Immunoblot in the serological diagnosis of hepatitis C virus infection

The objective of the study was to assess three immunoblot assays, the Deciscan HCV Plus, the Riba and the Inno-Lia, on 44 discordant samples with three ETA kits. These immunoblots were considered as confirmation reagents. A result was considered as a false positive by anti-HCV antibody assay if the three immunoblots were negative or if two immunoblots were negative with the third being indeterminate and a negative virogical genomic diagnosis observed on all the samples. The result was positive if at least two immunoblots out of three were positive. Thus, 34 samples were considered as false positive and ten samples were excluded because it was impossible to conclude between true or false positive result. The 44 discordant results were never confirmed as positive by the use immunoblot or PCR. The three immunoblots were negative for half of the samples and two immunoblots and one indeterminate were observed for 77% of the samples. The false positive results by the Monolisa assay were more often found indeterminate with the Deciscan assay than with the other immunoblots. That was also checked for Vitros/Riba pair. One of the explanations could be the use of common antigens for the reagents from the same manufacturer. The Inno-Lia test is the most specific immunoblot according to the results obtained in our study. (C) 2004 Elsevier SAS. Tous droits reserves.