Among the five flagellins, flaB was the most capable of inducing TLR5-meditated inflammatory responses, hence we knocked out the flaB gene in V. anguillarum and tested the infection ability of the mutant to explore the function and mechanism of flaB. A time course of TLR5 expression was performed by real-time PCR in FICEs after treatment with the flaB mutant. This evidence concerns the gene TLR5 and infection.