Transmissible Gastroenteritis Virus Papain-Like Protease 1 Antagonizes Production of Interferon-β through Its Deubiquitinase Activity

Figure 1

TGEV PL1 inhibits SeV-induced expression of IFN-β-Luc in a dose-dependent manner. (a) HEK-293T cells grown in 24-well plates were transfected with 1 μg plasmid encoding Myc-TGEV PL1 or empty vector and infected with SeV 24 h later (100 hemagglutinating activity units/well). After 10 h infection, cells were lysed, and activities of IFN-β-Luc and pRL-TK reporters were determined according to the manufacturer’s protocol. Myc-TGEV PL1 inhibits the activities of IRF3 (b), NF-κB (c), and AP-1 (d). Luciferase activities were assayed as described for (a). Results represent the means and standard deviations of data from three independent experiments. (e) PK-15 cells grown in 12-well plates were transfected with 500 ng plasmid Flag-PL1 and empty vector and infected with SeV 24 h later. After 10 h infection, cell supernatants were collected and analyzed for IFN-β production by ELISA. (f) HEK-293T cells grown in 6-well plates were transfected with 2 μg plasmid encoding Myc-TGEV PL1 or empty vector and infected with SeV 24 h later (100 hemagglutinating activity units/well). After 10 h infection, cells were lysated and detected by Western blot. (g) Immunofluorescence microscopy of HeLa cells expressing Flag-PL1 and IRF3-GFP. Cells were fixed 24 h after transfection and 10 h SeV infection, and Flag-tagged products were visualized using confocal microscopy. Asterisks indicate statistical significance ().

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