Detection of human antibodies to hepatitis B surface antigen (HBsAg) by an enzyme-immunoassay for HBsAg.

We studied the feasibility of detecting antibody to hepatitis B surface antigen (anti-HBs) by an inhibition assay using the reagents of an enzyme-immunoassay for HBsAg (Hepanostika). Several modifications of the basic assay were investigated. Sensitivity was greatest when the test sample was incubated with a predetermined amount of HBsAg before the usual procedure of HBsAg detection. The presence of anti-HBs in the test sample was shown by a reduction of the solid-phase bound enzyme label. Results were obtained with a dilution series of serum samples containing anti-HBs, the anti-HBs Reference Panel of the American Bureau of Biologics, sera of hepatitis B patients, and sera of two individuals passively immunised with anti-HBs. The enzyme-immunoassay method showed at least the same sensitivity as passive haemagglutination. It was less sensitive than a commercially available radioimmunoassay (Ausab). There are no indications that non-specific reactions occur frequently. This study also revealed that the antigenaemia of acute hepatitis-B patients can be interrupted by a transient seroconversion.