A Genetic Approach to Studies on the Synthesis of the Complementary RNAs of Fowl Plague Virus

The rate of incorporation of 5-fluorouracil into complementary strands of replicating RNA of fowl plague virus (FPV) has been studied. The efficiency of incorporation was estimated by determination of the reversion frequency in S-mutants with known types of base transitions in the RNA of the virus particle. It was established that maximum incorporation of 5-fluorouracil into progeny virus particle RNA took place between 2 and 4 h after infection. The maximum incorporation of the mutagen into complementary RNA (plus strands) occurred when the cells were exposed to 5-fluorouracil from 1 to 2 h after infection.