CHARACTERIZATION AND MAPPING OF A B-CELL IMMUNOGENIC DOMAIN IN HEPATITIS-C VIRUS E2 GLYCOPROTEIN USING A YEAST PEPTIDE LIBRARY

To identify conserved humoral antigenic determinants within the hepati tis C virus (HCV) envelope protein E2, we expressed a peptide library containing random short fragments of the HCV envelope in yeast. Clones were identified using a monospecific rabbit antibody to a region down stream of the E2 hypervariable region. The clones define the limits of two original antigenic domains: a major one (aa 493-576) and a minor one (aa 535-606). The major antigenic domain maps in a region that dis plays a high degree of homology within a (HCV) subtype (92-97.6% ident ity). Yeast-encoded determinants were characterized by Western blot an alysis, N-glycosidase F digestion, and using a panel of synthetic pept ides. The data suggest that the major antigenic domain contains at lea st two determinants, one of them mimicked by an 18-mer peptide (aa 514 -531). ELISA and competitive inhibition assays demonstrated that: (1) the determinants appear subtype 1a-specific, (2) seroprevalence of ant ibody to the determinants is rather low (20.6%), and (3) donors show a heterologous response to the different determinants. Antibody respons e to the E2 determinants was studied in HCV-infected chimpanzees and p ost-transfusion-associated NANB hepatitis cases. The antibody response was found during chronic infection and may not be effective for virus clearance. (C) 1994 Academic Press, Inc.