Feline Leukemia Virus- and Feline Sarcoma Virus-Related Polypeptides Released by Virus Producer and Nonproducer Cells

Abstract

Polypeptides specific for feline leukemia virus (FeLV) have been identified in the media of cells that produce FeLV as well as in nonproducer cells transformed by feline sarcoma viruses (FeSV). Cat fibroblasts that were persistently infected with FeLV release the major virus envelope glycoprotein, whereas cultured cat lymphoma cells shed both glycopeptides related to the virus core gene (gag) and glycopeptides related to the virus envelope gene fenvj. Mink cells and cat cells transformed by FeSV secrete polypeptides of a wide range of sizes that cross-react with the major virus core protein p27. Differences in the classes of p27-related proteins produced may be related to the strain of virus and the cell type. Cat cells transformed by FeSV release a glycopeptide that appears to be processed differently from those identified in the media of FeSV-transformed mink cells. The possibility that such FeLV-related secretory proteins may interfere with the immune response of the host is discussed.