Epstein-Barr Virus Interferes with the Amplification of IFNα Secretion by Activating Suppressor of Cytokine Signaling 3 in Primary Human Monocytes
Figure 6
Activation of SOCS3 by the viral protein Zta.
(A) Monocytes (5×106) were mock- or EBV-stimulated for 20 hours and expression of the EBV protein Zta was evaluated by Western blot analysis. (B) HEK293 cells were transiently co-transfected with a vector encoding WT Zta or mutated Zta (ΔZta) at indicated concentrations along with a SOCS3 promoter-driven luciferase reporter vector. Luciferase assay was performed 48 hours post-transfection. (C) Monocytes (5×106) were transfected with 300 ng of either Zta vector or ΔZta vector or mock vector control (CTRL). Forty-eight hours following transfection, monocytes were stimulated with IFNα (1000 U/ml) for 15 minutes. The expression of SOCS3 and phospho(p)STAT2 proteins was evaluated by Western blot analysis. Membranes were also probed with anti-Actin as a loading control. Densitometry was performed and represents fold protein induction (relative to mock-transfected cells) ± std. dev. of experiments performed in duplicate. Data are representative of two independent experiments. *p≤0.05 compared to non-transfected control cells. NS: non-stimulated; NT: non-transfected.