Development of a enterovirus diagnostic assay system for diagnosis of viral myocarditis in humans.

The coxsackieviruses type B3 (CVB3) are members of the genus Enterovirus of the family Picornaviridae. They are the commonest cause of chronic myocarditis and dilated cardiomyopathy. However, there is still no effective method for diagnosing CVB3 infection in humans. Here, a fast and accurate system that uses a capsid-protein-specific peptide sequence to detect CVB3 in the sera of patients with viral myocarditis was established. The peptide sequence was selected from the whole CVB3 capsid protein sequence by computationally predicting fragments with high antigenicity and low hydrophobicity. Two of eight possible peptide sequences were selected and commercially synthesized. The synthesized peptides encoded either the VP2 or VP1 capsid protein and induced immunoglobulin G antibody expression in immunized rabbits. Anti-VP2 and anti-VP1 sera detected the viral proteins extracted from CVB3-infected HeLa cells. The newly synthesized peptides successfully induced antibody production. These peptides, applied in an ELISA system, detected anti-CVB3 antibodies in virus-infected mouse serum. Moreover, an ELISA system based on the VP2 peptide detected CVB3 infection in patients with positively identified CVB3-induced fulminant myocarditis. These results indicate that these new peptides specifically interact with anti-CVB3 IgG antibodies in mouse and human sera. This ELISA system should be useful for the clinical diagnosis of enterovirus-induced myocarditis.