Experimental Coxsackie virus B-3 and B-4 myocarditis in mice.

Mice were inoculated with recently isolated Coxsackie virus B-3 and B-4 intraperitoneally. Severest lesions in the hearts were observed in mice between the age of 7 and 14 days. Grossly yellow-white patches were seen on the hearts of mice from the 7th day to the 6th month after virus inoculation. Microscopically, the heart showed extensive myocardial necrosis, inflammation with small mononuclear cells and calcification on the day of 7. There were myocardial fibrosis and calcification at the 6th month after inoculation with Coxsackie virus B-3, and at the 3rd month after inoculation with Coxsackie virus B-4, but generally pathologic changes were less severe in the latter. Myocardial fibrosis in the present experiment was most prominent among the experiments we have studied. It was confirmed that chronic myocardial fibrosis follows acute Coxsackie virus myocarditis in mice. Possible role of Coxsackie virus myocarditis in the development of cardiomyopathy was briefly discussed.