FIG. 6.

Effects of transient expression of Ni or Ni-CE N protein on IRF-3-dependent promoter activities in SYM-I cells infected with NDV or Ni-CE strain. SYM-I cells were cotransfected with pRL-TK, 4×IRF-3-Luc, and 1 μg of each plasmid driving the expression of the indicated viral protein or empty vector. At 24 h posttransfection, the cells were infected with NDV at an MOI of 1 and incubated for 12 h (A) or infected with Ni-CE strain at an MOI of 2 and incubated for 24 h (B). Then, the cells were lysed, and the luciferase activities were measured. The data represent firefly luciferase activity normalized to Renilla luciferase activity and are presented as means (± the SD) of three independent replicates. *, Significant difference (P < 0.01); ns, no significant difference.