Transgenic expression of NS1 rescues the ability of an NS1 deletion virus to form dsRNA replication complexes. BHK21-VEEV-NS1 cells were transfected with CMV-launched infectious cDNA clones of pKUN1-WT, pKUN1-NS5 GDD/GAA, or pKUN1-∆-NS1. 48 hours later, cells were co-stained with antibodies against dsRNA (left panels) or NS3 (middle panels). Nuclei were stained blue with DAPI and images were merged (right panels). Images were processed by confocal microscopy. Representative images from three independent experiments are shown.