COMPARISON OF 2 2ND-GENERATION ANTI-HEPATITIS-C VIRUS ELISA ON 21431 US BLOOD-DONOR SAMPLES

We have compared two different second-generation (2.0) enzyme-linked i mmunosorbent assays (ELISA) for the presence of antibodies to hepatiti s C virus (anti-HCV) in blood from volunteer, unpaid donors. At two se parate blood centres, a total of 21431 donor samples were tested with Abbott Anti-HCV 2.0 ELISA and Ortho Anti-HCV 2.0 ELISA. Samples found to be repeatedly reactive were tested by supplemental/investigational assays, MATRIX HCV (Abbott) and anti-HCV RIBA II (Ortho/Chiron), to 'c onfirm' the presence of anti-HCV. Discordant ELISA samples were additi onally tested by the polymerase chain reaction (PCR) for the presence of HCV RNA. The Abbott anti-HCV assay had a repeatedly reactive rate o f 0.59% (127/21431) and the Ortho anti-HCV assay 0.51% (110/21431). Ov erall agreement between assays was 99.76%. 72/127 (56.7%) of Abbott re peatedly reactive samples confirmed on MATRIX and 61/127 (48.0%) on RI BAII; 70/110 (63 . 6%) of Ortho repeatedly reactivate samples confirme d on MATRIX and 61/110 (55.5%) on RIBA II, Discordant ELISA samples te sted by PCR yielded negative results. Hence the two ELISA had equal se nsitivity, as defined by detection of true positive samples; the sligh tly lower specificity of the Abbott Anti-HCV 2.0 ELISA may be owing to culling of donors with a false positive test by Ortho's Anti-HCV 1.0 and 2.0 ELISA tests (the routine tests in place at each blood centre). A sample found to be repeatedly reactive by two different ELISA tests for anti-HCV is likely to be a true positive and may not require furt her 'confirmatory' testing.