Rapid detection of HBsAg and anti-HBs by enzyme-immunoassay.

Enzyme-immunoassay (EIA) for HBsAg is a reliable method with third generation sensitivity. Using a mechanized system for washing and reading and computerized data processing, subnanogramme amounts of subtypes ad and ay could be detected in approx. 5.5 h. Using EIA-kit reagents and an HGsAg 'standard', anti-HBs could conveniently be detected. Sensitivity comparisons with dilution series of the WHO anti-HBs standard showed RIA to be 8--128 times more sensitive than EIA for anti-HBs. However, similar percentages of positives were found in a patient population, and discrepancies were found between RIA and EIA results which cannot be explained on the basis of sensitivity differences only. A careful examination of the specificity of EIA and RIA is indicated.