Evaluation of assay methods for hepatitis B surface (HBsAg) antigen and its antibody (anti-HBs) in viral hepatitis B (VHB)-HBsAg-positive

The sensitivity of methods for the detection of HBsAg and its anti-HBs was compared in serial 1200 sera samples from 30 patients with VHB-HBsAg-positive. HBsAg was tested by gel-diffusion (GD), counter-immunoelectrophoresis (CIE), reversed haemogglutination (rHA), redioimmunoassay (RIA), and enzyme immunoassay (EIA). RIA and EIA methods are statistically significantly more sensitive compared with the other methods (P less than 0.0005). By these methods the minimal concentrations of HBsAg in sera can be proved. Although there is no statistically significant difference in the sensitivity between RIA and EIA, the latter is more sensitive if the subtype ay-HBsAg is considered (12 sera samples). In 24 patients the subtype was ay, in two ad, and in four it could not be differentiated. In 70% of patients anti-HBs was proved by RIA and in 10% by CIE, i.e., in 73% and 9% of sera samples, respectively. In 117 sera samples of these patients the sensitivity of RIA and EIA was compared for determination of anti-HBs. No statistically significant difference between the methods for determination of anti-HBs was found (50.42%: 40.17%). No immune response to HBsAg has been observed in 9 cases, but 6 of them have remained permanent carriers of this antigen.