QUANTITATIVE-ANALYSIS OF ANTIBODY TO HEPATITIS-C VIRUS ENVELOPE-2 GLYCOPROTEIN IN PATIENTS WITH CHRONIC HEPATITIS-C VIRUS-INFECTION

The significance of circulating antibody to hepatitis C virus (HCV) en velope glycoprotein 2 (E2)/nonstructural protein 1 (NS1) glycoprotein was studied in 83 patients with chronic HCV infection diagnosed by pol ymerase chain reaction (PCR). E2/NS1 antibody was quantitatively exami ned by a passive hemagglutination test using recombinant E2/NS1 glycop rotein encompassing amino acids 388 to 664 of the HCV-H strain. The re sults were correlated with clinical and virological features such as g enotypes and viremic levels assessed by a competitive reverse-transcri ption PCR assay. E2/NS1 antibody was found in 73 patients (88%), and i ts occurrence was related to viremic levels. ES/NS1 antibody titers we re low in asymptomatic HCV carriers with low levels of viral replicati on; 9 of 17 such patients tested positive for E2/NS1 antibody (53%), c ompared with 64 of 66 chronic hepatitis C patients (97%) (P <.01). A s ignificant direct relationship was observed between viremic levels and EP/NS1 antibody titers (r = .52, P <.01), Of the 13 patients with low viremic levels of <10(6) copies/mL, only 5 tested positive for E2/NS1 antibody (38%), whereas 68 of the 70 patients with viremic levels of greater than or equal to 10(6) copies/mL had it (97%) (P <.01). As for the relation to HCV genotypes, no difference was seen in E2/NS1 antib ody titers among genotypes examined (Ib, 2a, and 2b). These findings s uggest that the E2/NS1 antibody tested exhibits no neutralizing activi ty in chronic HCV infection but may serve as a serological indicator o f active virus replication.