Polyamines stimulate DNA-dependent RNA synthesis catalyzed by vaccinia virus.

The RNA synthesis in purified vaccinia virus can occur in the presence of either Mg2+ or Mn2+ if polyamine (spermidine or spermine) is present in the assay system. Under our assay conditions transcription was linear up to 30 min and the RNAs synthesized had a sedimentation coefficient of about 8 to 12 S. We also prepared a virus extract from purified vaccinia virus and tested for in vitro transcription. The soluble transcription system was dependent on the addition of exogenous DNA and single-stranded DNA was a more effective template than double-stranded. In the presence of polyamine and Mg2+ or Mn2+ the viral RNA polymerase was active in the transcription of total native vaccinia DNA and a small fragment cloned in pBR322.