TKT and infection: At this time after infection, the DNA in the promoters of IE (ICP0), E (TK) and L (VP16) genes co-immunoprecipitates with histones bearing silencing markers, and the efficiency of immunoprecipitation of HSV-1 chromatin is comparable to that of cellular chromatin [11, 12, 23, 32, 42, 65, 66], always constrained by the intrinsic limitations of populational analyses and infection synchronization.