Myocarditis in mice infected with Coxsackie virus B3

Perimyocarditis in the heart of BALB/c mice infected with Coxsackie virus group B type 3 (CB3) was studied to determine whether it is limited to the right perimyocardium and to show whether or not perimyocarditis or myocardial lesions are produced in both left and right ventricles. CB3 was recovered from the heart on days from 2 to 13 after inoculation, but thereafter no virus was isolated from any part of the heart. Histopathologically, from days 1 to 4, hyaline or granular degeneration and necrosis of the muscle fibres with or without calcium deposits and an inflammatory mononuclear cell infiltration was limited to the right perimyocardium. On days 6 to 18, however, degeneration and necrosis of the muscle fibres and an inflammatory mononuclear cell infiltration were found not only in the right perimyocardium, but also in both left and right ventricular wall, the left perimyocardium, both right and left endomyocardium and the septum. In the right ventricular lesions, the incidence and intensity of the histopathological changes in the perimyocardium were greater than those in the muscular layer or septum. In contrast, in left ventricular lesions, the incidence and intensity of the histopathological changes in the muscular layers were greater than those in the peri- and endo--cardium. It is inferred, therefore, that the right perimyocardium and left ventricular wall are more susceptible to CB3 infection than right ventricular wall or left peri- and endocardium. It is concluded that CB3 can produce not only right-sided perimyocarditis, but also both right and left ventricular lesions and endocardial or septal changes in the mouse heart.