Human epithelial A549 cells, untreated or treated with Dot1L inhibitor (48 h) (Fig. 8A,C), or transduced with lentiviruses expressing the Dot1L silencers or control shRNA (5 days) (Fig. 8B,D), were infected at low m.o.i. with RSV (1PFU/ml) (Fig. 8A,B) or VSV (10−3 PFU/ml) (Fig. 8C,D); at various times post-infection, cell supernatants were obtained for viral titration (see Methods). Here, DOT1L is linked to infection.