Hepatitis C virus RNA and hepatitis C virus antibody in the serum of patients with abnormal liver function.

In order to elucidate the relation between hepatitis C virus (HCV) RNA and antibody to HCV (anti-HCV) in serum, we examined samples of serum collected from 228 HBsAg-negative patients, with abnormal alanine aminotransferase (ALT) values, for HCV-RNA by nested polymerase chain reaction (PCR) assay and for anti-HCV using C100 protein as the antigen. HCV-RNA was detected in 99 (92.5%) of 107 anti-HCV-IgG-positive samples, regardless of ELISA optical density cut-off value (ELISA ratio), and in 34 (28.1%) of 121 anti-HCV-IgG-negative samples in which the frequency of the presence of HCV-RNA became higher in proportion to the ELISA ratio. Among 42 discordant cases (34 anti-HCV-IgG-negative, RNA-positive cases and eight anti-HCV-IgG-positive, RNA-negative cases), 10 were positive for anti-HCV-IgM (8/34 and 2/8, respectively) irrespective of clinical status. These findings suggest that in patients with abnormal ALT values, even if they are anti-HCV-IgG negative, HCV infection cannot be excluded. Furthermore, PCR assay for detecting HCV-RNA may be more suitable for identifying patients with infectious virus than is detection of anti-HCV-IgG. Detection of anti-HCV-IgM may also be useful.