Detection of antibody to hepatitis B core antigen (anti-HBc) using a direct (antiglobulin) format and development of a confirmatory assay for anti-HBc

A direct (antiglobulin) solid-phase enzyme immunoassay for the detection of antibody to hepatitis B core antigen (anti-HBc) is described. The assay utilizes recombinant hepatitis B core antigen as the solid-phase 'capture' reagent and a mixture of monoclonal antibodies specific for human IgG and IgM conjugated to horseradish peroxidase as the 'detector' reagent. The direct assay demonstrated excellent sensitivity and specificity when compared with a commercially available competitive enzyme immunoassay. The direct assay format lends itself to a confirmatory assay for anti-HBc by addition of monoclonal anti-HBc to the reaction mixture. Feasibility of the confirmatory assay for anti-HBc was demonstrated using specimens reactive for anti-HBc as documented by both the direct and competitive assays.