Immune responses of blood donors to peptides of various lengths and those with genotypic sequence variations corresponding to the N-terminal portion of the core protein of hepatitis C virus.

Immune reactivities of blood donor sera with the peptides of various lengths (24, 30, 40 and 50 mer) and those with genotypic sequence variations in the N-terminal portion of the core protein of hepatitis C virus (HCV) were compared by enzyme-linked immunosorbent assays. It was found that a 40-mer oligopeptide (amino acids 2-41) was recognized more frequently than other peptides even in serum samples that did not react with the C22-3 (core) by the recombinant immunoblot assay (RIBA-II). On the other hand, a 30-mer peptide (amino acids 1-30) had good correlation with viremia as confirmed by the polymerase chain reaction (PCR). In addition, four individuals showed the obvious differences in the immune responses to 30-mer oligopeptides representing the 4 genotypic variations. As a result, some samples that were PCR-positive but nonreactive by a commercial assay were found to react with short synthetic peptides in the N-terminal portion of the core protein.