Enteroviral capsid protein VP1 is present in myocardial tissues from some patients with myocarditis or dilated cardiomyopathy.

BACKGROUND There are still discrepancies in the association of enterovirus and myocardial disease, partially due to lack of data on the detection of virus antigens in tissues. It is desirable to localize enteroviral antigens so as to establish a link between the two and to study mechanisms of virus persistence. METHODS AND RESULTS Nineteen fixed explanted or postmortem myocardial samples were obtained from patients with myocarditis or dilated cardiomyopathy (DCM). Control samples were collected from 11 subjects who had died accidentally or of noncardiovascular disease. Viral antigen was detected by an improved immunohistochemical technique using an enterovirus group-specific antibody to viral capsid protein VP1. Nine of 11 myocarditis cases (81.8%) and 6 of 8 DCM cases (75%) were positive. Signals were localized in the cytoplasm of myocytes. Intense immunostaining was observed in acute myocarditis, whereas VP1 was detected in scattered myocytes in chronic myocarditis or DCM. Enteroviral RNA was detected in 6 of 11 myocarditis samples (54.5%) and 3 of 8 DCM samples (37.5%) by the reverse transcription-nested polymerase chain reaction, correlating with antigen detection (kappa=0.6+/-0.21). Neither viral antigen nor RNA was detected in any controls. CONCLUSIONS Our findings demonstrate a direct link between enterovirus infection and some myocarditis or DCM cases. The pattern of VP1 detection may correlate with disease stage and severity. The data suggest that viral protein synthesis may be involved in persistent enterovirus infection in the pathogenesis of DCM.