Cultivation in mosquito cells of sigma virus, the aetiologic agent of hereditary CO 2 sensitivity in Drosophila melanogaster

Abstract

Summary Sigma virus was adapted to growth in the C6/36 clone of Aedes albopictus cells after 3 serial passages in intact Toxorhynchites amboinensis mosquitoes. The virus replicated when the cells were held at 20 and 25°C, but not when they were held at 36°C. Virus was liberated into the supernatant fluid of cultures — which sometimes contained as much as 10 8.0 infectious units per ml. After a high-titred antiserum had been prepared using purified virus grown in cell cultures, it was possible to isolate sigma virus directly in the cell cultures from triturates of infected Drosophila melanogaster flies by using an indirect fluorescent antibody technique as an indicator system. Cell cultures could also be employed for titration of the virus using the same indicator system. This method of viral assay was as sensitive as the inoculation of intact D. melanogaster — at least for cell-culture-adapted virus.