Target antigens for antibodies and complement at the cell surface of RSV-transformed fibroblasts.

Using cells transformed by Rous sarcoma virus (RSV), an RNA tumour virus whose genetic and structural composition is fully known, the virus-induced surface antigens acting as targets for antibodies and complement were studied. Among the virus structural proteins, only the envelope antigen gp85, but not the core group-specific proteins or reverse transcriptase, were able to mediate immune lysis in the 51Cr-release assay. The group-specific antigenic determinants of gp85 were predominantly involved. The virus-induced cell surface antigen (VCSA), specific for transformation, was the only other molecule effective. Since different cells express either of these antigens, further support is given to the non-identity of virus structural antigens and VCSA.