Comparison of enzyme immunoassay with radioimmunoassay for the detection of antibody to hepatitis B core antigen as the only marker of hepatitis B infection in a population with a high prevalence of hepatitis B.

Enzyme immunoassay (EIA) and radioimmunoassay (RIA) for the detection of antibody to hepatitis B core antigen (anti-HBc) were compared using serum specimens from Alaska Natives screened during a hepatitis B control program that were initially positive by EIA for only anti-HBc. Of 36 specimens from persons previously HBsAg positive but who were now only anti-HBc positive by EIA, 94.4% were anti-HBc positive by both assays, with anti-HBc levels exceeding 93% inhibition. Low-level antibody to hepatitis B surface antigen (anti-HBs) (less than 10 SRU) and antibody to hepatitis Be (anti-HBe) were also present in 50% and 48% of specimens positive for anti-HBc, respectively. Of 148 specimens from persons initially positive for only anti-HBc by EIA who had no previous documentation of any hepatitis B virus (HBV) infection, 64.5% were positive by repeat testing for anti-HBc by both assays, and anti-HBc levels in this sample exceeded 70% in 91.6% and 80.2% of specimens by EIA and RIA, respectively. Low-level anti-HBs and anti-HBe were present in 45.8% and 15.6%, respectively. EIA detection of anti-HBc was found to be less specific than RIA. Of specimens positive for anti-HBc by EIA, 14.8% were negative by RIA. The specificity of the EIA could be improved with respect to RIA by increasing the cut-off from 48% to 68%.(ABSTRACT TRUNCATED AT 250 WORDS)