Changes in mRNA expression levels of inflammatory cytokines and receptors. PCR array assay system was used to assess the mRNA expression levels of interleukins (A), chemokines (B), tumor necrosis factor (C), colony-stimulating factors (D), and receptors of chemokine (E) in PAMs incubated with PCV2 and controls after 1, 24, and 48 h. The Ct value of actin-β in PCV2-infected and control groups (F). Fold regulation was obtained by comparing the relative expression intensity of PCV2-infected and uninfected control PAMs. Results are mean ± SE of three independent experiments. * represents p < 0.05.