world population. Recent advances in dengue control involve the introduction of Wolbachia bacterial symbionts with antiviral properties into mosquito populations which can lead to dramatic decreases in the incidence of the disease. In light of these promising results, there is a crucial need to better understand the factors affecting the success of such strategies, in particular the choice of Wolbachia strain for field releases and the potential for evolutionary changes. Here we characterized two variants of a Wolbachia strain used for dengue control that differ at the genomic level and in their ability to replicate within the mosquito. We also found no evidence for the evolution of the symbiont within the two years following its deployment in Malaysia. Our results have implications for current and future Wolbachia-based health interventions.

genomics↗

bioRxiv2021

Wolbachia strain wAu differs in cellular perturbation and virus inhibition profiles from previously characterised Wolbachia strains

Some strains of the inherited bacterium Wolbachia have been shown to be effective at reducing the transmission of dengue and other positive-sense RNA viruses by Aedes aegypti in both laboratory and field settings and are being deployed for dengue control. The degree of virus inhibition varies between Wolbachia strains; density and tissue tropism can contribute to these differences but there are also indications that this is not the only factor involved: for example, strains wAu and wAlbA are maintained at similar densities but only wAu produces strong dengue inhibition. We previously reported perturbations in lipid transport dynamics, including sequestration of cholesterol in lipid droplets, with strains wMel / wMelPop in Ae. aegypti. Here we show that strain wAu does not produce the same cholesterol sequestration phenotype despite displaying strong virus inhibition and moreover, in contrast to wMel, wAu antiviral activity was not rescued by cyclodextrin treatment. To further investigate the cellular basis underlying these differences, proteomic analysis of midguts was carried out on Ae. aegypti lines and revealed that wAu-carrying midguts showed a distinct proteome when compared to Wolbachia-free, wMel- or wAlbA-carrying midguts, in particular with respect to lipid transport and metabolism. The data suggest a possible role for perturbed RNA processing pathways in wAu virus inhibition. Together these results indicate that wAu shows unique features in its inhibition of arboviruses compared to previously characterized Wolbachia strains. Author SummaryWolbachia endosymbionts can block transmission of dengue virus by Aedes aegypti mosquitoes, and Wolbachia release programs for dengue control are now being undertaken in several countries. Understanding the mechanisms of Wolbachia-mediated antiviral activity is important for maximizing the efficacy of this control approach. Using functional and proteomic analyses, this study indicates that different strains of Wolbachia perturb cellular functions in diverse ways and display different antiviral profiles. These differences raise the possibility that Wolbachia strain switching could be used to counteract viral escape mutations, should they arise and threaten the efficacy of dengue control programmes.

microbiology↗

bioRxiv2020

High temperature cycles result in maternal transmission and dengue infection differences between Wolbachia strains in Aedes aegypti

Environmental factors play a crucial role in the population dynamics of arthropod endosymbionts, and therefore in the deployment of Wolbachia symbionts for the control of dengue arboviruses. The potential of Wolbachia to invade, persist and block virus transmission depends in part on its intracellular density. Several recent studies have highlighted the importance of larval rearing temperature in modulating Wolbachia densities in adults, suggesting that elevated temperatures can severely impact some strains, while having little effect on others. The effect of a replicated tropical heat cycle on Wolbachia density and levels of virus blocking was assessed using Aedes aegypti lines carrying strains wMel and wAlbB, two Wolbachia strains currently used for dengue control. Impacts on intracellular density, maternal transmission fidelity and dengue inhibition capacity were observed for wMel. In contrast wAlbB-carrying Ae. aegypti maintained a relatively constant intracellular density at high temperatures and conserved its capacity to inhibit dengue. Following larval heat treatment, wMel showed a degree of density recovery in aging adults, although this was compromised by elevated air temperatures. When choosing the Wolbachia strain to be used in a dengue control programme it is important to consider the effects of environmental temperatures on invasiveness and virus inhibition. Author summaryIn the past decades, dengue incidence has dramatically increased all over the world. An emerging dengue control strategy utilizes Ae. aegypti mosquitoes artificially transinfected with the bacterial symbiont Wolbachia, with the ultimate aim of replacing wild mosquito populations. Wolbachia is transmitted from mother to offspring and is able to interfere with virus transmission within the mosquito vector. However, the rearing temperature of mosquito larvae is known to impact on some Wolbachia strains. In this study, we compared the effects of a temperature cycle mimicking natural breeding sites in tropical climates on two Wolbachia strains, currently used for open field trials. We observed that the strain wMel was susceptible to high larval rearing temperatures, while the strain wAlbB resulted to be more stable. These results underlines the importance of understanding the impact of environmental factors on released mosquitoes, in order to ensure the most efficient strategy for dengue control.

microbiology↗

bioRxiv2019

Wolbachia strain wAu efficiently blocks arbovirus transmission in Aedes albopictus

The global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections. Author summaryAedes albopictus, the invasive Asian tiger mosquito, is responsible for numerous outbreaks of important viruses such as dengue and Zika in various regions of the world. The need for alterative control interventions propelled the development of a novel approach that exploits a natural insect symbiont, Wolbachia; when transferred into non-native hosts, these maternally-inherited bacteria are able to interfere with the transmission of mosquito-borne viruses, and also provide reproductive advantages to the host, offering a promising tool for self-sustaining field applications. Currently, several field trials are ongoing for the primary vector of dengue and several other arboviruses, Aedes aegypti, providing encouraging results. In this study, Ae. albopictus has been targeted for a similar approach: this mosquito species naturally carries two strains of Wolbachia. The artificial introduction of a third, non-native strain made this line less able to transmit dengue and Zika viruses and had an impact on its fitness.

microbiology↗

bioRxiv2019

A Microsporidian blocks Plasmodium falciparum transmission in Anopheles arabiensis mosquitoes

Malaria imposes an enormous burden on sub-Saharan Africa, and evidence that incidence could be starting to increase again1 suggests the limits of currently applied control strategies have now been reached. A possible novel control approach involves the dissemination in mosquitoes of inherited symbiotic microbes to block transmission. This strategy is exemplified by the use of transmission-blocking Wolbachia in Aedes aegypti against dengue virus2-7. However, in the Anopheles gambiae complex, the primary African vectors of malaria, there limited reports of inherited symbionts with transmission-blocking capacity8-10. Here we show that a newly discovered vertically transmitted species of Microsporidia symbiont in the An. gambiae complex blocks Plasmodium transmission. Microsporidia MB is present at moderate prevalence in geographically dispersed populations of An. arabienesis in Kenya, localized to the mosquito midgut and ovaries, and is not associated with significant reductions in adult host fecundity or survival. Field collected Microsporidia MB-infected An. arabiensis were never found to harbor P. falciparum gametocytes and on experimental infection with P. falciparum no sporozoites could be detected in Microsporidia MB-infected mosquitos. As a Plasmodium transmission-blocking microbe that is non-virulent and vertically transmitted, Microsporidia MB could be exploited as a novel malaria control tool.

microbiology↗

bioRxiv2019

Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control

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.

microbiology↗

bioRxiv2019

TRIM69 inhibits Vesicular Stomatitis Indiana Virus (VSIV)

Vesicular Stomatitis Indiana Virus (VSIV) is a model virus that is exceptionally sensitive to the inhibitory action of interferons. Interferons induce an antiviral state by stimulating the expression of hundreds of interferon stimulated genes (ISGs). These ISGs constrain viral replication, limit tissue tropism, reduce pathogenicity and inhibit viral transmission. Because VSIV is used as a backbone for multiple oncolytic and vaccine strategies, understanding how ISGs restrict VSIV, not only helps in understanding VSIV-pathogenesis, but helps evaluate and understand the safety and efficacy of VSIV-based therapies. Thus there is a need to identify and characterize the ISGs that possess anti-VSIV activity. Using arrayed ISG expression screening, we identified TRIM69 as an ISG that potently inhibits VSIV. This inhibition was highly specific as multiple viruses (including influenza A virus, HIV-1, Rift Valley Fever Virus and dengue virus) were not affected by TRIM69. Indeed, just one amino acid substitution in VSIV can govern sensitivity/resistance to TRIM69. TRIM69 is highly divergent in human populations and exhibits signatures of positive selection that are consistent with this gene playing a key role in antiviral immunity. We propose that TRIM69 is an IFN-induced inhibitor of VSIV and speculate that TRIM69 could be important in limiting VSIV pathogenesis and might influence the specificity and/or efficacy of vesiculovirus-based therapies.\n\nIMPORTANCEVesicular Stomatitis Indiana Virus (VSIV) is a veterinary pathogen that is also used as a backbone for many oncolytic and vaccine strategies. In natural and therapeutic settings, VSIV infection is sensed by the host and host-cells make proteins that protect them from viruses. In the case of VSIV, these antiviral proteins constrain viral replication and protect most healthy tissues from virus infection. In order to understand how VSIV causes disease and how healthy tissues are protected from VSIV-based therapies, it is crucial that we identify the proteins that inhibit VSIV. Here we show that TRIM69 is an antiviral defence that can potently and specifically block VSIV infection.

microbiology↗