Characteristics of an influenza mutant temperature-sensitive for viral RNA synthesis

Abstract

A ts mutant of fowl plague virus has been isolated after mutagenesis with 5-fluorouracil, which is temperature-sensitive in viral RNA synthesis. By temperature shift experiments it was demonstrated that the synthesis of viral particle RNA as well as complementary RNA is inhibited in vivo at the nonpermissive temperature (40 °), although the viral RNA polymerase could be detected by an in vitro test and was active in vitro at the nonpermissive temperature. When infected cells were incubated at the permissive temperature (33 °) for 3 hr and then shifted to 40 °, almost normal yields of viral proteins and activities including infectious particles were found.