FIG 5 .

DNA repair factors are preferentially recruited to viral genomes. Chromatin immunoprecipitation analysis was performed on undifferentiated and differentiated HPV-positive cells. (A) ɣ-H2AX, (B) RAD51, and (C) BRCA1 bind at higher levels to the URR of HPV 31 than to the human Alu repeat, and the difference increases upon calcium-induced differentiation. Data are represented as percent input or normalized to the URR as fold enrichment over URR per differentiation condition. For fold enrichment measurements, a value of less than one indicates less binding to Alu than the URR. Similar results were observed in at least three independent experiments. Statistical significance is indicated on the graph and was analyzed using a Student’s t test. ****, P < 0.0001; *, P < 0.05; ns, not significant. Statistical significance data indicate results of comparisons between Alu occupancy and URR occupancy for either undifferentiated or differentiated HPV-positive cells. All primer efficiencies were determined to be comparable. IgG background signal data are shown in the supplement material.