In our study, the infection of pAMs with PRRSV significantly increased the expression of IFN-β and IFN-γ, which is in agreement with previous studies showing augmented IFN-α and IFN-γ levels in the cell line 3D4/21 (alveolar macrophages of porcine origin), after the challenge with PRRSV [28]. This evidence concerns the gene IFNB1 and infection.