| Résumé: | <p>Aedes aegypti is the primary vector of dengue, which causes an estimated 100 million infections annually. Biocontrol methods, specifically using the endosymbiotic bacterium Wolbachia for population replacement of Wolbachia-infected mosquitoes and population suppression, have recently emerged as novel strategies for dengue vector control. However, the evolutionary adaptation of DENV under Wolbachia pressure within Ae. aegypti could potentially compromise the antiviral properties of this bacterium, thereby affecting the long-term efficacy of this approach in dengue prevention. In addition, the influence of Wolbachia on the vertical transmission of DENV in wild-type Aedes aegypti mosquitoes remains unexplored.</p>
<p>In Chapter 3, I developed a robust whole-genome sequencing assay designed to recover DENV genomes. This assay laid the foundation for the evolutionary exploration detailed in Chapter 4, where I detected and investigated the adaptive variant E203K of DENV-wMel within Ae. aegypti. I have shown the fitness trade-off of this variant in the absence of wMel infection in Ae. aegypti and in human cells. In Chapter 5, I demonstrated that vertical DENV transmission in field-reared Ae. aegypti does occur but is rare, and this vertical transmission rate is reduced significantly in the presence of wMel.</p>
<p>Overall, this thesis contributes to understanding the molecular evolution of DENV in Wolbachia-infected Ae.aegypti, and the significant inhibitory effect of Wolbachia on vertical transmission of DENV. These results have addressed some vital questions in the field of dengue biocontrol and provides insights regarding the long-term benefits of Wolbachia- introgression field releases.</p>
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