Ribonucleic acid polymerase in virions of Newcastle disease virus: comparison with the vesicular stomatitis virus polymerase.

The virions of Newcastle disease virus (NDV) contained an enzyme that catalyzed the incorporation of ribonucleotides into ribonucleic acid (RNA). Optimal conditions for this polymerase activity were identical to the conditions for the vesicular stomatitis virus (VSV) polymerase, and both enzymes were active for longer times at 32 C than at 37 C. However, the specific activity of the NDV polymerase was less than 3% that of the VSV polymerase. Product RNA species from the NDV and VSV polymerase reactions annealed specifically to the homologous virion RNA species. Transcriptive intermediates containing product RNA attached to the respective virion RNA could be identified in both systems.