Histone modification profiles acquired by transfected KSHV bacmids and de novo infecting episomes.

<p>(<b>A</b>) SLK cells were transfected with KSHV BAC16 <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004274#ppat.1004274-Brulois1" target="_blank">[143]</a> DNA and selected with hygromycin for 24 days to select for bacmid-carrying cells. Histone modifications were analyzed by high resolution ChIP on microarray analysis with antibodies directed against H3K4me3 (upper panel) or H3K27me3 (lower panel). (<b>B</b>) SLK cells were infected with KSHV and chromatin was prepared at indicated time points, and histone modification profiles were investigated by high resolution ChIP on microarray analysis with antibodies directed against H3K4me3 (upper panel) or H3K27me3 (lower panel). Arrows above H3K4me3 profiles denote peaks that are prominent at 24 h post infection, but were diminished upon acquisition of repressive H3K27me3 marks at later time points. Normalized signal intensity values from the profiles shown in A and B as well as from previously investigated SLK cells at 5 d post infection (5 dpi) <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004274#ppat.1004274-Gunther1" target="_blank">[14]</a> were used to generate the heat maps shown in (<b>C</b>). The heat maps indicate the chromatin status as being either naïve (black), dominated by H3K4me3 (green) or H3K27me3 (red), or characterized by the presence of both modifications (yellow). The latter state is designated as ‘putative bivalent’ since co-occurrence of both modifications on the same nucleosome has formally been proven only for the ORF50/Rta promoter <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004274#ppat.1004274-Gunther1" target="_blank">[14]</a>.