Human cytomegalovirus UL23 inhibits transcription of interferon-γ stimulated genes and blocks antiviral interferon-γ responses by interacting with human N-myc interactor protein
U251, U251-C, and U251-UL23 cells were treated with anti-Nmi siRNA and control siRNA, following the procedures described previously . At 24 hours treatment, cells were transfected with reporter plasmid pGL3-Promoter-3×GAS and the internal control reporter pRL-TK. After 24 hours, cells were cultured in the absence (-IFN-γ) and presence (+IFN-γ) of IFN-γ (1000 U/ml) for 24 hours. The levels of UL23 and Nmi were determined by western blot analysis using those of actin as the loading control. Luciferase activity was determined luminometrically as relative light units (RLU). The values of the relative luciferase level represent the ratios of the levels of luciferase in different cells to those in parental U251 cells in the absence of IFN-γ. The experiments were repeated three times. The standard deviation is indicated by the error bar.