FIG 7.

metJ deletion suppresses S. Typhimurium virulence in vivo independently of SPI-1. (A) metJ deletion reduced bacterial fitness in models of oral infection. C57BL/6J mice were infected with 10⁶ total S. Typhimurium bacteria from a 1:1 mixture of wild-type and ΔmetJ bacteria by oral gavage. Spleens were harvested at 5 days postinfection, and bacteria were quantified to calculate the competitive (Comp.) index. (B) metJ deletion reduces bacterial fitness independently of SPI-1. C57BL/6J mice were infected with 10⁹ total S. Typhimurium bacteria from a 1:1 mixture of bacteria by oral gavage. Spleens and ileums were harvested at 3 days postinfection, and bacteria were quantified to calculate the competitive index. Open squares represent mice in which no ΔhilD ΔmetJ bacteria were recovered. In these cases, the competitive index was set to be the maximum possible value by performing the calculation with one hypothetical ΔhilD ΔmetJ colony. (C) metJ reduces bacterial fitness in intraperitoneal (i.p.) models of infection. C57BL/6J mice were infected with 10³ total S. Typhimurium bacteria from a 1:1 mixture of wild-type and ΔmetJ bacteria by intraperitoneal injection. Spleens were harvested at 3 to 5 days postinfection, and bacteria were quantified to calculate the competitive index. The competitive index from each mouse is graphed as (number of ΔmetJ mutant CFU/number of WT CFU)/(number of ΔmetJ mutant CFU in the inoculum/number of WT CFU in the inoculum) or (number of ΔhilD ΔmetJ mutant CFU/number of ΔhilD mutant CFU)/(number of ΔhilD ΔmetJ mutant CFU in the inoculum/number of ΔhilD mutant CFU in the inoculum). P values, indicated at the top, were calculated by log transforming these ratios and comparing the value to an expected value of 0 using a one-sample t test. Data are from at least two independent experiments and are graphed using the geometric mean and 95% confidence interval.