Cleaved MAVS, TRIF, and TANK lose their functions to trigger type I IFN production. (A) Luciferase activity assay of 293T cells transfected with wild-type and Q148A mutant MAVS plus empty vector, HA-3Cwt, or HA-3Cdm. (B) IFN-β expression as determined by qRT-PCR from 293T cells transfected with wild-type and Q148A mutant MAVS plus empty vector, HA-3Cwt, or HA-3Cdm. (C and D) The effects of cleavage fragments of MAVS by SVV 3Cpro on MAVS-mediated IFN-β production were assessed by IFN-β reporter assay (C) and qRT-PCR assay (D). (E) Luciferase activity assay of 293T cells transfected with wild-type and Q159A mutant TRIF plus empty vector, HA-3Cwt, or HA-3Cdm. (F) IFN-β expression as determined by qRT-PCR of 293T cells transfected with wild-type and Q159A mutant TRIF plus empty vector, HA-3Cwt, or HA-3Cdm. (G and H) The effects of cleavage fragments of TRIF by SVV 3Cpro on TRIF-mediated IFN-β production were assessed by IFN-β reporter assay (G) and qRT-PCR assay (H). (I) Luciferase activity assay of 293T cells transfected with wild-type and E272A-Q291A mutant TANK plus empty vector, HA-3Cwt, or HA-3Cdm. (J) IFN-β expression as determined by qRT-PCR of 293T cells transfected with wild-type and E272A-Q291A mutant TANK plus empty vector, HA-3Cwt, or HA-3Cdm. (K and L) The effects of cleavage fragments of TANK by SVV 3Cpro on TANK-mediated IFN-β production were assessed by IFN-β reporter assay (K) and qRT-PCR assay (L). Data are shown as means ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.001. Data are representative of those from at least three independent experiments.