FIG 3.

SUMO confers resistance to VSV in an IFN-independent way. (A) HeLa-wt, HeLa-SUMO1, and HeLa-SUMO3 cells were infected with VSV at an MOI of 1 for 4 h or 8 h. Total RNA was extracted, and mRNA encoding IFN-α, IFN-β, IFN-λ1, IFN-λ2/λ3, IFN-γ, and RPL13A was quantified by qRT-PCR. Mean values and standard deviations from three independent experiments are shown. (B) HeLa-wt cells were left untreated or treated for 24 h with 100 units/ml of IFN-β in the absence or the presence of 20 μg/ml of purified anti-IFNAR1 antibody (Ab) before infection with VSV at an MOI of 1 for 8 h. (C) HeLa-wt, HeLa-SUMO1 (HeLa-S1), and HeLa-SUMO3 (HeLa-S3) cells were infected with VSV at an MOI of 1 for 8 h in the absence or the presence of 20 μg/ml of anti-IFNAR1 antibody. (D) STAT1 depletion does not alter the anti-VSV effect of SUMO. HeLa-wt, HeLa-SUMO1, and HeLa-SUMO3 cells were untreated (control [Ctrl]) or transfected with scrambled siRNA (Sc) or STAT1-specific siRNA (STAT1). Two days later, the cells were infected with VSV at an MOI of 1 for 8 h. Cell extracts were analyzed by Western blotting and revealed by antibodies directed against STAT1, VSV proteins, and actin.