Furthermore, cxcr1, cxcr3-2, ccr3, and ccr5 mRNAs were notably up-regulated at 6 h or 12 h and maintained until 120 h post-infection, whereas cxcr3-1, cxcr4, ccr4, ccr7, and ccr9 mRNAs were notably down-regulated after E. ictaluri infection, therefore it is necessary to further verify the bioactivity of these chemokine receptors of yellow catfish in the following study. Here, CXCR4 is linked to infection.