Aedes aegypti gelsolin is required for Zika virus dissemination from the midgut to secondary tissues

Aedes aegypti is a major vector transmitting arboviruses such as yellow fever, dengue I-IV, Zika (ZIKV), and chikungunya viruses. The midgut escape barrier is an important tissue barrier to arbovirus infection in mosquito. Our previous studies have found that midgut distension from a blood meal (or protein meal, saline meal) increases the pore size of the basal lamina (BL) thereby enabling ZIK virions to traverse the BL after bloodmeal digestion. To further investigate the midgut escape mechanism, timsTOF Pro based quantitative proteomics were performed to study the proteomic change in the midgut following saline meal ingestion at early time points (0.5, 12, 24, 36, 48, 72, and 96 h post feeding). In total, up to 460 significantly differentially expressed proteins were identified, which were involved in functions of catalytic activity, binding, structural molecule activity and transporter activity. Eight of those differentially expressed proteins were potentially involved in BL remodeling. We transiently silenced the genes encoding these proteins one-by-one in Ae. aegypti and provided the mosquitoes with blood meals containing ZIKV.   Silencing of gelsolin significantly decreased the viral infection rate in secondary tissues but not in the midgut. A heterozygous knock-out line of gelsolin using CRISPR/Cas9 genome editting was established. These results allow the conclusion that gelsolin is involved in ZIKV midgut escape but not in midgut infection.