TNF and infection: At 2-day post-infection, gene expression for IFN-γ was significantly increased in PC group compared to NC and EXP groups (P < 0.05), but no significant difference was found between NC and EXP groups (P > 0.05); in addition, no significant differences were observed in the IL-1β and TNF-α productions among EXP, PC, and NC groups (P > 0.05); the expression of IL-8 was significantly mounted in the PC group compared to EXP group (P < 0.05), but no significant difference was observed between EXP and NC groups (P > 0.05), and the same change was found between PC and NC groups (P > 0.05).