Analysis of ELISA hepatitis C virus-positive blood donors population by polymerase chain reaction and recombinant immunoblot assay (RIBA). Comparison of second and third generation RIBA.

A new RIBA-3 (Chiron-Ortho Diagnostic System) was performed for discriminating uninterpretable results of RIBA-2. Recognition of antibodies to hepatitis C virus by RIBA-2 and RIBA-3 was compared among 95 ELISA-2 (second generation ELISA) positive blood donors and correlated with alanine-aminotransferase (ALAT) levels and viremia, using polymerase chain reaction (PCR). These studies led to three important conclusions. First, all ELISA-2-positive, RIBA-2-positive and ALAT-positive samples were found viremic compared with 73% of ELISA-2-positive, RIBA-2-positive and ALAT-negative samples. Then, the comparison of the different RIBAs allowed to conclude that RIBA-3 was more sensitive but less specific than RIBA-2. RIBA-3 was interesting to discriminate undetermined RIBA-2, owing to an improved specificity of C100-3 antigen. In fact, most of the C100-3 positive, RIBA-2 undetermined samples became RIBA-3 negative whereas C22-3 positive, RIBA-2 undetermined samples became RIBA-3 positive or undetermined. Finally, a significant correlation was found between the presence of antibodies against C33-c antigen and viremia.