IgM antibody response to the hepatitis C virus core protein in intravenous drug users.

Abstract To verify whether a solid-phase enzyme immunoassay for serum IgM antibodies to the hepatitis C virus (HCV) core protein (IgM anti-HCVcore) might be proposed as a surrogate test for serum HCV RNA, we studied 86 anti-HCV antibody-positive intravenous drug users. Serum HCV RNA was demonstrated by RT-PCR with primers derived from the 5′ noncoding and the core region. IgM anti-HCVcore antibodies were found in 62/86 (72%) subjects; circulating HCV RNA was detected by the 5′ noncoding assay in 53/86 samples (62%) and by the core region assay in 35/86 samples (41%). IgM anti-HCVcore reactivity was associated with core HCV RNA seropositivity ( p p = NS). Patients infected by HCV type 1a were more-often positive for IgM anti-HCVcore ( p p = 0.005) than patients infected by other HCV genotypes. IgM anti-HCVcore reactivity was significantly more common in subjects positive for core HCV RNA ( p 30 years ( p