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 v irus 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 sampl es were obtained from patients with myocarditis or dilated cardiomyopathy ( DCM). Control samples were collected from 11 subjects who had died accident ally or of noncardiovascular disease. Viral antigen was detected by an impr oved immunohistochemical technique using an enterovirus group-specific anti body 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 cytopla sm of myocytes. Intense immunostaining was observed in acute myocarditis, w hereas 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 ch ain reaction, correlating with antigen detection (kappa=0.6+/-0.21). Neithe r viral antigen nor RNA was detected in any controls. Conclusions-Our findings demonstrate a direct link between enterovirus infe ction and some myocarditis or DCM cases. The pattern of VP1 detection may c orrelate with disease stage and severity. The data suggest that viral prote in synthesis may be involved in persistent enterovirus infection in the pat hogenesis of DCM.