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BACKGROUND: The detection of hepatitis C virus (HCV) infection is of major importance for the prevention of transfusion-transmitted hepatitis. The testing of donations by nucleic acid testing (NAT) techniques may not be feasible or economic. Combined antigen and antibody assays are now available, and the performance of two combined assays on window-phase donations is evaluated.

STUDY DESIGN AND METHODS: Three panels of antibody-negative plasma samples from HCV NAT-only–positive donors were characterized for HCV status by quantitative reverse transcription–polymerase chain reaction, a commercial third-generation HCV antibody assay (Ortho), and combined antigen and antibody assays (Bio-Rad MONOLISA and Murex).

RESULTS: All 142 plasma samples were antibody negative by Ortho third-generation HCV. A total of 112 samples (79%) were found to contain HCV RNA; 32 were detected by the Bio-Rad assay (29%), whereas 56 (50%) were detected by the Murex assay. Of 45 samples with viral loads of greater than 106, 32 (71%) were positive in the Bio-Rad combination assay and 44 (98%) were positive in the Murex assay. Interestingly none of the 3a genotypes were detected by the Bio-Rad MONOLISA, including eight donations that were greater than 106 IU per mL.

CONCLUSIONS: Combined antigen and antibody testing provides a useful improvement on the sole reliance on antibody testing for detection of HCV infection; however, it remains less sensitive than NAT for detecting viremic donors and may be genotype susceptible.