A single peptide derived from the sequence common to polyoma small and middle T-antigen induces immunity against polyoma tumors.

Polyoma virus, an oncogenic virus, fails to induce tumors in immunocompetent rodents due to T cell-dependent mechanisms. The target recognized by the immune system has been functionally defined as polyoma tumor-specific transplantation antigen (TSTA) and has been postulated to be related to the virus three early proteins small T (ST), middle T (MT), and large T (LT) antigens. We show here that immunization with a synthetic peptide corresponding to amino acids 162-176 of polyoma MT and ST was able to decrease tumor progression of polyoma tumors, but not of nonpolyoma tumors. This indicated that these amino acids constitute an epitope of the polyoma tumor-specific transplantation antigen.