IFN-γ plays a critical role in the defense against bacterial infections as an indispensable bridge between innate and adaptive immunity [39], our result confirmed that the level of IFN-γ and the number of CD4+ and CD8+ T cells were significantly improved by IFA; consequently, the bacterial burden in mice lungs and bacterial dissemination from lung to other organs were effectively controlled. This evidence concerns the gene CD8A and bacterial infectious disease.