IL-17A plays an important role in protection induced by vaccination with fibronectin-binding domain of fibronectin-binding protein A against Staphylococcus aureus infection.

Fibronectin-binding protein A (FnBPA) of Staphylococcus aureus is a microbial surface component recognizing adhesive matrix molecules and has been known as one of the most important virulence factors involved in the initiation step of S. aureus infection. Therefore, it has been considered as a potential vaccine candidate. Previous studies have reported that vaccination with FnBPA protects animals against S. aureus infection. In this study, we demonstrated that vaccination with fibronectin-binding domain of FnBPA (FnBPA541-870) protects wild-type mice but not interleukin-17A (IL-17A)-deficient mice against S. aureus infection. Moderate levels of antigen-specific immunoglobulins were produced in the sera of vaccinated wild-type and IL-17A-deficient mice. The spleen cells of vaccinated mice produced IL-17A by stimulation with the antigen, and IL-17A mRNA expression was increased in the spleens and livers of vaccinated mice after infection. CXCL1 and CXCL2 mRNA expression was increased in the spleens, and myeloperoxidase (MPO) activity in the spleens and livers was increased in the vaccinated mice after infection. These results suggest that vaccination with FnBPA541-870 induces the IL-17A-producing cells and that IL-17A-mediated cellular immunity is involved in the protective effect on S. aureus infection.