Immunological properties of two polypeptides of Mason-Pfizer monkey virus.

Two polypeptides were isolated from the Mason-Pfizer monkey virus (MP-MV). The polypeptides, designated MP-MV p26 and MP-MV p15, were 26,000 and 15,000 molecular weight, respectively, based on gel filtration chromatography in the presence of 6 M guanidine hydrochloride. Radioimmunoassays developed for MP-MV p26 and p15 were, respectively, 10 and 100 times more sensitive than immunodiffusion and 1 and 10 times more sensitive than micro-complement fixation for the detection of MP-MV. Antigens of other reverse transcriptase-containing RNA viruses did not cross-react in either MP-MV radioimmunoassay. Further, antisera against these other viruses did not react with the radioiodine-labeled MP-MV polypeptides. The MP-MV radioimmunoassays should be useful in studying the natural occurrence of this virus and its relationship to primate tumors.