EXPERIMENTAL COXSACKIE-B-3 VIRUS MYOCARDITIS IN GOLDEN-HAMSTERS - LIGHT AND ELECTRON-MICROSCOPY FINDINGS IN A LONG-TERM FOLLOW-UP-STUDY

Following i.p. inoculation with coxsackievirus B3, all 60 weanling Syrian golden hamsters developed severe myocarditis. In the acute phase, light microscopy and EM revealed massive cellular infiltration and myocytolysis in the myocardium which were most prominent on the 5th day and least obvious in 3 wk. In the necrotic myocytes, mitochondria contained moderately electron dense inclusions different from the calcified granules seen in the myocardium of mice with coxsackievirus B3 myocarditis. Macrophages ingested and digested necrotic cell debris, leaving moderate fibrosis but no calcification in the myocardium. Viruses were isolated from the myocardium on day 3-9 and virus particles were seen in a necrotic cardiocyte on day 9. In the chronic phase, most animals developed no cardiomegaly; light microscopy revealed minimal myocardial fibrosis; EM showed various degenerative changes in some cardiocytes. Two animals developed significant cardiomegaly with moderate to marked myocardial fibrosis in the 6th and 14th mo. In 1 heart there was marked biventricular dilatation. In these animals with cardiomegaly, ultrastructural changes of the myocardial cells were similar to those described in congestive cardiomyopathy in man. Golden hamsters appear to be a unique model for a study of the possible relationship between viral myocarditis and idiopathic cardiomyopathy in man.