Fig. 8. Changes in mRNA expression levels of various Toll-like receptors (TLRs) after porcine circovirus type 2 (PCV2) infection. Real-time RT-PCR was used to assess the mRNA expression levels of TLR-2, -3, -4, -7, -8, and -9 in porcine alveolar macrophages incubated with PCV2 and controls after 6, 12, 24, and 48 h; ^*p 0.05, ^**p < 0.01.