Hepatitis B surface antigen in donated blood--screening and confirmation by enzyme-linked immunosorbent assay.

Principles of and test procedures enzyme-linked immunosorbent assay (ELISA) screening and confirmatory tests for hepatitis B surface antigen (HBsAg) in donated blood are described. The assay is of "third-generation' sensitivity and is practical and economical for large-scale screening of blood donors. Results from 119,000 tests show ELISA to be superior to the passive haemagglutination inhibition (PHAI) test for HBsAg. The ELISA described here is considerably cheaper than any comparable commercially available isotopic kit for HBsAg screening but is slightly less sensitive.