Temperature-sensitive conditional-lethal mutants of reovirus 3: I. Isolation and characterization

Abstract

Six temperature-sensitive mutants of reovirus 3 have been identified among 162 plaque isolates tested. Two of these ts mutants arose spontaneously, two from virus exposed to nitrous acid, and two from virus grown in the presence of 5-fluorouracil. Optimal temperature of growth for four of the ts mutants was 30°, and for two was 33°. The optimal temperature for growth of wild-type virus, 37°, was nonpermissive for all of the six ts mutants. The temperature sensitivity was found not due to inactivation at 37° of the ts mutant virus particles, but was due to some temperature-sensitive step occurring late in viral growth. On the basis of differential thermosensitivity at 52°, the ratio of infectivity to hemagglutinating activity, and responses in temperature-shift experiments, the six ts mutants have been classified in two groups.