Further observations on the mechanism of vertical transmission of flaviviruses by Aedes mosquitoes.

As previously observed for dengue viruses, vertical (i.e., transgenerational) transmission of Japanese and St. Louis encephalitis viruses by Aedes albopictus takes place when the fully formed egg, enclosed in the chorion, is oviposited. The demonstration of such a mechanism for three flaviviruses suggests that vertical transmission of all mosquito-borne flaviviruses may occur in the same manner.