Synthesis of Virus DNA and Polypeptides by Temperature-sensitive Mutants of Rabbitpox Virus

Abstract

Eighteen temperature-sensitive (ts) mutants of rabbitpox virus were examined for defects in synthesis of DNA and protein. Two mutants (ts-3 and ts-16) were defective in DNA synthesis (DNA-), since both incorporated significantly less than wild-type amounts of labeled thymidine into acid-precipitable material when infected [pig kidney PK-15] cells were incubated at the restrictive temperature. Both these mutants gave only the early class of virus polypeptides when infected cell extracts were examined by SDS[sodium dodecyl sulfate]-polyacrylamide slab gel electrophoresis following incubation at 40.degree. C. Nine of the remaining 16 DNA+ ts mutants (ts-1, ts-2, ts-6, ts-12, ts-15, ts-17, ts-31, ts-32 and ts-33) synthesized wild-type levels of most virus polypeptides at 40.degree. C; 6 DNA+ ts mutant (ts-14) ts-7, ts-8, ts-9, ts-11, ts-23 and ts-24) were defective in the post-transitional cleavage of the polypeptides involved in membrane stabilization and particle assembly; 1 DNA+ (ts-14) synthesized only the early class of virus polypeptides, implying that either replicated DNA was not fully functional or that a specific early function was required for late transcription.