A SENSITIVE SERODIAGNOSIS OF HEPATITIS-C VIRUS (HCV) INFECTION WITH 2NON-FUSED PEPTIDES - COMPARISON OF ANTIBODY-RESPONSES DETECTED WITH ANEWLY DEVELOPED ASSAY AND A COMMERCIAL 2ND-GENERATION TEST

An enzyme-linked immunosorbent assay (ELISA) was developed for the det ection of anti-HCV antibody. We assayed for antibodies against either oligopeptide (S29-1) deduced from the nucleocapsid gene or the product of nonstructural region (NS3) synthesized in a recombinant Escherichi a coli (S4). To reduce false-positive results induced by non-specific binding of antibodies with a carrier protein and to increase the sensi tivity of an immunoassay, non-fused S4 peptide was prepared by the rec ombinant DNA technique and site-specific proteolysis (by factor Xa). I n 71 non-A, non-B hepatitis patients with chronic liver disease, 70 (9 8.5%) were positive by S29-1/S4 ELISA as well as by a second-generatio n test (Abbott II). On the other hand, of 40 serum samples from blood donors, in which anti-N14 (core) and C100-3 antibodies were not detect ed but hepatitis C virus (HCV) RNA was detectable by polymerase chain reaction (PCR), 24 (60%) were positive by S29-1/S4 ELISA, whereas only 18 (45%) were diagnosed by Abbott II. In addition, based on results i n a small group of 92 blood donors, detection of anti-S29-1/S4 antibod y correlated well with HCV viremia as confirmed by PCR. These results indicated that the preparation of non-fused protein (S4) by recombinan t DNA technique and a combination of S29-1 and S4 as immobilized antig ens in an ELISA provide a sensitive and specific diagnosis for HCV inf ection with good correlation with the presence of viral RNA as confirm ed by PCR.