Biology subjects

Robinson, K. L.

Publications and source records attributed to Robinson, K. L..

3 recordsLinked to original sources

bioRxiv2022

A wMel Wolbachia variant in Aedes aegypti from field-collected Drosophila melanogaster with increased phenotypic stability under heat stress

Mosquito-borne diseases such as dengue, Zika and chikungunya remain a major cause of morbidity and mortality across tropical regions. Population replacement strategies involving the wMel strain of Wolbachia are being used widely to control mosquito-borne diseases transmitted by Aedes aegypti. However, these strategies may be influenced by environmental temperature because wMel is vulnerable to heat stress. wMel infections in their native host Drosophila melanogaster are genetically diverse, but few transinfections of wMel variants have been generated in Ae. aegypti mosquitoes. Here we successfully transferred a wMel variant (termed wMelM) originating from a field-collected D. melanogaster population from Victoria, Australia into Ae. aegypti. The new wMelM variant (clade I) is genetically distinct from the original wMel transinfection (clade III) generated over ten years ago, and there are no genomic differences between wMelM in its original and transinfected host. We compared wMelM with wMel in its effects on host fitness, temperature tolerance, Wolbachia density, vector competence, cytoplasmic incompatibility and maternal transmission under heat stress in a controlled background. wMelM showed a higher heat tolerance than wMel, with stronger cytoplasmic incompatibility and maternal transmission when eggs were exposed to heat stress, likely due to higher overall densities within the mosquito. Both wMel variants had minimal host fitness costs, complete cytoplasmic incompatibility and maternal transmission, and dengue virus blocking under standard laboratory conditions. Our results highlight phenotypic differences between closely related Wolbachia variants. wMelM shows potential as an alternative strain to wMel in dengue control programs in areas with strong seasonal temperature fluctuations.

microbiology↗

bioRxiv2021

A decade of stability for wMel Wolbachia in natural Aedes aegypti populations

Mosquitoes carrying Wolbachia endosymbionts are being released in many countries for arbovirus control. The wMel strain of Wolbachia blocks Aedes-borne virus transmission and can spread throughout mosquito populations by inducing cytoplasmic incompatibility. Aedes aegypti mosquitoes carrying wMel were first released into the field in Cairns, Australia, over a decade ago, and with wider releases have resulted in the near elimination of local dengue transmission. The long-term stability of Wolbachia effects is critical for ongoing disease suppression, requiring tracking of phenotypic and genomic changes in Wolbachia infections following releases. We used a combination of field surveys, phenotypic assessments, and Wolbachia genome sequencing to show that wMel has remained stable in its effects for up to a decade in Australian Ae. aegypti populations. Phenotypic comparisons of wMel-infected and uninfected mosquitoes from near-field and long-term laboratory populations suggest limited changes in the effects of wMel on mosquito fitness. Treating mosquitoes with antibiotics used to cure the wMel infection had limited effects on fitness in the next generation, supporting the use of tetracycline for generating uninfected mosquitoes without off-target effects. wMel has a temporally stable within-host density and continues to induce complete cytoplasmic incompatibility. A comparison of wMel genomes from pre-release (2010) and nine years post-release (2020) populations show few genomic differences and little divergence between release locations, consistent with the lack of phenotypic changes. These results indicate that releases of Wolbachia-infected mosquitoes for population replacement are likely to be effective for many years, but ongoing monitoring remains important to track potential evolutionary changes. Author summaryWolbachia are endosymbionts that can block the transmission of arboviruses by mosquitoes. Aedes aegypti mosquitoes carrying the wMel strain of Wolbachia have been released in population replacement interventions, which aim to establish wMel in mosquito populations, thereby reducing their ability to spread disease. Wolbachia population replacement programs began only a decade ago, raising uncertainty about their long-term effectiveness. Here we provide a comprehensive assessment of the long-term stability of wMel from the very first Wolbachia population replacement release. We show that there is no evidence for changes in the phenotypic effects of wMel in mosquitoes, and confirm that the wMel genome has changed very little in the decade since field releases began. wMel remains at high levels within mosquitoes, suggesting that its ability to block virus transmission has been retained. Our data provides confidence that Wolbachia population replacement releases will provide ongoing protection against arbovirus transmission.

evolutionary biology↗

bioRxiv2021

A wAlbB Wolbachia transinfection displays stable phenotypic effects across divergent Aedes aegypti mosquito backgrounds

Aedes mosquitoes harboring intracellular Wolbachia bacteria are being released in arbovirus and mosquito control programs. With releases taking place around the world, understanding the contribution of host variation to Wolbachia phenotype is crucial. We generated a Wolbachia transinfection (wAlbBQ) in Aedes aegypti and performed backcrossing to introduce the infection into Australian or Malaysian nuclear backgrounds. Whole Wolbachia genome sequencing shows that the wAlbBQ transinfection is near-identical to the reference wAlbB genome, suggesting few changes since the infection was first introduced to Ae. aegypti over 15 years ago. However, these sequences were distinct from other available wAlbB genome sequences, highlighting the potential diversity of wAlbB in natural Ae. albopictus populations. Phenotypic comparisons demonstrate effects of wAlbB infection on egg hatch and nuclear background on fecundity and body size, but no interactions between wAlbB infection and nuclear background for any trait. The wAlbB infection was stable at high temperatures and showed perfect maternal transmission and cytoplasmic incompatibility regardless of host background. Our results demonstrate the stability of wAlbB across host backgrounds and point to its long-term effectiveness for controlling arbovirus transmission and mosquito populations.

evolutionary biology↗