Autophagy inhibition increases apoptosis in PCV2-infected PK15 cells. PK15 cells were infected with PCV2 at MOI of 1, cells were pretreated with 3-MA or transfected with the siATG5 and then cultured in the presence of H2O2 for 48 h. A, B The expression of cleaved caspase-3 protein was detected by Western blotting. C–F The mRNA levels of caspase-3, caspase-8, Bax and Bcl-2 was measured by RT-PCR. G, H Morphology of apoptotic cell nuclei was detected by staining Hoechst 33258. The data represent the mean ± SEM (n = 3, each). Significance compared with PCV2-infected and H2O2 treatment group (*P < 0.05 and **P < 0.01).