Reports have indicated that in zebrafish, the expression of immune genes were altered in response to the infection of a live attenuated E. tarda strain (Yang et al., 2012), and that the mRNA levels of inflammatory cytokines (interleukin-1β and tumor necrosis factor-α) were significantly upregulated in E. tarda-infected fish (Pressley et al., 2005). This evidence concerns the gene TNF and infection.