Detection of hepatitis C virus by PCR in second-generation enzyme immunoassay-seropositive blood donors by using matched pairs of fresh frozen plasma and pilot tube sera

Between April 1993 and March 1995, 429 of 334,454 (0.13%) blood donations at the Toronto Centre of the Canadian Red Cross were reactive for hepatitis C virus (HCV) by second-generation enzyme immunoassay (EIA-2). Of the 429 EIA-2-positive donations, 189 (44%), 138 (32%), and 102 (24%) were positive, indeterminate, and negative by Second-Generation Recombinant Immunoblot Assay (RIBA-2). To assess HCV viremia and minimize the risk that specimen handling affected PCR-based detection, the qualitative AMPLICOR HCV test was performed on both pilot tube sera (PTS) and the corresponding fresh frozen plasma (FFP) from 294 EIA-2-reactive donations. AMPLICOR PCR results for PTS and FFP were 100% concordant and were confirmed by nested HCV PCR for 27 of 294 donations. The AMPLICOR HCV test was positive for 127 of 140 (91%) of RIBA-2-positive donations (81, 91, and 96% of donations with two, three, and four reactive bands, respectively), 5 of 88 (5.7%) indeterminate donations, and 0 of 66 (0%) RIBA-2-negative donations. The Third-Generation Recombinant Immunoblot Assay (RIBA-3) was performed on RIBA-2-negative, -indeterminate, and -positive, PCR-negative donations. RIBA-3 demonstrated enhanced specificity and resolved 18 of 88 (20%) of RIBA-2-indeterminate samples as HCV antibody positive. The study demonstrates that PTS are as suitable as FFP for PCR-based detection of HCV and can be used to determine if EIA-2-reactive blood donors are viremic at the time of donation.