Engineered antibody-mediated broad-spectrum suppression of human arboviruses in the Aedes aegypti vector.

Mosquito-borne orthoflaviviruses such as dengue and Zika viruses, and alphaviruses such as chikungunya viruses continue to pose global health threats, necessitating innovative vector control strategies. Small antibodies (sAb) such as single-chain variable fragments (scFv) and single-domain antibodies (sdAb) against dengue and chikungunya viral proteins have been applied to neutralize viral infections in mouse and human primary cells. Here, we explored the use of these protective sAbs for the development of transgenic mosquito-based arboviral disease control strategies. We expressed scFv against orthoflaviviruses and sdAb against alphaviruses using a dual bloodmeal-inducible midgut-specific promoter, AeG12, achieving strong expression of both orthoflavivirus scFv and alphavirus sdAb in Aedes aegypti midguts. The presence of sAbs significantly reduced mosquito midgut infections with multiple orthoflaviviruses and alphaviruses, such as dengue, Zika, chikungunya and Mayaro viruses, thus compromising viral transmission by the transgenic mosquitoes. We further augmented virus-blocking by co-expression of sAbs and the siRNA pathway factor Dcr2, proving the utility of combinatorial virus targeting by mechanistically independent antiviral effectors. Our results demonstrate the potential of expressing broadly neutralizing sAbs in mosquitoes, particularly in combination with enhancing endogenous antiviral pathways, as a promising strategy to reduce arbovirus transmission by mosquitoes.