Hepatitis C virus replication and antibodies to structural and nonstructural viral proteins in chronic hepatitis C.

The correlation between hepatitis C virus replication and antibodies to both structural (core) and nonstructural (C100-3) hepatitis C virus proteins (anti-HCVcore and anti-C100-3, respectively) was assessed. The concentration of serum hepatitis C virus RNA was determined by a competitive reverse transcription-polymerase chain reaction assay, and antibody titers were determined by endpoint dilution. No correlation was found between viremic levels and antibody titers in 42 chronic hepatitis C patients. At the end of a 6-month course of interferon-alpha therapy, 18 patients became negative for hepatitis C virus RNA. In the other 24 patients, post-treatment viremic levels ranged from 10(-6.5)-10(0.5) of pretreatment levels. Both anti-C100-3 and anti-HCVcore frequently decreased in patients whose viremic levels dropped to the negative range or to < 10(-2) of pretreatment levels. Anti-C100-3 decreased in all such cases (25/25), while anti-HCVcore decreased in 18/25 (72%) (p < 0.01), indicating that anti-C100-3 is more likely to decrease following suppression of viral replication than anti-HCVcore. These data suggest that hepatitis C virus antibodies may serve as a marker of suppression of viremia following interferon therapy even in patients who do not clear the virus.