Pathogenicity of Murine Hepatitis Virus Recovered from Infant Swiss Mice. ∗

Abstract

Summary

A murine hepatitis virus designated MHV (SR4) was recovered from infant Swiss mice of an outside source during a natural outbreak of disease. Intraperitoneal injection of 1- and 2-day-old nurslings from the Swiss colony of the Rockefeller Institute resulted in focal or semi-diffuse necrosis of the liver and mortality rates of 45 and 39%. The virus was less active in 5-day-old nurslings and essentially inactive alone in weanlings. It was established in the latter, however, on combination with ascites tumor cells.

MHV (SR4) was also transmitted to 1- and 2-day-old nurslings by feeding and was demonstrable in their intestinal washings. It was not communicable from either injected or fed nurslings to untreated litter mates exposed to them. One-, 2-, and 5-day-old nurslings injected intracerebrally with the virus showed incoordination and mortality rates of 73-75% but weanlings were unaffected. Necrotic lesions were demonstrable in the brains and livers of the nurslings.