Exploring dose-response relationships in Aedes aegypti survival upon bacteria and arbovirus infection

A detailed understanding of host fitness changes upon variation in microbe density is a central aim of infection biology. Here, we applied dose-response curves to study Aedes aegypti survival upon exposure to different microbes. We infected female mosquitoes with Listeria monocytogenes, a model bacterial pathogen, Dengue 4 virus and Zika virus, two medically relevant arboviruses, to understand the distribution of mosquito susceptibility and net fitness (survival) upon microbe exposure. By correlating microbe loads and host health, a method to quantify disease tolerance, we found that a blood meal promotes tolerance in our systemic bacterial infection model and that mosquitoes orally infected with bacteria are more tolerant than insects infected through injection. We also showed that Aedes aegypti has a high disease tolerance profile upon arbovirus infection but, under the conditions tested, was slightly less tolerant to Zika virus when compared to Dengue virus. Disease tolerance is only beginning to be explored in mosquitoes and our results provide a first systematic analysis of how Aedes aegypti survival varies upon different infection strengths of bacteria and arboviruses.