Changes in antibodies to specific hepatitis C virus antigens with interferon-alpha therapy: analysis by recombinant immunoblot assay.

Antibodies to hepatitis C virus NS3 (C33C), NS4 (5-1-1 and C100-3), and core (C22-3) proteins were tested for by a second-generation recombinant immunoblot assay of serum samples from 42 chronic hepatitis C patients treated with interferon-alpha. Antibodies to 5-1-1 and C100-3 were found in 83% (35/42) before therapy, and those to C22-3 and C33C in all patients. At 6 months after therapy withdrawal in patients with sustained virus clearance, only antibodies to 5-1-1 and C100-3 showed significant decreases (p < 0.05) (5/5 and 7/7, respectively). Antibodies to C22-3 and C33C decreased less frequently in only 11% (1/9) (p < 0.01) and 44% (4/9) (p < 0.05), respectively. Thus, antibodies to 5-1-1 and C100-3 are prone to decrease following a decline in viremia. The antibody to the C22-3 (core) protein was least likely to decrease and may serve as a reliable marker of exposure to the virus.