Comparison of radioimmunoassay and counter-immunoelectrophoresis for the detection of antibody to hepatitis B core antigen.

A competitive solid-phase radioimmunoassay (RIA) for antibody to hepatitis B core antigen (anti-HBc) was set up using purified hepatitis B core antigen and 125I-labeled anti-HBc. RIA was compared with counter-immunoelectrophoresis (CIEP) for anti-HBc by examining a panel of quality control sera, clinical specimens screened for evidence of hepatitis B virus infection and sera collected during a VD clinic survey. RIA for anti-HBc was found to be more sensitive and more specific than CIEP. It detected anti-HBc in all HBsAg-positive and in most anti-HBs-positive patients. CIEP for anti-HBc was also positive in almost all HBsAg-positive patients but was frequently negative in anti-HBs-positive patients. Non-specific reactions occurred in both tests but by RIA they could be more easily distinguished from true positives.