CTCF and infection: Previous studies identified TFII-I as a key targeting factor for CTCF, particularly with respect to cellular metabolism genes (25), and as CTCF has been shown to repress gene expression in multiple DNA viruses, including EBV and KSHV (43), it has been proposed that TFII-I binding to the HAdV genome during infection might recruit CTCF to HAdV promoters to repress them (42).