In vitro studies on the nucleocapsid-associated RNA polymerase of wheat rosette stunt virus

RNA-dependent RNA polymerase activity was detected in both virion and nucleocapsid preparations of wheat rosette stunt virus, a plant rhabdovirus. The presence of nonionic detergent such as Nonidet P40 was essential for activity in reaction mixtures containing virions. The polymerase product was proved to be single-stranded RNA. By two-step controlled dissociation of the nucleocapsids, four subviral fractions (L protein, NS-N-RNA complex, NS protein, and N-RNA complex) were prepared. None of these fractions showed RNA polymerase activity when assayed individually. In experiments combining the various fractions, RNA synthesis was observed only when the L and NS proteins and the N-RNA complex were present in reaction mixtures.