ANTIBODY TO HEPATITIS-C VIRUS 2ND ENVELOPE (HCV-E2) GLYCOPROTEIN - A NEW MARKER OF HCV INFECTION CLOSELY ASSOCIATED WITH VIREMIA

The second envelope protein (E2) of the hepatitis C virus (HCV) was cl oned and expressed in Chinese hamster ovary (CHO) cells. This E2 glyco protein was purified using ion exchange and lectin chromatography and used to construct an enzyme immunoassay for HCV E2 antibodies. The ass ay was shown to have good specificity, and detection of E2 antibodies was positively correlated (97.3%) to the presence of HCV RNA in serum and plasma. A high concordance between HCV 2.0 and E2 EIA reactivities was also observed. E2 antibody was the first serological marker to ap pear in 3/5 HCV seroconversion panels. This work demonstrated that 42. 4% of core and 15.4% of NS3 indeterminate specimens also contained ant ibodies to E2, suggesting that HCV infection had occurred in these ind ividuals. The E2 antibody assay was used to evaluate HCV 2.0 EIA-posit ive, HCV 3.0 EIA-negative plasma donors with indeterminate reactivity on RIBA HCV 2.0 or MATRIX HCV 1.0. Several HCV 3.0-negative specimens were shown to contain E2 antibodies in addition to an original indeter minate serological marker, primarily core. It is concluded that anti-E 2 is a useful marker for determining HCV infection, and that the prese nce of antibodies to two nonoverlapping viral gene products suggests t rue HCV exposure. New HCV 3.0 blood screening tests should detect HCV 2.0-positive donors who present with an indeterminate pattern by RIBA or MATRIX and who also carry E2 antibodies. (C) 1995 Wiley-Liss, Inc.