FIG 3 .

S. Typhimurium bacteria lacking DalS are more susceptible to neutrophil DAO killing in vivo. (A) Western blot of DAO in liver, spleen, and cecum from uninfected mice or mice infected with S. Typhimurium (S.tm). The positions of molecular weight markers (in kilodaltons) are shown to the left of the blots. The relative density of the DAO signal adjusted to the GAPDH signal is shown below the Western blot. (B) Neutropenic mice fail to accumulate splenic DAO following S. Typhimurium infection. Neutropenic mice were infected with S. Typhimurium, and organs were probed for DAO (2× spleen vol., twice the amount of sample loaded). (C) Neutropenia normalizes the fitness defect of the S. Typhimurium ΔdalS mutant. Control mice and neutropenic mice were infected with an equal mixture of wild-type S. Typhimurium and S. Typhimurium ΔdalS mutant for 2 days. The competitive index data from two experiments are shown. Each symbol represents the value for an individual mouse. The mean value for the group of mice is shown by the short horizontal black line. The broken line shows a competitive index of 1. (D) Inhibition of DAO in vivo restores virulence to ΔdalS mutants. Mice were infected with an equal mixture of wild-type S. Typhimurium and S. Typhimurium ΔdalS (first set) or an equal mixture of wild-type S. Typhimurium and S. Typhimurium ΔSPI-2 (second set) and treated with either carboxymethyl cellulose as a control or the DAO inhibitor CBIO. The competitive index data from two experiments are shown. (E) CBIO restores dalS mutant defect in singly infected mice. Mice were infected with either wild-type (wt) S. Typhimurium or S. Typhimurium dalS mutant and treated with CBIO or CMC control for 24 h. The number of CFU was normalized to spleen mass. Values that are statistically significantly different by the Mann-Whitney test are indicated by bars and asterisks as follows: *, P < 0.05; **, P < 0.01; ***, P < 0.001. Values that are not statistically significantly different (ns) are indicated.