Competition radioimmunoassay for mason‐pfizer monkey virus: Comparison with recent isolates

The major core protein of Mason‐Pfizer monkey virus was purified by DEAE ion exchange column chromatography and shown to be 27,000 daltons (p27). Following the characterization of monospecific antisera prepared against p27, a radioimmunoassay was developed with these reagents and competition experiments were done with some of the recent M‐PMV‐like isolates as well as with other oncornaviruses. Results suggest that three of the viruses tested, AO, X‐381 and FTP‐1, are similar to M‐PMV while J‐96 virus is related, but not identical, to M‐PMV. It is also shown that competition RIA can be used successfully to detect the presence of viral proteins in tissue homogenates and cell extracts.