J. Garces et al., REACTIVATION OF TRANSCRIPTION FROM A VACCINIA VIRUS EARLY PROMOTER LATE IN INFECTION, Journal of virology, 67(9), 1993, pp. 5394-5401
We have studied the kinetics of RNA synthesis from the vaccinia virus
7,500-molecular-weight gene (7.5K gene) which is regulated by early an
d late promoters arranged in tandem. Unexpectedly, after a first burst
of RNA synthesis early in infection, transcription was reactivated la
te in infection. Reactivation was not dependent on the location of the
promoter in the genome or on the presence of the upstream late regula
tory sequences. The mRNA synthesized from the reactivated promoter in
the late phase had the same 5' and 3' ends as the molecules transcribe
d in the early phase. Interestingly, these molecules were efficiently
translated despite the absence of the poly(A) leader characteristic of
late mRNAs. Reactivation appears to be dependent on virus assembly si
nce it is prevented by rifampin, a specific inhibitor of morphogenesis
. Finally, analysis of various other early genes showed that reactivat
ion is not unique to the 7.5K early promoter.