The Vi capsular polysaccharide enables Salmonella enterica serovar typhi to evade microbe-guided neutrophil chemotaxis.

The Vi capsular polysaccharide enables Salmonella enterica serovar typhi to evade microbe-guided neutrophil chemotaxis.

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Salmonella enterica serovar Typhi (S.Typhi) causes typhoid fever, a disseminated infection, while the Nets closely related pathogen S.enterica serovar Typhimurium (S.Typhimurium) is associated with a localized gastroenteritis in humans.Here we investigated whether both pathogens differ in the chemotactic response they induce in neutrophils using a single-cell experimental approach.

Surprisingly, neutrophils extended chemotactic pseudopodia toward Escherichia coli and S.Typhimurium, but not toward S.Typhi.Bacterial-guided chemotaxis was dependent on the presence of complement component 5a (C5a) and C5a receptor (C5aR).Deletion of S.

Typhi capsule biosynthesis genes markedly enhanced the chemotactic response Hockey Protective - Shin Pads - Intermediate of neutrophils in vitro.Furthermore, deletion of capsule biosynthesis genes heightened the association of S.Typhi with neutrophils in vivo through a C5aR-dependent mechanism.Collectively, these data suggest that expression of the virulence-associated (Vi) capsular polysaccharide of S.Typhi obstructs bacterial-guided neutrophil chemotaxis.