A naturally isolated symbiotic bacterium suppresses flavivirus transmission by Aedes mosquitoes

The commensal microbiota of the mosquito gut plays a complex role in determining the vector competence for arboviruses. Here, we identified a bacterium from the gut of field Aedes albopictus mosquitoes, named Rosenbergiella sp. YN46 (Rosenbergiella_YN46), that rendered mosquitoes refractory to infection with dengue and Zika viruses. Inoculation of 1.6×103 colony forming units (CFUs) of Rosenbergiella_YN46 into A. albopictus mosquitoes effectively prevents viral infection. Mechanistically, this bacterium secretes glucose dehydrogenase (RyGDH), which acidifies the gut lumen of fed mosquitoes, causes irreversible conformational changes in the flavivirus envelope protein that prevent viral entry into cells. In semi-field conditions, Rosenbergiella_YN46 exhibits effective transstadial transmission in field mosquitoes, which blocks transmission of dengue virus by newly emerged adult mosquitoes. The prevalence of Rosenbergiella_YN46 is greater in mosquitoes from low-dengue areas (52.9%~91.7%) than in those from dengue-endemic regions (0%~6.7%). Rosenbergiella_YN46 may offer an effective and safe lead for flavivirus biocontrol.