[Production of temperature-sensitive mutants of vaccinia virus with the aid of nitrosomethylurea, and their preliminary characteristics].

The possibility of using nitrosomethylurea for production of one-hit temperature-sensitive (ts) mutants of vaccinia virus suitable for genetic and biochemical studies was explored. The effect of nitrosomethylurea on replicating DNA of the virus produced 26 ts mutants, the effectiveness of mutagenesis being 10%. In recombination experiments with 12 of them it was shown that all the mutants under study had single ts defects of the genome. All ts mutants were capable of synthesizing DNA under nonpermissive conditions; 16 ts mutants had thermolabile virions.