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

Abstract

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 detergentlysed 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.