{
  "abstract": "Invasive non-typhoidal Salmonella (iNTS) sequence type 313 (ST313) isolates have emerged in sub-Saharan Africa, with a high incidence of multidrug resistance, enhanced intracellular persistence, increased dissemination and immune evasion. ST313 isolate D23580 was shown to avoid activation of mucosal-associated invariant T (MAIT) cells compared with a genetically similar, non-invasive Salmonella Typhimurium (S.Tm) 4/74 strain, but the mechanism remains unclear. Here, we studied immune responses to infection with typhoidal strains and ST313 isolates using comparative transcriptomic profiling of human peripheral blood mononuclear cells (PBMCs). MAIT cells responded to typhoidal strains but not to D23580. To uncover underlying mechanisms, we engineered an inducible CRISPRi system targeting riboflavin biosynthesis enzymes (rib), which process MAIT ligands, in D23580 and 4/74 strains. Several rib hypomorphs exhibited prolonged lag time in minimal media, which was more pronounced in D23580 than in 4/74. In PBMC infection, knockdown of lumazine synthase (RibH) and riboflavin synthase (RibE) resulted in contrasting MAIT cell activation phenotypes. RibH knockdown restored MAIT cell activation in D23580 but did not affect activation in 4/74. Conversely, RibE knockdown diminished MAIT cell activation by 4/74 but had no impact on MAIT cell activation by D23580. Metabolomic analysis revealed accumulation of the biosynthetic intermediate DMRL in RibE knockdown and a differential impact on riboflavin biosynthesis end products between D23580 and 4/74 RibH knockdown, suggesting altered pathway flux between the strains. Our results indicate RibH and RibE as pivotal nodes for strain-specific MAIT-activation during Salmonella infection of human PBMCs, illustrating teir central role in the complex interplay between bacterial metabolism and host immunity. Author summary: Invasive non-typhoidal Salmonella (iNTS) is a major cause of bloodstream infections in sub-Saharan Africa, where it causes severe disease and high mortality. A particular lineage, sequence type 313 (ST313), has evolved the ability to evade immune responses, including activation of mucosal-associated invariant T (MAIT) cells, an important component of the early antibacterial immune response. MAIT cells recognize small molecules generated during bacterial riboflavin (vitamin B2) biosynthesis, but how ST313 avoids this recognition has remained unclear. Here, we compared immune responses to invasive and non-invasive Salmonella strains and used an inducible CRISPR interference system to selectively reduce expression of riboflavin biosynthesis genes. We found that two enzymes, RibH and RibE, have distinct and strain-specific effects on MAIT cell activation. Reducing RibH expression restored MAIT cell activation in the invasive ST313 strain, whereas reducing RibE impaired MAIT cell activation in the non-invasive strain. Metabolomic analyses showed that these genetic perturbations altered riboflavin pathway intermediates differently in each strain, revealing unexpected differences in metabolic flux. Our findings demonstrate that changes in bacterial vitamin B2 metabolism can profoundly influence immune recognition, providing new insight into how invasive Salmonella adapts to evade host immunity.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel",
    "Division of Pulmonary, Allergy, and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon, United States of America",
    "Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America",
    "Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany",
    "Faculty of Medicine, University of Würzburg, Würzburg, Germany",
    "Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom",
    "VA Portland Health Care System, Portland, Oregon, United States of America"
  ],
  "article_type": "Research Article",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Leia Vainman"
    },
    {
      "affs": [
        1
      ],
      "name": "Corinna A. Kulicke"
    },
    {
      "affs": [
        2
      ],
      "name": "Nurudeen Oketade"
    },
    {
      "affs": [
        0
      ],
      "name": "Noa Bossel Ben-Moshe"
    },
    {
      "affs": [
        0,
        3,
        4
      ],
      "name": "Camilla Ciolli-Mattioli"
    },
    {
      "affs": [
        0
      ],
      "name": "Aryeh Solomon"
    },
    {
      "affs": [
        5
      ],
      "name": "Jay C. D. Hinton"
    },
    {
      "affs": [
        2
      ],
      "name": "Karen M. Dobos"
    },
    {
      "affs": [
        1,
        6
      ],
      "name": "David M. Lewinsohn"
    },
    {
      "affs": [
        0
      ],
      "name": "Shelly Hen-Avivi"
    },
    {
      "affs": [
        0
      ],
      "name": "Roi Avraham",
      "orcid": "0000-0002-9098-3885"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6eqjabsv1x9zr.bib",
  "cited_by": 0,
  "doi": "10.1371/journal.ppat.1014715",
  "fulltext_url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014715",
  "id": "6eqjabsv1x9zr",
  "issns": [
    "1553-7374",
    "1553-7366"
  ],
  "landing_url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014715",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "B Vitamins"
    ],
    [
      "heading",
      "Bacteria"
    ],
    [
      "heading",
      "Bacterial Diseases"
    ],
    [
      "heading",
      "Bacterial Pathogens"
    ],
    [
      "heading",
      "Biochemistry"
    ],
    [
      "heading",
      "Biology and Life Sciences"
    ],
    [
      "heading",
      "Biosynthesis"
    ],
    [
      "heading",
      "Cell Activation"
    ],
    [
      "heading",
      "Cell Biology"
    ],
    [
      "heading",
      "Cell Physiology"
    ],
    [
      "heading",
      "Chemical Compounds"
    ],
    [
      "heading",
      "Chemistry"
    ],
    [
      "heading",
      "Cytophotometry"
    ],
    [
      "heading",
      "Enterobacteriaceae"
    ],
    [
      "heading",
      "Enzyme-Linked Immunoassays"
    ],
    [
      "heading",
      "Flow Cytometry"
    ],
    [
      "heading",
      "Immune Response"
    ],
    [
      "heading",
      "Immunoassays"
    ],
    [
      "heading",
      "Immunologic Techniques"
    ],
    [
      "heading",
      "Immunology"
    ],
    [
      "heading",
      "Infectious Diseases"
    ],
    [
      "heading",
      "Medical Conditions"
    ],
    [
      "heading",
      "Medical Microbiology"
    ],
    [
      "heading",
      "Medicine and Health Sciences"
    ],
    [
      "heading",
      "Microbial Pathogens"
    ],
    [
      "heading",
      "Microbiology"
    ],
    [
      "heading",
      "Organic Chemistry"
    ],
    [
      "heading",
      "Organic Compounds"
    ],
    [
      "heading",
      "Organisms"
    ],
    [
      "heading",
      "Pathogens"
    ],
    [
      "heading",
      "Pathology and Laboratory Medicine"
    ],
    [
      "heading",
      "Physical Sciences"
    ],
    [
      "heading",
      "Research Article"
    ],
    [
      "heading",
      "Research and Analysis Methods"
    ],
    [
      "heading",
      "Riboflavin"
    ],
    [
      "heading",
      "Salmonella"
    ],
    [
      "heading",
      "Salmonellosis"
    ],
    [
      "heading",
      "Spectrophotometry"
    ],
    [
      "heading",
      "Spectrum Analysis Techniques"
    ],
    [
      "heading",
      "Vitamins"
    ],
    [
      "openalex",
      "1106|Salmonella and Campylobacter epidemiology"
    ],
    [
      "plos",
      "/Biology and life sciences/Biochemistry/Biosynthesis"
    ],
    [
      "plos",
      "/Biology and life sciences/Cell biology/Cell physiology/Cell activation"
    ],
    [
      "plos",
      "/Biology and life sciences/Immunology/Immune response"
    ],
    [
      "plos",
      "/Biology and life sciences/Microbiology/Medical microbiology/Microbial pathogens/Bacterial pathogens/Salmonella"
    ],
    [
      "plos",
      "/Biology and life sciences/Organisms/Bacteria/Enterobacteriaceae/Salmonella"
    ],
    [
      "plos",
      "/Medicine and health sciences/Immunology/Immune response"
    ],
    [
      "plos",
      "/Medicine and health sciences/Medical conditions/Infectious diseases/Bacterial diseases/Salmonella"
    ],
    [
      "plos",
      "/Medicine and health sciences/Medical conditions/Infectious diseases/Bacterial diseases/Salmonellosis"
    ],
    [
      "plos",
      "/Medicine and health sciences/Pathology and laboratory medicine/Pathogens/Microbial pathogens/Bacterial pathogens/Salmonella"
    ],
    [
      "plos",
      "/Physical sciences/Chemistry/Chemical compounds/Organic compounds/Vitamins/B vitamins/Riboflavin"
    ],
    [
      "plos",
      "/Physical sciences/Chemistry/Organic chemistry/Organic compounds/Vitamins/B vitamins/Riboflavin"
    ],
    [
      "plos",
      "/Research and analysis methods/Immunologic techniques/Immunoassays/Enzyme-linked immunoassays"
    ],
    [
      "plos",
      "/Research and analysis methods/Spectrum analysis techniques/Spectrophotometry/Cytophotometry/Flow cytometry"
    ]
  ],
  "openalex": "W7225166470",
  "pdf_url": "https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1014715&type=printable",
  "pmcid": "PMC13730361",
  "pmid": "42976164",
  "published": "2026-11-01",
  "publisher": "Public Library of Science",
  "ris": "https://research.draconitic.com/paper/6eqjabsv1x9zr.ris",
  "sources": [
    {
      "first_seen": "2026-11-04T12:20:43Z",
      "native_id": "10.1371/journal.ppat.1014715",
      "source": "plos",
      "url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014715"
    },
    {
      "first_seen": "2026-11-04T15:20:46Z",
      "native_id": "PMC:PMC13730361",
      "source": "europepmc",
      "url": "https://europepmc.org/article/PMC/PMC13730361"
    },
    {
      "first_seen": "2026-11-07T12:22:56Z",
      "native_id": "PMC13730361",
      "source": "pmc",
      "url": "https://doi.org/10.1371/journal.ppat.1014715"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "heading:Biochemistry",
      "subfield": "general"
    },
    {
      "field": "biology",
      "origin": "plos:cell biology",
      "subfield": "cell-biology"
    },
    {
      "field": "biology",
      "origin": "plos:immunology",
      "subfield": "immunology"
    },
    {
      "field": "biology",
      "origin": "heading:Microbiology",
      "subfield": "microbiology"
    },
    {
      "field": "medicine",
      "origin": "plos:infectious diseases",
      "subfield": "infectious-disease"
    }
  ],
  "title": "Modulation of riboflavin biosynthesis enzymes in non-typhoidal Salmonella isolates differentially impacts human MAIT cell activation",
  "title_text": "Modulation of riboflavin biosynthesis enzymes in non-typhoidal Salmonella isolates differentially impacts human MAIT cell activation",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T12:22:56Z",
  "url": "https://research.draconitic.com/paper/6eqjabsv1x9zr",
  "venue": "PLOS Pathogens",
  "versions": []
}