CONFIRMATION OF HEPATITIS-C VIRUS-ANTIBODY IN BLOOD-DONORS

Of 103,203 donations collected in Scotland and Northern Ireland over a 3-month period and screened for HCV antibody by Ortho or Abbott secon d-generation ELISAs, 340 were found repeatedly reactive. Supplementary testing with RIBA-2 resulted in 77 being classified as positive, 130 as indeterminate, and 133 as negative. PCR analysis of the positives a nd indeterminates indicated viraemia in 65 (84%) of the positives and 7 (5.5%) of the indeterminates. To determine if PCR analysis could be eliminated or reduced by further serological testing, all RIBA-2 posit ives and indeterminates were tested by UBI and Wellcozyme ELISAs and I nnolia and RIBA-3 immunoblots. All RIBA-2 positives with bands to more than 1 gene product were detected in all 4 systems, but >60% of RIBA- 2 indeterminates were negative in those tests that contain either reco mbinant antigens or synthetic peptides derived independently from thos e used by Ortho/Abbott tests. A comparison of data from the 79 reactiv e with the core (c22) region revealed only 16 samples reactive in all 4 systems as well as Ortho and Abbott. These 16 included all 6 of the PCR positives in the 79 c22 indeterminate samples. ELISAs and immunobl ots using independently derived antigens can offer a useful method of screening out nonspecific reactions in Ortho or Abbott ELISAs, hence r educing the need for PCR testing. Some caution is required as all such tests do not contain identical mixes of antigenic material. (C) 1993 Wiley-Liss, Inc.