Induction of the viral BZLF1 gene has previously been shown to be one of th
e first steps in the reactivation of Epstein-Barr virus (EBV). Using an EBV
oriP episomal vector system, we have reconstituted the regulation of the p
romoter for BZLF1 on stably transfected episomes, mapped promoter elements
required for that regulation, and investigated mechanisms that may control
the switch between latency and the lytic cycle. Changes in histone acetylat
ion at the promoter for the BZLF1 gene appear to be a key part of the react
ivation mechanism of this herpesvirus.