Initiation and direction of RNA transcription by vesicular stomatitis virus virion transcriptase

The initiation of RNA transcription by the virion-bound RNA transcriptase of vesicular stomatitis virus has been examined. Multiple initiation sequences have been observed, two of which have been characterized (pppApCpGp... and pppGpCp...) suggestive of a transcription process which can start at different sites along the template RNA. By the use of sequential labeling techniques and exonucleases, it has been determined that there is a 5' to 3' direction of product RNA synthesis.