Acetylation of histone H4 is reduced in BHV-1- but not in VP22 deletion mutant-infected MDBK cells. Cells were infected with BHV-1 or the VP22 deletion mutant virus (vdUL49) for 18 h and then treated with a 500 nM concentration of the deacetylase inhibitor trichostatin A for 3 h. Acid-soluble protein extracts (20 mg) from mock-infected (lane 1), BHV-1-infected, or vdUL49-infected MDBK cells were fractionated on an SDS-polyacrylamide gel and blotted with anti-acetyl H4 histone, anti-H4, or antiglycoprotein D (gD) antibodies. Note that the acetylation, but not the amount, of histone H4 was reduced in BHV-1- but not vdUL49-infected cells.