RNA polymerase activity in purified infectious vaccinia virus.

Abstract

It has been shown that single-stranded RNA-containing viruses are able to initiate the synthesis of viral proteins in infected cells by using their RNA genome as a messenger for protein synthesis.1 In this situation, the first virus-induced macromolecular synthesis in an infected cell is probably the synthesis of protein molecules. However, a virus containing only double-stranded DNA presumably could not induce new viral protein synthesis in this way. Instead, a messenger RNA would have to be made from the viral DNA template. This would require that an RNA polymerase enzyme be available to the infecting virus genome before the virus could have induced any of its own proteins. On these grounds it could be predicted that the first viral-induced macromolecular synthesis in cells infected with a double-stranded DNA virus would be the synthesis of RNA and that the RNA polymerase enzyme used to catalyze this synthesis pre-existed before the initiation of infection. It has been shown in both vaccinia-infected cells2-4 and in T4-