Detection of enteroviral genome in the myocardium from patients with viral myocarditis and dilated cardiomyopathy, and animals with Coxsackievirus myocarditis

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To study the viral etiology of dilated cardiomyopathy (DCM), we examined for the presence of enteroviral RNA in myocardial biopsics from patients with DCM,myocarditis (MC), or other cardiac discases, and myocardial fissues of animal models of coxasckievirus (CV) B3 myocarditis, using polymerase chain reaction (PCR) and in situ hybridization (ISH).Myocardial biopsies from 154 patients were examined for the presence of enteroviral genome in NC,NS and POL region by RT-PCR.The positive incidence was 20% and there was no significant difference among DCM,MC and other cardiac diseases. We also examined the genotypes of enteroviruses detected in myocardial biopsies by PCR-SSCP analysis. Most of the genotypes were not corresponded with those of CV group B and a particular type of enterovirus was not present in DCM heart. In animal models of CVB3 virus myocarditis, the viral genome was detected up to the 28th day of inoculation in C3H/He mice. Light microscopic ISH with a cDNA probe for CVB showed clusters of positive signals in the areas of myocardial necrosis and cell infiltration. With electron microscopic ISH,CVB3-RNA was detected in the cytoplasm of cardiocytes, between the myofibrils, near the mitochondria, and in tubular or vesicular structures. Viral RNA was also detected in necrotic debri, in the cytoplasm of macrophages and fibroblasts. These findings suggest that CVB3 RNA is replicated in the cytoplasm of cardiocytes, transferred into tubular or vesicular structures, released into the interstitium, and phagocytosed by macrophages. Some positive signals were also detected in the cytoplasm of cardiocytes showing close contact with infiltrating lymphocytes, suggesting that the lymphocytes recognized virus-infected cardiocytes and caused to cell-mediated immune cardiocyte damage.