Robert Manuel, a junior from California State Polytechnic University, Pomona, worked with Ruby Harrison in the lab of Dr. Mike Strand to examine the relationship between mosquito gut biota and dengue infection.
Abstract: The mosquito Aedes aegypti is the primary vector of dengue virus (DENV). Prior studies report increased susceptibility of A. aegypti to DENV infection, and higher pathogen burden when adult females are treated with antibiotics. This suggests a role for the microorganisms that colonize the digestive tract of mosquitoes (gut microbiota) in susceptibility to DENV infection. We tested the hypothesis that microbe-depleted A. aegypti are more susceptible to DENV infection by comparing three treatments: axenic mosquitoes with no gut microbiota, gnotobiotic mosquitoes harboring only Escherichia coli, and conventional mosquitoes with a natural community of gut microbes. We validated the status of these mosquitoes using both culturing methods and PCR. We then assessed DENV presence/absence in each treatment fourteen days after feeding adult females an infected blood meal. Consistent with our working hypothesis, a larger proportion of axenic mosquitoes were infected with DENV than conventional mosquitoes. Proportions of axenic and gnotobiotic mosquitoes infected with DENV were nearly identical. However, our treatments had no effect on DENV dissemination among females that were infected. In summary, these results suggest A. aegypti with a more diverse gut microbiota are more resistant to DENV infection than axenic females but E. coli alone provides no increase in resilience.