The location of San Angelo virus in developing ovaries of transovarially infected Aedes albopictus mosquitoes as revealed by fluorescent antibody technique.

Aedes albopictus adult female mosquitoes, transovarially infected with San Angelo (SA) virus, were examined by fluorescent antibody technique during various stages of ovarian development to determine how the virus enters the egg. Upon emergence from the day of adulthood, it was visible in the follicular epithelium, oocytes and nurse cells of the primary follicles. In the 72-hour period between the ingestion of blood and oviposition, there was a marked increase in the amount of viral antigen in the oocyte, indicating rapid virus accumulation. After oviposition, SA viral antigen was also seen in the secondary ovarian follicles. The observed sequence of infection of the mosquito ovariole with SA virus is analogous to that described with certain endosymbionts of insects.