Fig. 2.

Luciferase activities of duck RNA polI promoter in avian cells. Plasmids encoding PB2, PB1, PA, and NP proteins derived from influenza virus A/PR/8/34 were transfected into (A) CCL-141 and (B) DF-1 cells, together with luciferase reporter constructs containing different length of the duck RNA poly I promoters (nt −1 to −1000, −750 −500, and −250) and an antisense firefly luciferase coding sequence based on pUC19 vector. Data were normalized relative to the Renilla luciferase activity and represented with ±standard deviation. *** p-value < 0.0001.