Fig 2.

Binding of viral RdRp to vRNA templates containing wild-type or mutant 5′dA10 promoters. (A) Schematic representation of the “in cell culture” vRNA binding assay. Plasmids encoding NA vRNA templates were cotransfected with plasmids expressing TAP-tagged influenza A virus polymerase (PB1, PB2, and PA-tap). (B) Input RNA levels as analyzed by primer extension and autoradiography (top panel). Ribosomal 5S rRNA is shown as loading control (second panel). Partially purified viral polymerase was analyzed by SDS-PAGE and staining with silver (third panel). The RdRp subunits as well as the copurifying Hsp70 proteins are indicated. Levels of RNA copurified with RdRp are shown in the bottom panel.