Frog virus 3 requires RNA polymerase II for its replication.

The involvement of host cell RNA polymerase II in the replication of frog virus 3 (FV 3) was examined in alpha-amanitin-sensitive or -resistant Chinese hamster ovary (CHO) cells in the presence and absence of alpha-amanitin. In the presence of alpha-amanitin, FV 3 replicated normally in resistant CHO cells but failed to do so in sensitive CHO cells. Synthesis of virus-specific RNAs and proteins was inhibited in sensitive cells infected in the presence of alpha-amanitin, but in alpha-amanitin-resistant cells, as expected, virus-specific protein synthesis and, by implication, virus-specific RNA synthesis were not affected by the presence of the drug. Inhibition of FV 3 replication was maximum when alpha-amanitin was added to sensitive CHO cells before virus adsorption, but the drug had no effect on virus replication if added after the adsorption. These data indicate that host RNA polymerase II was required for early transcription of the FV 3 genome and confirm a nuclear requirement for FV 3 RNA synthesis (R. Goorha et al., Virology 82:34-52, 1978).