Biochemical and immunological characterization of polyproteins coded for by the McDonough, Gardner-Arnstein, and Snyder-Theilen strains of feline sarcoma virus

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Abstract
The McDonough (SM), Gardner-Arnstein (GA) and Synder-Theilen (ST) strains of feline sarcoma virus (FeSV) code for high-MW polyproteins that contain varying amounts of the amino-terminal region of the FeLV [feline leukemia virus] gag gene-coded precursor protein and a polypeptide(s) of an undetermined nature. The SM-FeSV primary translational product is a 180,000 dalton polyprotein which is immediately processed into a highly unstable 60,000 dalton molecule containing the p15-p12-p30 fragment of the FeLV gag gene-coded precursor protein and a 120,000 dalton FeSV-specific polypeptide. The GA- and ST-FeSV genomes code for polyproteins of 95,000 and 85,000 daltons, respectively, which, in addition to the amino-terminal moiety (p15-p12 and a portion of p30) of the FeLV gag gene-coded precursor protein, contain FeSV-specific polypeptides. The GA- and ST-FeSV polyproteins appear to be relatively stable molecules (half-lives of around 16 h) and are not significantly processed into smaller polypeptides. Immunological and biochemical analysis of each of the above FeSV translational products revealed that the sarcoma-specific regions of the GA- and ST-FeSV polyproteins are antigenically cross-reactive and exhibit common methionine-containing peptides. These sarcoma-specific polypeptides are probably coded for by the similar subsets of cellular sequences incorporated into the GA- and ST-FeSV genomes during the generation of these transforming agents.