Retrovirus-encoded transformation-specific polyproteins: expression coordinated with malignant phenotype in cells from different germ layers.

Abstract

A transformation-associated polyprotein designated "gag-x" was previously shown to be induced by the feline sarcoma virus (FeSV) after the nonproductive transformation of rat or mink cells. We found that this protein was also expressed in cells derived from the native species (cat) with or without the production of feline leukemia helper virus (FeLV) and that cats could mount a humoral antibody response to the transformationspecific (x) portion ofthe molecule. Such antisera also reacted with the feline oncornavirus-associated cell membrane antigen (FOCMA) by membrane immunofluorescence. Expression of the gag-x protein was coordinated with malignant phenotype in that both transformed cat fibroblasts and cultured cells from a FeSV-induced melanoma expressed antigenically indistinguishable proteins of the same size. These cells are derived from different embryonic germ layers, suggesting that such transformation-related proteins may function in a pleiotropic manner when introduced by a virus.

Cellular immune response in the blood of cats is restricted to autochthonous feline sarcoma virus‐transformed cells

“…Testicular fibroblasts from five cats were cultured and transformed with a preparation of ST-FeSV containing the helper virus FeLV. It has been shown that FeLV structural proteins are immunogenic in cats (Hardy, 1980;Lee et al, submitted for publication 1983) as are the fusion protein products of the FeSV genome (Chen et al, 1981). Following two immunizations, serum from each of the cats contained antibodies which recognized the gag-fes protein (p85) (data not shown).…”