Development of a direct-binding enzyme-linked immunosorbent assay as an alternate assay for anti-hepatitis B core

Anti-hepatitis B core (anti-HBc) screening is now used in some countries as a surrogate test to reduce the incidence of posttransfusion non-A, non-B hepatitis. The purpose of this study was to develop and standardize an alternate assay, for the detection of anti-HBc, based on a direct-binding enzyme-linked immunosorbent assay (db-ELISA). Microtiter plates were coated with recombinant DNA hepatitis B core antigen. Patient antibody was detected spectrophotometrically using a goat, anti-human immunoglobulin conjugated with horseradish peroxidase. The db-ELISA was compared to a standard competitive-binding ELISA (cb-ELISA). A competitive-binding radioimmunoassay (cb-RIA) was used as the reference assay for this study. The specificity of the cb-ELISA was 50% and the positive predictive value was 64% when compared to the cb-RIA. The specificity and positive predictive value of the db-ELISA were both 97% when compared to the cb-RIA. Based on titration studies, the sensitivity of the db-ELISA is at least equal to the cb-RIA. Based on the data generated in this study, the db-ELISA appears to be an acceptable screening test for anti-HBc.