Identification of a putative shared epitope between Coxsackie virus B4 and alpha cardiac myosin heavy chain

Molecular mimicry is an important postulated mechanism for autoimmunity in viral myocarditis. The 356-1 monoclonal antibody neutralizes Coxsackie virus B4 by binding to the VP1 protein and cross-reacts with mouse alpha cardiac myosin heavy chain. We used this monoclonal antibody to screen a lambda gt11 expression library made from CD-1 mouse hearts. Of the 48 positive plaques/10(6) recombinant phages examined, 14 of the strongest-reacting clones were purified for additional studies. The inserts were amplified by polymerase chain reaction and the amplified products ranged from about 150 to 1400 bp in size. Northern hybridization using these inserts demonstrated that 11 out of 14 reacted with a message equivalent to that of cardiac myosin in size. Additional Southern hybridization studies suggested that these 11 inserts contained overlapping sequences in the light meromyosin fragment of cardiac myosin. Sequence analysis confirmed that these 11 independent, recombinant clones contained a common sequence representing amino acid residues 1299-1647. Within this fragment only one isoform-specific site matched the observed reactivity pattern of 356-1 among hearts from various species. Thus, we were able to identify a putative shared epitope represented by residues 1632-1647.