In vitro synthesis of messenger RNA by a defective interfering particle of vesicular stomatitis virus.

Abstract
A defective interfering [DI] particle derived from the heat-resistant strain of vesicular stomatitis virus was analyzed for the presence of virion-associated RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) activity. The RNA synthesizing capacity of the DI particles in vitro was similar to that of the wild-type virus. Characterization of the RNA produced in vitro indicated that the DI particles were able to synthesize vesicular stomatitis virus leader RNA and 4 virus mRNA species that sediment at 12-18 S. These RNA products were identical to the mRNA synthesized in vitro by the wild-type virus in regard to size, polyadenylation, capping and methylation. Unlike the wild-type virus, the purified DI particles did not synthesize the large mRNA species sedimenting at 31 S in vitro. Possible mechanisms of homotypic and heterotypic interferences shown by this DI particle are discussed.