As shown in Fig. 3, although there were no typical symptoms after infection, the expression of proinflammatory cytokines IL-1β, IL-6 and IL-8 were significantly induced at 5 dpi in lungs and at 7 dpi in spleen, and at the same time, the expression of anti-inflammatory cytokine IL-10 was also induced. This evidence concerns the gene IL1B and infection.