Efficacy of a hepatitis C virus core antigen enzyme-linked immunosorbent assay for the identification of 'window-phase' blood donations

Background and Objectives Recent studies have suggested that potentially in fectious donations provided during the antibody-negative 'window' phase of hepatitis C virus (HCV) infection may be identified by testing for viral RN A or HCV core protein. We therefore evaluated the performance of an HCV ant igen enzyme-linked immunosorbent assay (ELISA) for identification of window -phase donations and for prospective screening of blood donors. Materials and Methods One-hundred and twenty-eight archived plasma donation s containing HCV RNA, but lacking antibody to HCV (anti-HCV), were tested b y using the HCV antigen ELISA, together with 9951 freshly collected serum a nd plasma specimens from blood donors. Results HCV core antigen was detected in 94% (120/128) of window-phase plas ma donations. Overall specificity in freshly collected blood donor specimen s was 99.74%. Two putative window-phase donations containing HCV core prote in and viral RNA were identified from paid plasma donors by prospective tes ting with the HCV antigen ELISA. Conclusion These results indicate that an HCV antigen ELISA can identify al most all (94%) of viraemic donations given during the seronegative window p hase of infection. The performance of the HCV antigen ELISA appears to be s uitable for large-scale screening of blood donations.