LACK OF CORRELATION BETWEEN DIFFERENT HEPATITIS-C VIRUS SCREENING ANDCONFIRMATORY ASSAYS

Numerous 2nd and 3rd generation screening and confirmatory assays for the detection of anti-HCV antibodies have been introduced on the inter national market. The aim of the present study was to compare the perfo rmance of five different commercially available screening assays and f our 'confirmatory' assays in a panel of serum samples that had tested positive or borderline with a 2nd generation EIA (Abbott HCV EIA 2nd g eneration), Considerable discrepancies were observed between the diffe rent screening assays and confirmatory tests. The antigens from the pu tative 'core' region of HCV were recognized most frequently by the con firmatory assays. By considering the reactivity to either NS5 (RIBA II I and Inno-LIA) or E2/NS1 antigens (Inno-LIA Ab III) no sample could b e identified as anti-HCV positive that would otherwise have been regar ded as borderline or negative according to its banding pattern with co re, NS3 and NS4 proteins. All 24 HCV-RT-PCR positive samples were anti -HCV reactive by the screening EIAs but only 18 and 21 samples were co nfirmed anti-HCV positive with the RIBA II and III, respectively. A cl ear association was observed between HCV-RNAemia in serum samples and index values (O.D. sample/O.D. cut-off) of the screening EIAs as well as with the number of reactive proteins in the confirmatory assays. In conclusion, the results of current screening and confirmatory assays are highly divergent. The additional diagnostic significance of the re latively expensive and labour-intensive immunoblots appears to be very limited. For the serological diagnosis of HCV infection and for blood donor screening, confirmatory assays should only be used if there is a borderline result by HCV EIA. The determination of infectivity by qu alitative PCR and the follow-up of patients undergoing IFN therapy by HCV-RNA quantification appears to be much more useful.