A NEW VACCINIA VIRUS INTERMEDIATE TRANSCRIPTION FACTOR

Transcription of the vaccinia virus genome is mediated by a virus-enco ded multisubunit DNA-dependent RNA polymerase in conjunction with earl y-, intermediate-, and late-stage-specific factors. Previous studies i ndicated that two virus-encoded proteins (capping enzyme and VITF-1) a nd one unidentified cellular protein (VITF-2) are required for specifi c transcription of an intermediate promoter template in vitro. We have now extensively purified an additional virus-induced intermediate tra nscription factor with a native mass of approximately 100 kDa.