Exploring the importance of mosquito hemocoelic and salivary gland components during host-pathogen interactions

Abstract

Traversal of the hemocoel, avoiding or surviving interactions with the insect’s innate immune system, invasion of the female mosquito’s salivary glands, and injection into the vertebrate host, are necessary steps for disease transmission by mosquitoes. These processes represent perilous stages in the life-cycle of mosquito-vectored pathogens, which could be targeted in disease control strategies. In this dissertation, I explore three distinct aspects of mosquito physiology that come into play during pathogen migration through the hemocoel: (1) the mosquito circulatory system, (2) the cellular immune system and (3) the salivary gland surface. I characterized hemolymph propulsion and flow for the first time in mosquitoes and found that it was rapid, suggesting that pathogens use passive migration to traverse the hemocoel. I investigated the mosquito cellular immune response to pathogens and found that infection induces hemocyte proliferation and the aggregation of hemocytes on the surface of the heart. Lastly, I found that mosquito SGS proteins are involved in blood feeding, and are a prevalent and immunogenic component of the mosquito saliva.