Their previous studies demonstrated an association between proinflammatory cytokine interleukin (IL)-17A and R. anatipestifer infection. Here, they provide evidence for IL-17A involvement in R. anatipestifer infection using a mouse model. Mice pretreated with IL-17A or IL-23 prior to sub-lethal dose infection of R. anatipestifer exhibited increased bacterial burden and spleen weights compared to untreated infected mice, confirming the involvement of IL-17A in susceptibility to R. anatipestifer infection in vivo.