Interferon (IFN) alfa has been used widely for the treatment of chronic hepatitis C virus (HCV) infections but only a small number of patients treated have shown a sustained biochemical and virological response. Anti-envelope E1 and E2 antibody titers were assessed retrospectively before, during, and after treatment with IFN in order to evaluate their usefulness for the prediction and monitoring of therapy outcome in 115 patients infected chronically with HCV genotype 1b. At baseline, E2 induced more frequent and stronger immunogenic responses than E1, irrespective of patient response to therapy. E1 and E2 antibodies also tended to be higher in patients with a long-term or a transient response to IFN treatment than in patients who were absolute non-responders. In most patients, E1 and E2 antibody levels tended to be lower after treatment. This reduction was most pronounced and occurred most frequently in long-term responders to therapy. In this patient group, the reduction of E1 antibodies was more pronounced than that of E2 antibodies. In contrast to E2 antibodies, the decrease of E1 antibodies could already be observed at the end of therapy (week 24) and was significantly larger (p<0.05) than that observed in relapsers and non-responders. Thus, a sustained elevation of E1 antibodies seems to be associated with ongoing infection even when HCV RNA levels were undetectable in serum. Monitoring of E1 antibody titers may represent a useful additional marker to discriminate sustained responders from those who relapse in patients receiving interferon therapy.

Interferon (IFN) alfa has been used widely for the treatment of chronic hepatitis C virus (HCV) infections but only a small number of patients treated have shown a sustained biochemical and virological response. Anti-envelope E1 and E2 antibody titers were assessed retrospectively before, during, and after treatment with IFN in order to evaluate their usefulness for the prediction and monitoring of therapy outcome in 115 patients infected chronically with HCV genotype 1b. At baseline, E2 induced more frequent and stronger immunogenic responses than E1, irrespective of patient response to therapy. E1 and E2 antibodies also tended to be higher in patients with a long-term or a transient response to IFN treatment than in patients who were absolute non-responders. In most patients, E1 and E2 antibody levels tended to be lower after treatment. This reduction was most pronounced and occurred most frequently in long-term responders to therapy. In this patient group, the reduction of E1 antibodies was more pronounced than that of E2 antibodies. In contrast to E2 antibodies, the decrease of E1 antibodies could already be observed at the end of therapy (week 24) and was significantly larger (p<0.05) than that observed in relapsers and non-responders. Thus, a sustained elevation of E1 antibodies seems to be associated with ongoing infection even when HCV RNA levels were undetectable in serum. Monitoring of E1 antibody titers may represent a useful additional marker to discriminate sustained responders from those who relapse in patients receiving interferon therapy.