Comparative analysis of the cellular dynamics in the midgut epithelium from field and laboratory samples of Aedes aegypti

Aedes aegypti mosquitoes are primary vectors of significant viral diseases like dengue, Zika, and chikungunya. Transmission occurs when infected female mosquitoes transfer pathogens via blood meals to uninfected individuals during subsequent feedings. The mosquito gut epithelium represents the initial barrier, making cellular dynamics within it crucial for vector competence. Cellular studies often focus on lab-reared mosquito strains, raising questions about the applicability of findings to field mosquitoes.
To address this, we compared cellular dynamics in midgut epithelia of field and lab mosquitoes. In a dengue-endemic Guatemala location, we sought insights into local mosquito strain characteristics' impact on vector competence. Wild mosquitoes were immediately exposed to EdU-treated sugar water to assess DNA synthesis in midgut tissues. After dissection, groups based on blood-feeding status (non-blood-fed, gravid, semi-gravid) were established. Using a single mosquito leg for genotyping, only Ae. aegypti mosquitoes were considered. Fixation and immunostaining identified intestinal stem cells (ISCs) and cells undergoing mitosis and endocycling/DNA replication in all groups.
Comparing mitotic events and DNA synthesis in wild populations, no significant difference was found when compared to lab-reared strains under the same conditions. These initial findings suggest broadly conserved cellular dynamics rates in Ae. aegypti strains. Potentially, lab-strain findings could extend to field strains from endemic regions like Guatemala. This study enhances vector competence understanding, emphasizing the importance of considering both lab and field dynamics in disease transmission studies.