A working model for DNA demethylation and histone acetylation regulation of MHV-68.

<p>(A) In S11E cells or latent infection <i>in vivo</i>, the RTA promoter is methylated and HDAC3 complex is recruited to the RTA promoter to suppress transcription. (B) When treated with TSA, the HDAC3 complex is rapidly removed, the RTA promoter demethylated through a passive mechanism, and RTA transcription is turned on. (C) However, when treated with 5-AzaC, though the RTA promoter becomes demethylated, HDAC3 stays at the promoter and the RTA promoter remains suppressed. M: methylation; A: acetylation.