S. Typhimurium infection of humanized mice resulted in elevated levels of the human TH1 cytokines IL-12 (Fig. 6F) and IFNγ (Fig. 6G), whereas infection with ssrB mutant S. Typhimurium or S. Typhi elicited lower cytokine expression, with significantly lower levels of IL-12. The gene discussed is IFNG; the disease is infection.