Isolation of mouse hepatitis virus from infant mice with fatal diarrhea.

An epizootic of fatal diarrhea occurred in mice which were approximately 10 days of age. The enteric lesions were similar to those reported in lethal intestinal virus of infant mice, but many diseased mice also had necrotic hepatitis. Mouse hepatitis virus antigen was demonstrated in the affected intestine and liver, and a virus that produced syncitium formation in mouse brain tumor cell culture was isolated from the intestines, livers, and brains. The virus was capable of producing intestinal and hepatic lesions similar to the naturally occurring disease after inoculation into suckling mice. Electron microscopy revealed viral particles within affected intestinal epithelial cells of the inoculated mice.