Fig 1: ATR and Chk1 Are Required for Vaccinia Genome Replication(A) Immunoblot analysis demonstrates that ATR (ATRi VE-821), but not ATM (ATMi KU55633), inhibits late (F13 and A27), but not early (H5), viral protein expression 8 hr post-infection.(B) Immunofluorescence analysis of cells infected for 8 hr reveals that ATRi inhibits expression of RFP-A3, a late viral core protein. Scale bar, 10 μm.(C) ATRi inhibits viral production 8 hpi.(D) Quantification of viral genome copy number in cells infected for 6 hr in the presence of AraC or ATRi 1 hr pre- (−1) or post- (+1) infection. Both AraC and ATRi inhibit expression of F13 (late), but not H5 (early).(E) Removal of AraC 4 hr post-infection in the presence, but not absence, of ATRi reduces genome replication and late (F13, A27), but not early (H5), viral protein expression.(F) Removal of AraC 4 hr post-infection in the presence of the indicated inhibitors reduces genome replication and late gene expression.All error bars represent SEM from three independent experiments, with ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001.