Vector Competence of Aedes aegypti for Zika Virus and Effects of Colonization
The following dissertation aims to determine how vector colonization of influences the vector competence of Aedes aegypti for Zika virus (ZIKV) as well as the microbiome as a correlating factor. Ae. aegypti is the vector of multiple arthropod-borne viruses including dengue, yellow fever, and Zika virus, making it one of the most globally significant disease vectors and is studied in laboratories world-wide with significant research focus on vector competence studies. Many of these studies, however, utilize strains of Ae. aegypti that have been colonized in insectaries for laboratory use and may not reflect the phenotype of wild mosquitoes. While studies have shown differences lab adaptation of mosquitoes resulting in an altered phenotype compared to field mosquitoes, a comprehensive study examining the process of adaptation and effects on vector competence has not been conducted. I hypothesize that the colonization of Ae. aegypti results in an increase in vector competence for ZIKV, correlated with a change in microbiome diversity and composition. First, the vector competence of multiple species of mosquitoes (Ae. aegypti, Ae. albopictus, and Culex quinquefasciatus) was determined for ZIKV, using various strains of both virus and each vector species. A field-collected population of Ae. aegypti was then colonized and experimentally examined for vector competence for ZIKV and microbiome over the course of ten generations. I found that the vector competence of this population did increase over the course of the study and that this change occurred abruptly after multiple generations, resulting in two distinct groups of low and high competence. I then identified a number of bacteria that exhibited different levels of abundance between the low and high competence groups, many of which remain uncharacterized in the mosquito microbiome. Further studies to elucidate the role of these bacteria in determining vector competence as well as the development methods to minimize the effects of colonization could lead to better standardization across vector competence studies and increased relevance to field mosquitoes. These findings are incorporated into the existing literature with recommendations on the design of vector competence studies.