The importance of T-cells and T-cell cytokines in innate
immunity to S. aureus has been the object of investigation [14e17].
The CD4þ T-cells not B-cells were the critical effector cells conferring
enhanced survival following S. aureus challenge in the BALB/c
murine sepsis model immunized with IsdB [13]. These events
support the potential of the IsdB as a target antigen for S. aureus
vaccine development, and promote us to investigate the protective
mechanism of CD4þ T-cell-mediated immunity. CD4þ T-cells are
primed by T-cell epitope peptides to differentiate into Th1 and Th17
type cells, both of which play central roles in protecting the host
against S. aureus infections [17]. However, little is known about the
specific IsdB CD4þ T-cell epitopes and its mechanisms involved in
the antigen-specific protective immunity.