Feline oncornavirus-associated cell membrane antigen: evidence for an immunologically crossreactive feline sarcoma virus-coded protein.

Abstract

The feline oncornavirus-associated cell membrane antigen (FOCMA) acts as a target for natural immunosurveillance against tumor development in the cat. In the present study, mink and rat cells nonproductively transformed by feline sarcoma virus (FeSV) expressed FOCMA and 5''-terminal feline leukemia virus (FeLV) gag gene proteins, p15 and p12. Such cells lack detectable levels of other FeLV gag gene-coded proteins or the env gene product, gp 70. FOCMA, p15 and p12 antigen expression is initially in the form of an 80,000-100,000 MW precursor which, upon post-translational cleavage, gives rise to a 65,000 MW component that contains FOCMA and a 25,000 MW component containing p15 and p12. Feline lymphoma cells, including those from several tumors that lacked detectable levels of FeLV structural protein expression, were FOCMA-positive. These findings strongly suggest that FOCMA represents an FeSV-coded transformation specific protein and provide preliminary information regarding the position within the FeSV genome coding for its synthesis.