(A-D) The porcine alveolar macrophages were isolated from mock-, PCV1- or PCV2-infected piglets. Then the cells were seeded into 6-well plates and cultured for 24 h, further infected by 1 MOI PRRSV or 50 MOI H. parasuis for 6 h or 24 h, or stimulated by LPS/IFN-γ (1000 ng/ml, 100 ng/ml) or LPS/R848 (1000 ng/ml, 5 μg/ml) for 6 h or 24 h. The protein and mRNA levels of IL-12p40 were measured by ELISA and q-PCR, respectively. (E-H) The PAMs from health pigs were isolated and cultured for 24 h, then the cells were infected by PCV1, PCV2, or mock for 24 h and further challenged by PRRSV or H. parasuis, or stimulated by LPS/IFN-γ or LPS/R848. The protein and mRNA levels of IL-12p40 expression were measured by ELISA and qPCR, respectively. *P < 0.05, **P < 0.01 versus Mock infected cells with same secondary infection or same stimulation. #P < 0.05, ##P < 0.01 versus PCV1 infected cells with same secondary infection or same stimulation.