Various studies suggest that IFN-γ production by CTLs is required for the clearance of intracellular bacterial infections such as M. tuberculosis [68], C. trachomatis [69], L. monocytogenes [70], Brucella [67], T. gondii [157], F. tularensis [158], and Rickettsia [66]. The gene discussed is IFNG; the disease is bacterial infectious disease.