Science Alert April 18, 2023
Mosquito transmission of dengue viruses to humans starts with infection of skin resident cells at the biting site. There is great interest in identifying transmission-enhancing factors in mosquito saliva in order to counteract them. An international team of researchers (Singapore, USA – University of Texas, University Virginia, Spain, France) has discovered high levels of the anti-immune subgenomic flaviviral RNA (sfRNA) in dengue virus 2-infected mosquito saliva. They confirmed that sfRNA was present in saliva. They showed that salivary sfRNA was protected in detergent-sensitive compartments. Based on this hypothesis, they visualized viral RNAs in vesicles in mosquito saliva and noted a marked enrichment of signal from 3’UTR sequences, which was consistent with the presence of sfRNA. They showed that incubation with mosquito saliva containing higher sfRNA levels results in higher virus infectivity in a human hepatoma cell line and human primary dermal fibroblasts. According to the researchers sfRNA present in salivary extracellular vesicles is delivered to cells at the biting site to inhibit innate immunity and enhance dengue virus transmission… read more. Open Access TECHNICAL ARTICLE
sfRNA in salivary vesicles is transported into cells to enhance infection at the biting site. Credit: PLOS Pathogens, March 30, 2023Â