Fig. 5

Autophagy is involved in H9N2 influenza virus replication by regulating the oxidative stress via Akt–TSC2–mTOR signaling pathway. A549 cells were pre-treated with IGF-1, followed by infection with H9N2 influenza virus. (a) Cells were collected and the protein expression levels of phospho-Akt, Akt, phospho-TSC2, TSC2, phospho-mTOR, mTOR, phospho-pS6, S6 and LC3-II were detected by western blot analysis. Following transfection with control siRNA or TSC2 siRNA, A549 cells were infected with the H9N2 influenza virus. (b, c) Protein expression levels of TSC2 and LC3-II were detected by western blot analysis. (dd) Supernatants from A549 cells were collected, and the viral titer was determined by measuring TCID₅₀. (e) ROS generation, (f) MDA contents, and (g) SOD1 activity were measured in cells. The data are presented as the means ± SD (n = 5). **P < 0.01 relative to control, ^##P < 0.01 relative to H9N2