In Germany, transmission of hepatitis C virus by blood transfusion is prevented by screening the donations for anti-HCV and ALT. The specificity of the anti-HCV screening in low seroprevalence populations has been questioned. In order to evaluate this screening policy we wanted to estimate the prevalence of viremic and potentially infectious donors by the HCV-RNA polymerase chain reaction (PCR) in our donor population of southern Germany. Donors (n = 301) were divided into four subgroups according to anti-HCV status and ALT levels. HCV sequences were detected by nested PCR, using primers for the most conserved region of the viral genome. The recombinant immunoblot assay (RIBA-4) was applied to the same samples. PCR detected 4.2% HCV-RNA carriers in the subgroup anti-HCV-/ALT-; 3% in the subgroup anti-HCV-/ALT+; 19.4% in the subgroup anti-HCV+/ALT-; and 59.4% in the subgroup anti-HCV+/ALT+. It was concluded that, on the one hand, the lack of specificity of the anti-HCV ELISA gives rise to many false-positive results; on the other hand, a minority of infected donations will not be detected by the screening procedure. ALT in conjunction with anti-HCV improves the quality of screening for potentially infectious donors.

In this study we tested the seroreactivity of 223 selected anti-HCV-reactive blood donors to the human B-cell epitope N-VYLLPR-C (C34-39) of the hepatitis C virus core antigen. The epitope was recently identified and characterized by the human monoclonal IgG antibody Ul/F10 and is located within the amino acid residues 34-39 of the aminoterminal core region. The blood donor sera were selected from anti-HCV ELISA (Ortho, 2nd generation)-reactive samples. Sixty-seven of these sera were further reactive in RIBA (Ortho, 2nd generation). According to their RIBA pattern, these samples were divided into four groups. Samples in the first group (n = 18) reacted to all four recombinant HCV antigens. The samples of the second (n = 9) and third group (n = 8) reacted to c22-3/c33c and c22-3/c100-3, respectively. Sera from group 4 (n = 32) showed a RIBA indeterminate pattern with reactivity only to c22-3. All 223 samples were analyzed for anti-C34-39 antibodies by ELISA, and the 67 RIBA-reactive samples were additionally tested for the presence of HCV RNA by RT/PCR. In groups 1 and 2, over 80% of the samples showed anti-C34-39 reactivity which was restricted to the IgG1 isotype. In contrast, in groups 3 and 4, antibodies to the epitope C34-39 were detected in less than 10% of the samples. Interestingly, the anti-C34-39 response correlates with the presence of HCV RNA; 95.5% of the samples had coincident results in all subgroups. None of the RIBA-negative sera showed a specific seroreaction to the C34-39 peptide.

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