FIG. 3.

YLD virus RNA polymerase activity using a VV promoter. CV-1 cells were transfected with PSC65 expression plasmid (with the β-Gal gene regulated by the VV synthetic P7.5 promoter), followed by infection with the YLD virus. (A) Cells transfected with PSC65 clone; (B) cells infected with YLD virus alone; (C) cells both transfected and infected. Blue staining is evident after X-Gal staining only in the cells that are both infected and transfected, demonstrating the function of this promoter in YLD virus-infected cells.