A competition immunoprecipitation assay of unlabeled poliovirus antigens.

An assay method is described for unlabeled, unpurified N(ative) and H(eated) antigens of poliovirus. The method is based on competition between the unlabeled antigen and a standard quantity of radiolabeled antigen, in the presence of a limiting amount of a N- or H-specific, monoclonal antibody. The immune complexes are removed by protein A-bearing, fixed staphylococci. The method is free from cross-reaction between N and H antigen, and has a detection limit of approximately 2 nM. It was applied successfully to the quantitation of poliovirus antigen synthesized by recombinant yeast expressing the viral proteins P1 and 3CD.