FIG. 8.

Ni N protein, but not Ni-CE N protein, functions to evade activation of RIG-I-mediated antiviral response. (A) SYM-I cells were cotransfected with pRL-TK, 4×IRF-3-Luc, and 1 μg of pEF-Flag-RIG-I or empty vector. At 24 h posttransfection, the cells were infected with Ni, Ni-CE, and CE(NiN) strains at an MOI of 2 and incubated for 24 h. Then, the cells were lysed and luciferase activities were measured. *, Significant difference (P < 0.01); ns, no significant difference. (B) SYM-I cells were inoculated, in suspension, with each virus strain at an MOI of 2 FFU/cells and seeded. After 24 h, cells were transfected with pRL-TK, 4×IRF-3-Luc, and 1 μg of pEF-Flag-RIG-IC. After 24 h, the cells were lysed and luciferase activities were measured. *, Significant difference (P < 0.01); ns, no significant difference. (C) SYM-I cells were inoculated, in suspension, with each virus strain at an MOI of 2 FFU/cells and seeded. After 24 h, cells were transfected with pRL-TK, 4×IRF-3-Luc, and 0.5, 1, or 2 μg of pEF-Flag-RIG-IC. After 24 h, the cells were lysed, and the luciferase activities were measured. *, Significant difference versus mock-transfected cells (P < 0.01). (D) SYM-I cells were inoculated, in suspension, with each virus strain at an MOI of 2 FFU/cells and seeded. After 24 h, cells were transfected with pRL-TK, 4×IRF-3-Luc, and 1 μg of pEF-Flag-RIG-IN. After 24 h, the cells were lysed, and the luciferase activities were measured. The data are presented as means (± the SD) of three independent replicates. ns, No significant difference.