Biological properties and translational products of three independent isolates of feline sarcoma virus

Abstract

Three transforming retroviruses have been isolated from naturally occurring tumors of outbred cats. In the present report, the biological properties of the SM, GA, and ST strains of feline sarcoma virus (FeSV) have been characterized in tissue culture. Like previous mammalian transforming viruses, each FeSV strain was demonstrated to be replication defective, requiring a type-C RNA virus as a helper. Reproducible differences were demonstrated in the morphology of transformed foci induced by each FeSV strain. These findings were independent of helper virus or assay cell utilized, suggesting that the transforming activities of the three FeSV strains are distinguishable. Nonproducer transformants of SM-FeSV expressed feline leukemia virus (FeLV) gag gene products, p15, p12, and p30. In contrast, the GA-and ST-FeSV genomes coded only for p15 and p12 proteins, further distinguishing SM-FeSV from the other FeSV strains. Each remained stable with respect to viral protein expression upon transmission to new cells, demonstrating the stable association of FeLV gag gene information with each FeSV genome. Analysis of the FeLV structural proteins translated in nonproducer transformants of the three FeSV strains revealed the presence of precursor molecules, whose sizes could not be accounted for solely by the number of FeLV gag proteins present in them.