IMMUNE RECOGNITION OF LINEAR ANTIGENIC REGIONS WITHIN THE HEPATITIS-BPRE-C AND C-GENE TRANSLATION PRODUCTS USING SYNTHETIC PEPTIDES

The antibody recognition of linear regions within the amino acid (aa) sequence of hepatitis B (HB) core antigen (HBcAg), e antigen (HBeAg), and pre-C region was investigated in 46 patients infected with hepatit is B virus (HBV), and one immunized rabbit. Peptide analogues were syn thesized to cover the complete product of the C-gene, including the pr e-C region using various synthetic methods. Two carriers of hepatitis B surface antigen (HBsAg) with anti-HBe, recognized pin-bound decapept ides covereing amino acid (aa) 76-83 of HBc/eAg, and the most essentia l residues were found to be Asp(78), Pro(79), Arg(82), and Asp(83). Pr e-C peptides were recognized by IgG1 or lgG3 in sera from two out of t en cases with acute HB, in four out of twelve sera from HBeAg-positive carriers of HBsAg, and in two out of twelve sera from anti-HBe-positi ve carriers of HBsAg. Two sera from the cases of acute HB showed stron g reactivity of the lgG3 isotype with HBc/eAg peptides 61-85. Five of the sera from HBeAg-positive carriers of HBsAg were weakly reactive wi th peptides 41-60, 61-85, 121-140, and/or 141-160. Eight of the sera f rom anti-HBe-positive carriers of HBsAg recognized aa 121-140 of HBc/e with IgG1, lgG3, and/or lgG4 isotypes. IgG from one immunized rabbit recognized peptides 1-20, 61-85, and 71-90, and the T-cells recognized peptides 1-20 and 71-90. Thus, human and rabbit antibodies recognize linear antigenic regions within the pre-C, and within regions 1-20, 41 -60, 61-85, 121-140, and 141-160 of HBcAg. Thus, the major HBc site is likely to comprise more than one part of the HBcAg sequence, of which a sequence within residues 61-85 might be a linear component.