Engineered resistance in Aedes aegypti to a West African and a South American strain of yellow fever virus.

Double subgenomic Sindbis (dsSIN) viruses were engineered to transduce mosquito cells with antisense RNA derived either from the premembrane (prM) or polymerase (NS5) coding regions of the 17D vaccine strain of yellow fever virus (YFV). Aedes albopictus C6/36 cells were infected at high multiplicities of infection (MOI) with each dsSIN virus. Forty-eight hours later, the transduced cells were challenged with an MOI of 0.1 of the Asibi strain of YFV. At 72-hr postchallenge, the cells were assayed by immunofluorescence for the presence of YFV antigen. Cells transduced with prM or NS5 antisense RNAs derived from the YFV genome displayed no YFV-specific antigens. In contrast, cells infected with control dsSIN viruses that expressed no antisense RNA or dengue virus-derived antisense RNAs were permissive for the challenge virus. To analyze resistance in the mosquito, five log10 50% tissue culture infective doses (TCID50) of each dsSIN virus and three log10TCID50 of either a West African (BA-55) or South American (1899/81) strain of wild-type YFV were coinoculated into Ae. aegypti. Mosquitoes transduced with effector RNAs targeting the prM or NS5 gene regions did not transmit West African YFV and poorly transmitted the South American strain of YFV.