Characterization of Aedes aegypti collagen IV and SPARC expression and the role in midgut repair following blood feeding

Abstract

Aedes aegypti is the major vector of important arboviruses such as dengue, Zika and chikungunya virus. Mosquito blood feeding permits entry of virus into the midgut and causes expansion of the midgut that leads to midgut basement membrane collagen IV damage (Brackney et al., 2021). The nature of collagen IV repair or replacement is largely unstudied and may influence the timing of virus escape from the midgut. While less studied in mosquitoes, in Drosophila development, epithelial cells, the fat body, and hemocytes secrete collagen IV (Ramos-Lewis and Page-McCaw, 2019). These tissues may play a role in mosquito midgut basement membrane repair or replacement. We aim to characterize collagen IV and SPARC expression during mosquito development as well as following blood feeding. We postulate that, hemocytes, the fat body and the midgut express collagen IV and SPARC following blood feeding as well as during development. We extracted RNA from mosquito larvae, male and female pupae, and male and female adults. We also extracted RNA from the midgut, hemolymph, and carcass of adult female unfed and fed mosquitoes at 0, 2, 8, 12, 24, 36, 48,72, and 96 hours post-feeding. We measured the expression of two forms of collagen IV (Cg25C and Viking), and SPARC using RT-qPCR and compared these to RPS17 expression levels. Collagen IV and SPARC expression in the midgut and the carcass after blood feeding may indicate that the midgut and fat body are important for midgut basement membrane repair.