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Mucosal-associated invariant T (MAIT) cells are innate T lymphocytes activated by bacteria that produce vitamin B2 metabolites. Mouse models of infection have demonstrated a role for MAIT cells in antimicrobial defense. However, proposed protective roles of MAIT cells in human infections remain unproven and clinical conditions associated with selective absence of MAIT cells have not been identified. We report that typhoidal and nontyphoidal Salmonella enterica strains activate MAIT cells. However, S. Typhimurium sequence type 313 (ST313) lineage 2 strains, which are responsible for the burden of multidrug-resistant nontyphoidal invasive disease in Africa, escape MAIT cell recognition through overexpression of ribB This bacterial gene encodes the 4-dihydroxy-2-butanone-4-phosphate synthase enzyme of the riboflavin biosynthetic pathway. The MAIT cell-specific phenotype did not extend to other innate lymphocytes. We propose that ribB overexpression is an evolved trait that facilitates evasion from immune recognition by MAIT cells and contributes to the invasive pathogenesis of S. Typhimurium ST313 lineage 2.

Original publication

DOI

10.1073/pnas.2007472117

Type

Journal article

Journal

Proc Natl Acad Sci U S A

Publication Date

25/08/2020

Volume

117

Pages

20717 - 20728

Keywords

MR1, ST313, Salmonella Typhimurium, invasive nontyphoidal Salmonella, sequence type 313, Africa South of the Sahara, Anti-Bacterial Agents, Diarrhea, Humans, Immune Evasion, Mucosal-Associated Invariant T Cells, Salmonella Infections, Salmonella typhimurium