Response of nude mice to a mouse hepatitis virus isolated from a wasting nude mouse.

Chronic active hepatitis was produced in nude mice after inoculation with a mouse hepatitis virus from a natural nude case which was incapable of causing fatal infection in haired heterozygous mice without cortisone. Survival time of infected nude mice varied greatly from 1 to 10 weeks after the inoculation. Degeneration and necrosis of hepatocytes, apparition of small and megalocytic hepatocytes, and infiltration of lymphocytes and plasma cells with fibrosis, were most remarkable in those which died 3 weeks or more after inoculation. No such severe hepatic lesions were recognized in heterozygous haired litter-mates after inoculation of the same virus. Necrotic lesions with poor inflammatory reactions were seen in the brain of all infected and dead nude mice, while some cerebral lesions with apparent perivascular infiltration were detected in heterozygous ones only at early stage of infection.