Properties of rabies virus (MNIIVP-74 strain) adapted to Japanese quail embryo cell culture.

The Pasteur strain of fixed rabies virus was adapted to primary cell cultures of Japanese quail embryos and designated as MNIIVP-74. In the course of adaptation the virus pathogenicity for rabbits by the intracerebral route decreased considerably and the pathogenicity for rabbits and adult white mice by extraneural routes was completely lost. After inoculation of Japanese quail embryo cell cultures, a titer of the virus in the culture fluid at 4 days was 6.25--7.0 lg LD50/ml (by the intracerebral inoculation of adult white mice). Viral antigen could be detected by immunofluorescence in the cytoplasm of approximately 60 per cent of the cells. Virus multiplication was accompanied by intensive interferon production. In cultures of BHK-21/13S cells the titer of the virus reached was 5.75 lg LD50/ml at 24 hours and about 30 per cent of the cells were affected. The MNIIVP-74 virus showed a high immunogenic activity in rabbits, guinea pigs and mice.