Safer blood--supplementation of blood products with anti-HBs.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantitation of antibodies (anti-HBs) to the surface antigen of the hepatitis B virus (HBsAg). The ELISA uses HBsAg as the solid phase, and, after conjugation to horseradish peroxidase, also as the conjugate. Conditions for this assay were optimized and a rapid (1.5 hours) ELISA has evolved which works very satisfactorily for the large-scale screening of donated blood. We have used this ELISA to examine donated blood in Natal and concluded that we cannot initiate a programme of anti-HBs supplementation of parenteral blood products without hyperimmunization and plasmapheresis of selected, voluntary donors.