Evaluation of performance of the RIBA processor system for automated analysis of the strip immunoblot assay for detection of antibodies to hepatitis C virus.

The performance of a new automated analyzer for the processing and interpretation of the RIBA Strip Immunoblot Assay (SIA), used in the diagnosis of hepatitis C virus (HCV) infection, was evaluated. Laboratory performance of the RIBA SIA was compared with that of two manually processed supplementary anti-HCV tests (RIBA HCV 3.0 SIA and INNO-LIA HCV Antibody III). Specificity of the automated processing of SIA was 100% for 90 selected anti-HCV-negative samples. On the other hand, 119 of 120 (99.2%) previously confirmed anti-HCV-positive samples were also positive when assayed on the automated processor. Results for all specimens except one (51 of 52) were concordant for manual and automated RIBA, while 15 of 68 sera tested with automated RIBA and the INNO-LIA assay showed different patterns of reactivity. Three HCV sensitivity panels and one seroconversion panel were also compared. The results show a high sensitivity for SIA NS3- and NS5-encoded antigens. Moreover, data obtained for the anti-HCV seroconversion panel and for samples with borderline or discordant anti-HCV enzyme-linked immunosorbent assay results suggest that bands with a relative intensity of >0.5 on the automated analyzer (theoretically negative) should be evaluated with care. Coefficients of variability ranged from 9 to 14.8% in an interassay reproducibility study. Overall, the performance of the automated analysis of SIA is comparable to that of the manual RIBA assay. The new automated processor for SIA bands proved to be sensitive and specific. Its use makes the optical scoring of bands unnecessary by indicating relative intensity values, which could be particularly useful in the follow-up care of anti-HCV-positive patients receiving antiviral therapy.