FIG 7.

HSV-1 strain KOS has increased H3K27me3 marks compared to those of strain 17syn⁺ during latency and PI3K inhibitor-induced reactivation in LUHMES. Chromatin immunoprecipitation was performed to measure heterochromatin formation on HSV-1 genomes from cultures of LUHMES cells infected with 17syn⁺ or KOS(M) at 8 days postinfection (latency) or following Ly294002-induced reactivation from latency. Shown are three regions of the HSV-1 genome queried by qPCR following ChIP. (A to C) ICP4 (A), the LAT promoter (B), and the late gene, gC (C). Heterochromatin was assessed by immunoprecipitation with an antibody recognizing H3K27me3. ChIP-qPCR data were normalized to percent input over total H3. Reactivation was induced at day 8 postinfection with 10 μM Ly294002, and reactivation samples were harvested at the indicated times. These data point to a significant reason why KOS(M) fails to reactivate. As shown here, 17syn⁺ genomes are associated with fewer heterochromatin marks than KOS(M), indicating less accessibility of the KOS genome for replication and transcriptional activities. For each time point, significance was determined by ordinary two-way ANOVA with Sidak’s multiple-comparison test across 3 biological replicates (*, P < 0.05; **, P < 0.001; ***, P < 0.0001) (n = 3).