Oxidative stress induces autophagy in PCV2-infected PK 15 cells. PK15 cells were infected with PCV2 at MOI of 1, after 2 h infection, the cells were further cultured in fresh medium with different concentrations of H2O2 for 48 h. A–C The expression of ATG5 and LC3-II protein was detected by Western blotting. D Cells were transfected with GFP-LC3 plasmid and analyzed by fluorescence microscopy for the presence of fluorescent GFP-LC3 puncta. Scale bar: 10 μm. All results are presented as mean ± SEM (n = 3, each). Significance compared with single PCV2-infected group (*P < 0.05 and **P < 0.01).