Characterization of tumor-specific transplantation antigen induced in cells infected or transformed by polyomavirus

Tumor-specific transplantation antigen (TSTA) activity was investigated (with the use of inbred BALB/c and C3H mice and inbred Fisher and Wistar rats) in various early polyomavirus (Py)-coded proteins by three methodologies: 1) immunoprecipitation by anti-T-antigen sera, gel slicing, and immunization; 2) affinity chromatography with the use of anti-tumor-associated antigen serum; and 3) use of a Py mutant, NG18. The results obtained by all three techniques allowed refutation of the hypothesis that the three major species of T-antigen possess the main TSTA activity, particularly middle-sized T-antigen which is a plasma membrane protein. TSTA activity was found to be associated with proteins having a molecular weight of approximately 37,000. The exact origin of this protein is discussed.