[Detection of viral genomes in myocarditis]

Although much evidence favors the concept that dilated cardiomyopathy could be a postviral disease, the actual prevalence and pathogenesis of viral heart disease in dilated cardiomyopathy has not been well explored, since the diagnosis of viral infection is still difficult. The recently developed polymerase chain reaction (PCR) has made it possible to amplify a few copies of viral genome and has shown that viral genomes persist long after viral infection. The PCR is a promising method for testing possible viral etiology. We have found that antiheart antibodies associated with a murine model of myocarditis increased the intracellular free Ca2+ concentration through the activation of Ca(2+)-permeable cation channels in isolated ventricular cells. Marked induction of Mn-SOD and Cu/Zn-SOD mRNA was found in the heart with viral myocarditis and oxygen radicals may play an important role in the pathogenesis of viral myocarditis. Our recent studies revealed an increase in the circulating cytokines in patients with acute myocarditis and cardiomyopathy and suggested that cytokines play some role in the pathogenesis of myocardial injury in these diseases. In our animal model of EMC virus myocarditis, plasma tumor necrosis factor (TNF)-alpha was elevated in the acute stage and exogenously administered anti TNF-alpha antibody improved the survival and myocardial lesion, suggesting the importance of TNF-alpha in the pathogenesis.