IgM-antibody response to hepatitis C virus antigens in acute and chronic post-transfusion non-A, non-B hepatitis

A specific IgM solid-phase enzyme-linked immunoassay for the diagnosis of a recent infection by hepatitis C virus (HCV) was developed. The assay utilizes a structural antigen encoded by sequences at the 5' end of HCV (core region) and non-structural (NS) antigens encoded by the NS-3 (33c) and NS-4 (c100-3) regions of the HCV genome. Serial serum samples from several clinically diagnosed post-transfusion non-A, non-B hepatitis patients were analyzed for anti-HCV IgM. This antibody was frequently but transiently detected. Anti-HCV core IgM was more frequently detected than anti-c100-3 or anti-33c IgM. In individuals who resolved their HCV infection or progressed to chronicity, anti-HCV IgM was produced transiently at or near the onset of clinically diagnosed acute hepatitis.