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.

In our studies on a possible role of type C oncoviruses in human leukemia we applied the technique of cocultivation of human bone marrow with an animal indicator cell line. Dog thymus A7573 cells were cocultivated with human bone marrow samples from normal individuals, leukemic patients, and nonleukemic patients. By means of the indirect cytoplasmic immunofluorescence assay (IFA), antigens which crossreacted with the major internal protein (p30) of the woolly monkey (simian) sarcoma leukemia virus (SiSV) complex could be detected (Nooter et al. 1979). In the case of childhood leukemia, five out of nine cocultures showed virus-related IFA staining.