Identification of an immunodominant epitope within the capsid protein of hepatitis C virus

We have isolated cDNA clones from the 5' end of the Hutchinson strain of hepatitis C virus. Sequences encoding various segments of the HCV structural region were fused to the gene for glutathione S-transferase and analyzed for the expression of hepatitis C virus-capsid fusion proteins. With a set of these fusion proteins, both human and chimpanzee immune responses to capsid were studied. An immunodominant epitope was located within the amino-terminal portion of capsid that is preferentially recognized by antibodies in both human and chimpanzee hepatitis C virus-positive sera. In addition, analyses of sequential serum samples taken from humans and chimpanzees with either chronic or apparently self-limited infections revealed that a strong anti-capsid response develops rapidly after onset of infection.