FIG 7.

Type I IFN treatment inhibits MCPyV early transcription. (A) Treatment with IFN-β, but not IFN-λ1, inhibits MCPyV activities. MCPyV-infected HDFs were either untreated or treated with 1,000 U/mL IFN-β, 1,000 U/mL IFN-λ1, or both for 30 min before FBS was added to the medium on day 2 postinfection. Cells were fixed on day 5 postinfection, immunostained for VP1 and LT, and counterstained with DAPI. Bars, 100 μm. (B) HDFs stably expressing an MCPyV early promoter-driven luciferase reporter were either untreated or treated with 500 U/mL type I IFN for 20 h. Cell lysates were harvested for luciferase assays and normalized to the protein levels measured by Bradford assays. (C) HDFs stably expressing MCPyV early promoter-driven LTT/ST were untreated or treated with 1,000 U/mL IFN-α, IFN-β, or IFN-λ1 for 19 h. LTT mRNA levels were measured by RT-qPCR and normalized to GAPDH mRNA levels. The value for one of the no-treatment groups was set as 1. Error bars represent the standard deviations from three independent experiments. ***, P < 0.001; ns, not significant.