The nature of the RNA products synthesized in vitro by subviral components of vesicular stomatitis virus

Abstract

Purified VSV preparations were disrupted by the nonionic detergent Triton X-100 in the presence of either low (0.4 M NaCl) or high (0.8 M NaCl) salt conditions. A sedimentable core particle produced in the presence of low salt contained only three of the principal viral proteins and was active in the transcription of RNA. These products were identical to authentic in vitro VSV mRNA species in their size distribution, the presence of 3′-polyadenylate sequences, and the presence of methylated and blocked 5′-termini. Disruption of virions in high salt conditions produced a sedimentable core containing only one viral protein which could transcribe RNA only when mixed with the corresponding supernatant fraction of viral proteins. The RNA products produced by such reconstitution were also indistinguishable from authentic VSV mRNAs by the same criteria. Attempts to methylate exogenous VSV mRNA or synthetic “cap” structures by fractionated virion components were unsuccessful. It is concluded that during VSV transcription, the blocking, methylating, and polyadenylating activities are all transcription dependent, and can be mediated by a minimum of three viral proteins.