Hepatitis C virus RNA in blood donor sera detected by the polymerase chain reaction: Comparison with supplementary hepatitis C antibody assays

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Abstract
The low specificity of screening ELISAs for antibodies to hepatitis C virus in blood donors has called for confirmatory tests. Two types of supplementary antibody assays are available, recombinant immunoblot assays (RIBA‐1 and RIBA‐2) and an antibody consumption test referred to as a neutralization assay. Amplification of viral nucleic acid by the polymerase chain reaction (PCR) provides an antibody independent mode of detecting viral infection. We applied reverse transcription‐double PCR to detect an HCV 5'‐noncoding viral RNA sequence in serum specimens and compared PCR findings with confirmatory antibody tests. This study includes sera from 37 blood donors found positive by the Ortho anti‐HCV (C100‐3) ELISA out of 14,591 donations. Of the 37 positive sera, 8 were positive by RIBA‐1 and 1 further by RIBA‐2. Seven of the RIBA positive sera contained HCV RNA by PCR. Among the 8 indeterminate and the 21 negative donor sera by RIBA‐I, no PCR positive serum was found. The 37 anti‐HCV positive donor sera identified by Ortho ELISA were also tested by Abbott anti‐HCV (C100‐3) ELISA whereby 22 were positive. Of these 22 sera plus 1 further with ELISA OD just below cutoff, 8 were positive by the “neutralization assay,” (Abbott Laboratories, North Chicago, IL, USA) and 6 of these, including the borderline serum, were PCR positive. One of the two neutralizable but PCR negative sera was RIBA positive and the other was indeterminate. However, one ELIS. A (Abbott Laboratories) positive (OD 1.99) serum was not neutralizable but nevertheless contained HCV RNA by PCR. Thus in blood donor sera, anti‐HCV (C100‐3) reactivity confirmed by RIBA or “neutralization” correlated well with the presence of HCV RNA.