A mutant of rous sarcoma virus with a conditional defect in the determinant(s) of viral host range

Abstract

A temperature-sensitive mutant of the Prague strain of Rous sarcoma virus of subgroup C, tsPH734PR-C, replicates much less efficiently at the nonpermissive (41°) than the permissive (35°) temperature while transforming equally well at both temperatures. In contrast, the wild-type parent, wtPR-C, is able to replicate and to transform chick embryo fibroblasts equally well at both 35° and 41°. Two lines of evidence suggest that tsPH734PR-C is defective in the synthesis or utilization of virus envelope glycoproteins GP85 and GP35. First, tsPH734PR-C appears to be defective in the incorporation of the virus envelope glycoproteins GP85 and GP35 into the noninfectious virus particles synthesized at 41°. Second, tsPH734PR-C, a host range subgroup C virus, is not complemented for replication of subgroup C virus at 41° by coinfection of cells with RAV-6 avian leukosis virus of subgroup B or by coinfection with the defective Bryan strain of Rous sarcoma virus, BH-RSV(−).