Haemagglutination inhibition assay of the common determinants and subspecificities of Australia antigen.

Antigenic determinants of Australia antigen (AuAg) may be determined by haemagglutination inhibition with ease and high sensitivity. The reaction depends on the inhibitory effect of the test antigen-positive sample on the agglutination by specific antibody of glutaraldehyde-fixed sheep erythrocytes which have been tanned and coated with AuAg of different specificities. The standard monospecific antibody reactants are directed against one or other of the common antigens, and , or against the subtypic determinants, and . Because it is more sensitive than conventional immunodiffusion or electrosyneresis, and more convenient than radio-immunoassay, haemagglutination inhibition is most suited to large-scale determinations of AuAg subtypes in samples of relatively low antigenic activity.