Serological markers of posttransfusion hepatitis C viral infection.

Serological markers for hepatitis C virus (HCV) infection were measured in serial samples from 14 posttransfusion chronic non-A, non-B hepatitis patients by a semiquantitative dot blot immunoassay. The assay detected antibodies to HCV by use of recombinant proteins that represent putative HCV capsid (core), nonstructural protein 3 (NS3) (33c), and NS4 (c100) epitopes. Seroconversion to anti-HCV antibodies (anti-HCV) was detected in all patients. The average time to active antibody production detected by any of the recombinant proteins was 13.8 (range, 3.6 to 22.0) weeks posttransfusion or 4.6 (range, -4.5 to 13.4) weeks after the first biochemical marker of illness. Anti-HCV were detected earliest by the core antigen in most cases; however, the patterns of anti-HCV responses varied significantly among individuals. Overall, the addition of the core and NS3 antigens to the assay enabled the detection of the antibody response 4 to 5 weeks earlier than did the addition of the c100 antigen, the sole antigen used in current screening tests in the United States. Passively transferred antibodies were detected by at least one antigen in early posttransfusion samples from 12 patients and decayed below detectable levels for all antigens in only 2 patients. Antibodies to all three gene products were evident in the last sample from all five patients monitored for greater than 3 years from transfusion indicating the persistence of antibodies in patients with chronic illness. Our data show that the period following the onset of hepatitis during which anti-HCV are not detected by current screening assays can be greatly shortened by the detection of anti-HCV responses by a combination of core, NS3, and c100 antigens.