Tumor-specific and tumor-associated membrane antigens of rous sarcoma virus transformed hamster fibroblasts

Hamster fibroblasts transformed by an env^-strain of Rous sarcoma virus (RSV) express at their surface tumor-associated antigens of unknown origin and a tumor-specific antigen (VCSA) which is not expressed by hamster fibroblasts transformed by unrelated DNA or RNA oncogenic viruses. This antigen was detectable by rabbit antibodies and a complement-dependent ⁵¹Cr-release cytotoxicity assay and is common to RSV-transformed cells of different animal species. By comparing the anti-VCSA serum with antisera directed against purified gp85, gs-proteins, reverse transcriptase or detergent-lysed virus particles, it was shown that VCSA is not a known virion structural protein. Moreover, VCSA expression does not correlate with viral replication since it is not detectable in chick embryo fibroblasts productively infected with the transformation-defective virus RAV-1 which shares virus structural genes with RSV. Finally, in hamster cells transformed by an RSV mutant, temperature-sensitive for the ability to transform the host cell, VCSA expression at the cell surface correlates with the expression of the transforming gene.