FIG 3.

NDV V protein suppresses MAVS-mediated IFN-β signaling transduction. (A) Schematic diagram of RIG-I/MDA5-mediated IFN-β signaling pathway. (B and C) HEK-293T cells were cotransfected with PRL-TK, expression plasmid RIG-I N, MDA5 N, MAVS, TBK1, IKKε, or IRF3-5D or empty plasmid (vector), and either empty vector (−) or Flag-V (1 or 2 μg/ml; wedge) as well as p-125Luc (B) or pISRE-luc (C). At 24 hpt, cells were harvested and assessed for luciferase activity. The results are presented as relative luciferase activity. Expression levels of expressed proteins were analyzed by immunoblot analysis of the lysates with anti-Flag or anti-β-actin antibody. (D) Schematic diagram of TLR3-mediated signaling pathway. (E and F) HEK-293T cells were cotransfected with PRL-TK, TRIF, and either empty vector or Flag-V (1 or 2 μg/ml; wedge) as well as p-125Luc (E) or pISRE-luc (F). At 24 hpt, cells were harvested and assessed for luciferase activity. The results are presented as relative luciferase activity. Expression levels of expressed proteins were analyzed by immunoblot analysis of the lysates with anti-Flag or anti-β-actin antibody. Data are presented as means from three independent experiments. **, P < 0.01; ***, P < 0.001.