FIG. 2.

IFN-β induction in A549 cells by heterologous RIG-I and MDA5 stimuli is not affected by expression of the HPIV1 C proteins in trans. (A) A549 cells were preinfected with WT HPIV1 at an MOI of 5 for 24 h and then superinfected with either P(C−) HPIV1 or GFP-expressing ΔNS1/NS2 RSV at a MOI of 5 for another 24 h. IFN-β expression was measured by real-time PCR and was normalized to the mock-preinfected, mock-superinfected sample. *, P < 0.01 compared to mock-preinfected samples. (B) C protein expression was induced in stable C protein-expressing 293 cells with 1 μg/ml doxycycline for 24 h. Cells were then mock infected or infected with P(C−) HPIV1 at an MOI of 5 for another 24 h. IFN-β expression was measured by real-time PCR and was normalized to the control treated, mock-infected sample. *, P < 0.01 compared to control treated cells. (C) C protein expression was induced in stable C protein-expressing 293 cells with 1 μg/ml doxycycline for 24 h, transfected with 2.5 μg MDA5 expression plasmid for another 18 h, and then transfected with 10 μg poly(I:C) for 6 h. IFN-β expression was measured by real-time PCR and was normalized to the control treated, control transfected sample.