{
  "abstract": "Legionella pneumophila is the causative agent of Legionnaires’ disease, an accidental and severe form of pneumonia. The replication of L. pneumophila within alveolar macrophages requires the Dot/Icm type IV secretion system that translocates more than 330 bacterial effector proteins into the infected host cell. Many Dot/Icm effectors possess eukaryotic-like domains and manipulate host processes by functional mimicry. However, only a minority of effectors have been fully characterized. Redundancy among effector protein activities and host targets has complicated functional characterization of individual effector proteins. To explore the collective impact of Dot/Icm effectors on host cell processes, we created a library of 14 L. pneumophila genomic mutant strains lacking effector-rich regions (a total of 85 effector genes deleted) and used the multi-deletion mutants to interrogate host-pathogen interactions. While none of the mutants exhibited a defect in intracellular replication in THP-1 macrophages, several were attenuated in amoebae, including a mutant lacking a predicted amino acid transporter. In THP-1 cells, we observed that wild-type L. pneumophila 130b triggered a strong inflammatory and cellular stress transcriptional response in macrophages, whereas six mutants displayed reduced interferon signalling and one mutant displayed a marked decrease in the global expression of host heat shock response (HSR) genes. Through the creation of further sub-deletions, we found that the Dot/Icm effector kinase LegK4 was responsible for induction of the host HSR via the canonical transcription factor heat shock factor 1 (HSF1). Infection of THP-1 macrophages deficient in HSF1 revealed a potential role for the host HSR in the early stages of L. pneumophila infection. Together, these results reinforce the utility of multi-gene deletions to identify Dot/Icm effector phenotypes and the importance of the host HSR to L. pneumophila infection. Author summary: The bacterial pathogen Legionella pneumophila modulates host cell processes to replicate in human macrophages. Intracellular replication requires the Legionella Dot/Icm type IV secretion system that translocates more than 330 effector proteins into the infected macrophage that collectively enable intracellular replication. Here, we created a library of multi-effector deletion mutants to study the role of Dot/Icm effectors in the modulation of macrophage transcriptional responses during infection. While none of the mutants exhibited a defect in intracellular replication in THP-1 macrophages, several were attenuated in amoebae. Wild type L. pneumophila induced a strong host inflammatory and cell stress response in macrophages while some mutants produced a weaker response, despite similar levels of bacterial replication. We found that the effector protein LegK4 induced a global heat shock transcriptional response that was dependent on the host heat shock factor 1 (HSF1). Infection of HSF1-deficient macrophages with L. pneumophila suggested a potential role for HSF1 in the early stages of L. pneumophila infection.",
  "abstract_shown": true,
  "affiliations": [
    "Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia",
    "Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia",
    "Department of Molecular and Translational Science, Monash University, Clayton, Australia",
    "Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia"
  ],
  "article_type": "Research Article",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Raissa Wibawa"
    },
    {
      "affs": [
        0
      ],
      "name": "Pengfei Li"
    },
    {
      "affs": [
        0
      ],
      "name": "Linden J. Gearing"
    },
    {
      "affs": [
        1
      ],
      "name": "Sacha Pidot"
    },
    {
      "affs": [
        0
      ],
      "name": "Yuliia Faidiuk",
      "orcid": "0000-0003-2982-3919"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Wilson Wong"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Garrett Z. Ng"
    },
    {
      "affs": [
        0
      ],
      "name": "Kathleen McCaffrey"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Paul J. Hertzog"
    },
    {
      "affs": [
        3
      ],
      "name": "Shivani Pasricha"
    },
    {
      "affs": [
        0,
        2,
        3
      ],
      "name": "Elizabeth L. Hartland",
      "orcid": "0000-0003-4254-2863"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8tyfrf4wbxjax.bib",
  "cited_by": 0,
  "doi": "10.1371/journal.ppat.1014083",
  "fulltext_url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014083",
  "id": "8tyfrf4wbxjax",
  "issns": [
    "1553-7374",
    "1553-7366"
  ],
  "landing_url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014083",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Animal Cells"
    ],
    [
      "heading",
      "Bacteria"
    ],
    [
      "heading",
      "Bacterial Pathogens"
    ],
    [
      "heading",
      "Biology and Life Sciences"
    ],
    [
      "heading",
      "Blood Cells"
    ],
    [
      "heading",
      "Cell Biology"
    ],
    [
      "heading",
      "Cell Processes"
    ],
    [
      "heading",
      "Cellular Stress Responses"
    ],
    [
      "heading",
      "Cellular Types"
    ],
    [
      "heading",
      "Cloning"
    ],
    [
      "heading",
      "Deletion Mutagenesis"
    ],
    [
      "heading",
      "Gene Expression"
    ],
    [
      "heading",
      "Genetics"
    ],
    [
      "heading",
      "Genomics"
    ],
    [
      "heading",
      "Heat Shock Response"
    ],
    [
      "heading",
      "Immune Cells"
    ],
    [
      "heading",
      "Immunology"
    ],
    [
      "heading",
      "Legionella"
    ],
    [
      "heading",
      "Legionella Pneumophila"
    ],
    [
      "heading",
      "Macrophages"
    ],
    [
      "heading",
      "Medical Microbiology"
    ],
    [
      "heading",
      "Medicine and Health Sciences"
    ],
    [
      "heading",
      "Microbial Pathogens"
    ],
    [
      "heading",
      "Microbiology"
    ],
    [
      "heading",
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    ],
    [
      "heading",
      "Molecular Biology Techniques"
    ],
    [
      "heading",
      "Mutagenesis and Gene Deletion Techniques"
    ],
    [
      "heading",
      "Mutant Strains"
    ],
    [
      "heading",
      "Mutation"
    ],
    [
      "heading",
      "Organisms"
    ],
    [
      "heading",
      "Pathogens"
    ],
    [
      "heading",
      "Pathology and Laboratory Medicine"
    ],
    [
      "heading",
      "Research Article"
    ],
    [
      "heading",
      "Research and Analysis Methods"
    ],
    [
      "heading",
      "White Blood Cells"
    ],
    [
      "openalex",
      "1310|Legionella and Acanthamoeba research"
    ],
    [
      "plos",
      "/Biology and life sciences/Cell biology/Cell processes/Cellular stress responses/Heat shock response"
    ],
    [
      "plos",
      "/Biology and life sciences/Cell biology/Cellular types/Animal cells/Blood cells/White blood cells/Macrophages"
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    [
      "plos",
      "/Biology and life sciences/Cell biology/Cellular types/Animal cells/Immune cells/White blood cells/Macrophages"
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    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Genomics"
    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Mutation/Mutant strains"
    ],
    [
      "plos",
      "/Biology and life sciences/Immunology/Immune cells/White blood cells/Macrophages"
    ],
    [
      "plos",
      "/Biology and life sciences/Microbiology/Medical microbiology/Microbial pathogens/Bacterial pathogens/Legionella/Legionella pneumophila"
    ],
    [
      "plos",
      "/Biology and life sciences/Molecular biology/Molecular biology techniques/Cloning"
    ],
    [
      "plos",
      "/Biology and life sciences/Molecular biology/Molecular biology techniques/Mutagenesis and gene deletion techniques/Deletion mutagenesis"
    ],
    [
      "plos",
      "/Biology and life sciences/Organisms/Bacteria/Legionella/Legionella pneumophila"
    ],
    [
      "plos",
      "/Medicine and health sciences/Immunology/Immune cells/White blood cells/Macrophages"
    ],
    [
      "plos",
      "/Medicine and health sciences/Pathology and laboratory medicine/Pathogens/Microbial pathogens/Bacterial pathogens/Legionella/Legionella pneumophila"
    ],
    [
      "plos",
      "/Research and analysis methods/Molecular biology techniques/Cloning"
    ],
    [
      "plos",
      "/Research and analysis methods/Molecular biology techniques/Mutagenesis and gene deletion techniques/Deletion mutagenesis"
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  "openalex": "W7223219583",
  "pdf_url": "https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1014083&type=printable",
  "pmcid": "PMC13712724",
  "pmid": "42911972",
  "published": "2026-10-22",
  "publisher": "Public Library of Science",
  "ris": "https://research.draconitic.com/paper/8tyfrf4wbxjax.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:23Z",
      "native_id": "10.1371/journal.ppat.1014083",
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      "url": "https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014083"
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    {
      "first_seen": "2026-10-31T12:23:15Z",
      "native_id": "PMC13712724",
      "source": "pmc",
      "url": "https://doi.org/10.1371/journal.ppat.1014083"
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  "subjects": [
    {
      "field": "biochemistry",
      "origin": "plos:gene expression",
      "subfield": "molecular-biology"
    },
    {
      "field": "biology",
      "origin": "plos:cell biology",
      "subfield": "cell-biology"
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    {
      "field": "biology",
      "origin": "plos:genomics",
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      "field": "biology",
      "origin": "heading:Immunology",
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      "field": "medicine",
      "origin": "heading:Medicine and Health Sciences",
      "subfield": "general"
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  ],
  "title": "Multi-Dot/Icm effector mutants reveal distinct host responses in Legionella infected macrophages",
  "title_text": "Multi-Dot/Icm effector mutants reveal distinct host responses in Legionella infected macrophages",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T12:23:15Z",
  "url": "https://research.draconitic.com/paper/8tyfrf4wbxjax",
  "venue": "PLOS Pathogens",
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}