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Andrews K, Landeryou T, Sicheritz-Pontén T, Nale JY. Diverse Prophage Elements of Salmonella enterica Serovars Show Potential Roles in Bacterial Pathogenicity. Cells 2024; 13:514. [PMID: 38534358 DOI: 10.3390/cells13060514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/26/2024] [Accepted: 03/08/2024] [Indexed: 03/28/2024] Open
Abstract
Nontyphoidal salmonellosis is an important foodborne and zoonotic infection that causes significant global public health concern. Diverse serovars are multidrug-resistant and encode several virulence indicators; however, little is known on the role prophages play in driving these traits. Here, we extracted prophages from seventy-five Salmonella genomes which represent the fifteen important serovars in the United Kingdom. We analyzed the intact prophages for the presence of virulence genes and established their genomic relationships. We identified 615 prophages from the Salmonella strains, from which 195 prophages are intact, 332 are incomplete, while 88 are questionable. The average prophage carriage was found to be 'extreme' in S. Heidelberg, S. Inverness, and S. Newport (10.2-11.6 prophages/strain), 'high' in S. Infantis, S. Stanley, S. Typhimurium, and S. Virchow (8.2-9.0 prophages/strain), 'moderate' in S. Agona, S. Braenderup, S. Bovismorbificans, S. Choleraesuis, S. Dublin, and S. Java (6.0-7.8 prophages/strain), and 'low' in S. Javiana and S. Enteritidis (5.8 prophages/strain). Cumulatively, 61 virulence genes (1500 gene copies) were detected from representative intact prophages and linked to Salmonella delivery/secretion system (42.62%), adherence (32.7%), magnesium uptake (3.88%), regulation (5%), stress/survival (1.6%), toxins (10%), and antivirulence (1.6%). Diverse clusters were formed among the intact prophages and with bacteriophages of other enterobacteria, suggesting different lineages and associations. Our work provides a strong body of data to support the contributions diverse prophages make to the pathogenicity of Salmonella, including thirteen previously unexplored serovars.
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Affiliation(s)
- Kirstie Andrews
- Centre for Epidemiology and Planetary Health, School of Veterinary Medicine, Scotland's Rural College, Inverness IV2 5NA, UK
| | - Toby Landeryou
- Centre for Epidemiology and Planetary Health, School of Veterinary Medicine, Scotland's Rural College, Inverness IV2 5NA, UK
| | - Thomas Sicheritz-Pontén
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, 1353 Copenhagen, Denmark
| | - Janet Yakubu Nale
- Centre for Epidemiology and Planetary Health, School of Veterinary Medicine, Scotland's Rural College, Inverness IV2 5NA, UK
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2
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Lefrançois LH, Nitschke J, Wu H, Panis G, Prados J, Butler RE, Mendum TA, Hanna N, Stewart GR, Soldati T. Temporal genome-wide fitness analysis of Mycobacterium marinum during infection reveals the genetic requirement for virulence and survival in amoebae and microglial cells. mSystems 2024; 9:e0132623. [PMID: 38270456 PMCID: PMC10878075 DOI: 10.1128/msystems.01326-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 12/15/2023] [Indexed: 01/26/2024] Open
Abstract
Tuberculosis remains the most pervasive infectious disease and the recent emergence of drug-resistant strains emphasizes the need for more efficient drug treatments. A key feature of pathogenesis, conserved between the human pathogen Mycobacterium tuberculosis and the model pathogen Mycobacterium marinum, is the metabolic switch to lipid catabolism and altered expression of virulence genes at different stages of infection. This study aims to identify genes involved in sustaining viable intracellular infection. We applied transposon sequencing (Tn-Seq) to M. marinum, an unbiased genome-wide strategy combining saturation insertional mutagenesis and high-throughput sequencing. This approach allowed us to identify the localization and relative abundance of insertions in pools of transposon mutants. Gene essentiality and fitness cost of mutations were quantitatively compared between in vitro growth and different stages of infection in two evolutionary distinct phagocytes, the amoeba Dictyostelium discoideum and the murine BV2 microglial cells. In the M. marinum genome, 57% of TA sites were disrupted and 568 genes (10.2%) were essential, which is comparable to previous Tn-Seq studies on M. tuberculosis and M. bovis. Major pathways involved in the survival of M. marinum during infection of D. discoideum are related to DNA damage repair, lipid and vitamin metabolism, the type VII secretion system (T7SS) ESX-1, and the Mce1 lipid transport system. These pathways, except Mce1 and some glycolytic enzymes, were similarly affected in BV2 cells. These differences suggest subtly distinct nutrient availability or requirement in different host cells despite the known predominant use of lipids in both amoeba and microglial cells.IMPORTANCEThe emergence of biochemically and genetically tractable host model organisms for infection studies holds the promise to accelerate the pace of discoveries related to the evolution of innate immunity and the dissection of conserved mechanisms of cell-autonomous defenses. Here, we have used the genetically and biochemically tractable infection model system Dictyostelium discoideum/Mycobacterium marinum to apply a genome-wide transposon-sequencing experimental strategy to reveal comprehensively which mutations confer a fitness advantage or disadvantage during infection and compare these to a similar experiment performed using the murine microglial BV2 cells as host for M. marinum to identify conservation of virulence pathways between hosts.
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Affiliation(s)
- Louise H. Lefrançois
- Department of Biochemistry, Faculty of Science, University of Geneva, Science II, Geneva, Switzerland
| | - Jahn Nitschke
- Department of Biochemistry, Faculty of Science, University of Geneva, Science II, Geneva, Switzerland
| | - Huihai Wu
- Department of Microbial Sciences, School of Biosciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/CMU, University of Geneva, Institute of Genetics and Genomics in Geneva (iGE3), Genève, Switzerland
| | - Julien Prados
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/CMU, University of Geneva, Institute of Genetics and Genomics in Geneva (iGE3), Genève, Switzerland
- Bioinformatics Support Platform for data analysis, Geneva University, Medicine Faculty, Geneva, Switzerland
| | - Rachel E. Butler
- Department of Microbial Sciences, School of Biosciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Tom A. Mendum
- Department of Microbial Sciences, School of Biosciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Nabil Hanna
- Department of Biochemistry, Faculty of Science, University of Geneva, Science II, Geneva, Switzerland
| | - Graham R. Stewart
- Department of Microbial Sciences, School of Biosciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Science, University of Geneva, Science II, Geneva, Switzerland
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3
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Eshraghisamani R, Mirto AJ, Wang J, Behr MA, Barkema HW, De Buck J. Identification of essential genes in Mycobacterium avium subsp. paratuberculosis genome for persistence in dairy calves. Front Microbiol 2022; 13:994421. [PMID: 36338087 PMCID: PMC9631821 DOI: 10.3389/fmicb.2022.994421] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/05/2022] [Indexed: 11/02/2023] Open
Abstract
To cause disease Mycobacterium avium subsp. paratuberculosis needs to enter mammalian cells, arrest phagosomal maturation and manipulate the host immune system. The genetic basis of the bacterial capacity to achieve these outcomes remains largely unknown. Identifying these genes would allow us to gain a deeper understanding of MAP's pathogenesis and potentially develop a live attenuated Johne's disease vaccine by knocking out these genes. MAP genes demonstrated to be essential for colonization in the natural host, ruminants, are unknown. Genome-wide transposon mutagenesis and high-throughput sequencing were combined to evaluate the essentiality of each coding region in the bacterial genome to survive in dairy calves. A saturated library of 3,852 MAP Tn mutants, with insertions in 56% of TA sites, interrupting 88% of genes, was created using a MycoMarT7 phagemid containing a mariner transposon. Six calves were inoculated with a high dose of a library of MAP mutants, 1011 CFUs, (input) at 2 weeks of age. Following 2 months of incubation, MAP cells were isolated from the ileum, jejunum, and their associated lymph nodes of calves, resulting in approximately 100,000 colonies grown on solid media across 6 animals (output). Targeted next-generation sequencing was used to identify the disrupted genes in all the mutants in the input pool and the output pool recovered from the tissues to identify in vivo essential genes. Statistical analysis for the determination of essential genes was performed by a Hidden Markov Model (HMM), categorizing genes into essential genes that are devoid of insertions and growth-defect genes whose disruption impairs the growth of the organism. Sequence analysis identified 430 in vivo essential and 260 in vivo growth-defect genes. Gene ontology enrichment analysis of the in vivo essential and growth-defect genes with the highest reduction in the tissues revealed a high representation of genes involved in metabolism and respiration, cell wall and cell processing, virulence, and information pathway processes. This study has systematically identified essential genes for the growth and persistence of MAP in the natural host body.
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Affiliation(s)
- Razieh Eshraghisamani
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Amanda J. Mirto
- Environmental Health and Safety, University of Wisconsin-Madison, Madison, WI, United States
| | - Joyce Wang
- Department of Medicine, Faculty of Medicine, Health Centre, McGill University, Montréal, QC, Canada
| | - Marcel A. Behr
- Department of Medicine, Faculty of Medicine, Health Centre, McGill University, Montréal, QC, Canada
| | - Herman W. Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Jeroen De Buck
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
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4
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Mizzi R, Plain KM, Whittington R, Timms VJ. Global Phylogeny of Mycobacterium avium and Identification of Mutation Hotspots During Niche Adaptation. Front Microbiol 2022; 13:892333. [PMID: 35602010 PMCID: PMC9121174 DOI: 10.3389/fmicb.2022.892333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/06/2022] [Indexed: 12/27/2022] Open
Abstract
Mycobacterium avium is separated into four subspecies: M. avium subspecies avium (MAA), M. avium subspecies silvaticum (MAS), M. avium subspecies hominissuis (MAH), and M. avium subspecies paratuberculosis (MAP). Understanding the mechanisms of host and tissue adaptation leading to their clinical significance is vital to reduce the economic, welfare, and public health concerns associated with diseases they may cause in humans and animals. Despite substantial phenotypic diversity, the subspecies nomenclature is controversial due to high genetic similarity. Consequently, a set of 1,230 M. avium genomes was used to generate a phylogeny, investigate SNP hotspots, and identify subspecies-specific genes. Phylogeny reiterated the findings from previous work and established that Mycobacterium avium is a species made up of one highly diverse subspecies, known as MAH, and at least two clonal pathogens, named MAA and MAP. Pan-genomes identified coding sequences unique to each subspecies, and in conjunction with a mapping approach, mutation hotspot regions were revealed compared to the reference genomes for MAA, MAH, and MAP. These subspecies-specific genes may serve as valuable biomarkers, providing a deeper understanding of genetic differences between M. avium subspecies and the virulence mechanisms of mycobacteria. Furthermore, SNP analysis demonstrated common regions between subspecies that have undergone extensive mutations during niche adaptation. The findings provide insights into host and tissue specificity of this genetically conserved but phenotypically diverse species, with the potential to provide new diagnostic targets and epidemiological and therapeutic advances.
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Affiliation(s)
- Rachel Mizzi
- Farm Animal Health, School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW, Australia
| | - Karren M Plain
- Farm Animal Health, School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW, Australia.,Microbiology and Parasitology Research, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, Australia
| | - Richard Whittington
- Farm Animal Health, School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW, Australia
| | - Verlaine J Timms
- Neilan Laboratory of Microbial and Molecular Diversity, College of Engineering, Science and Environment, The University of Newcastle, Newcastle, NSW, Australia
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5
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Rendón JM, Lang B, Tartaglia GG, Burgas MT. BacFITBase: a database to assess the relevance of bacterial genes during host infection. Nucleic Acids Res 2020; 48:D511-D516. [PMID: 31665505 PMCID: PMC7145566 DOI: 10.1093/nar/gkz931] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 11/24/2022] Open
Abstract
Bacterial infections have been on the rise world-wide in recent years and have a considerable impact on human well-being in terms of attributable deaths and disability-adjusted life years. Yet many mechanisms underlying bacterial pathogenesis are still poorly understood. Here, we introduce the BacFITBase database for the systematic characterization of bacterial proteins relevant for host infection aimed to enable the identification of new antibiotic targets. BacFITBase is manually curated and contains more than 90 000 entries with information on the contribution of individual genes to bacterial fitness under in vivo infection conditions in a range of host species. The data were collected from 15 different studies in which transposon mutagenesis was performed, including top-priority pathogens such as Acinetobacter baumannii and Campylobacter jejuni, for both of which increasing antibiotic resistance has been reported. Overall, BacFITBase includes information on 15 pathogenic bacteria and 5 host vertebrates across 10 different tissues. It is freely available at www.tartaglialab.com/bacfitbase.
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Affiliation(s)
- Javier Macho Rendón
- Systems Biology of Infection Lab, Department of Biochemistry and Molecular Biology, Biosciences Faculty, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | - Benjamin Lang
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Gian Gaetano Tartaglia
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain.,ICREA, 23 Passeig Lluis Companys 08010 and Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.,Department of Biology 'Charles Darwin', Sapienza University of Rome, P.le A. Moro 5, Rome 00185, Italy.,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Marc Torrent Burgas
- Systems Biology of Infection Lab, Department of Biochemistry and Molecular Biology, Biosciences Faculty, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
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6
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Shoyama FM, Janetanakit T, Bannantine JP, Barletta RG, Sreevatsan S. Elucidating the Regulon of a Fur -like Protein in Mycobacterium avium subsp. paratuberculosis ( MAP). Front Microbiol 2020; 11:598. [PMID: 32390963 PMCID: PMC7192006 DOI: 10.3389/fmicb.2020.00598] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/18/2020] [Indexed: 11/13/2022] Open
Abstract
Intracellular iron concentration is tightly regulated to maintain cell viability. Iron plays important roles in electron transport, nucleic acid synthesis, and oxidative stress. A Mycobacterium avium subsp. paratuberculosis (MAP)-specific genomic island carries a putative metal transport operon that includes MAP3773c, which encodes a Fur-like protein. Although well characterized as a global regulator of iron homeostasis in multiple bacteria, the function of Fur (ferric uptake regulator) in MAP is unknown as this organism also carries IdeR (iron dependent regulator), a native iron regulatory protein specific to mycobacteria. Computational analysis using PRODORIC identified 23 different pathways involved in respiration, metabolism, and virulence that were likely regulated by MAP3773c. Thus, chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) was performed to confirm the putative regulon of MAP3773c (Fur-like protein) in MAP. ChIP-Seq revealed enriched binding to 58 regions by Fur under iron-replete and -deplete conditions, located mostly within open reading frames (ORFs). Three ChIP peaks were identified in genes that are directly related to iron regulation: MAP3638c (hemophore-like protein), MAP3736c (Fur box), and MAP3776c (ABC transporter). Fur box consensus sequence was identified, and binding specificity and dependence on Mn2+ availability was confirmed by a chemiluminescent electrophoresis mobility shift assay (EMSA). The results confirmed that MAP3773c is a Fur ortholog that recognizes a 19 bp DNA sequence motif (Fur box) and it is involved in metal homeostasis. This work provides a regulatory network of MAP Fur binding sites during iron-replete and -deplete conditions, highlighting unique properties of Fur regulon in MAP.
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Affiliation(s)
- Fernanda Miyagaki Shoyama
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
| | - Taveesak Janetanakit
- Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - John P. Bannantine
- National Animal Disease Center, USDA-Agricultural Research Service, Ames, IA, United States
| | - Raul G. Barletta
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, United States
| | - Srinand Sreevatsan
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
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7
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Budell WC, Germain GA, Janisch N, McKie-Krisberg Z, Jayaprakash AD, Resnick AE, Quadri LEN. Transposon mutagenesis in Mycobacterium kansasii links a small RNA gene to colony morphology and biofilm formation and identifies 9,885 intragenic insertions that do not compromise colony outgrowth. Microbiologyopen 2020; 9:e988. [PMID: 32083796 PMCID: PMC7142372 DOI: 10.1002/mbo3.988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 01/05/2023] Open
Abstract
Mycobacterium kansasii (Mk) is a resilient opportunistic human pathogen that causes tuberculosis‐like chronic pulmonary disease and mortality stemming from comorbidities and treatment failure. The standard treatment of Mk infections requires costly, long‐term, multidrug courses with adverse side effects. The emergence of drug‐resistant isolates further complicates the already challenging drug therapy regimens and threatens to compromise the future control of Mk infections. Despite the increasingly recognized global burden of Mk infections, the biology of this opportunistic pathogen remains essentially unexplored. In particular, studies reporting gene function or generation of defined mutants are scarce. Moreover, no transposon (Tn) mutagenesis tool has been validated for use in Mk, a situation limiting the repertoire of genetic approaches available to accelerate the dissection of gene function and the generation of gene knockout mutants in this poorly characterized pathogen. In this study, we validated the functionality of a powerful Tn mutagenesis tool in Mk and used this tool in conjunction with a forward genetic screen to establish a previously unrecognized role of a conserved mycobacterial small RNA gene of unknown function in colony morphology features and biofilm formation. We also combined Tn mutagenesis with next‐generation sequencing to identify 12,071 Tn insertions that do not compromise viability in vitro. Finally, we demonstrated the susceptibility of the Galleria mellonella larva to Mk, setting the stage for further exploration of this simple and economical infection model system to the study of this pathogen.
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Affiliation(s)
- William C Budell
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Gabrielle A Germain
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Niklas Janisch
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Zaid McKie-Krisberg
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA
| | | | - Andrew E Resnick
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA
| | - Luis E N Quadri
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA.,Biochemistry Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
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8
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Hemati Z, Derakhshandeh A, Haghkhah M, Chaubey KK, Gupta S, Singh M, Singh SV, Dhama K. Mammalian cell entry operons; novel and major subset candidates for diagnostics with special reference to Mycobacterium avium subspecies paratuberculosis infection. Vet Q 2020; 39:65-75. [PMID: 31282842 PMCID: PMC6830979 DOI: 10.1080/01652176.2019.1641764] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mammalian cell entry (mce) genes are the components of the mce operon and play a vital role in the entry of Mycobacteria into the mammalian cell and their survival within phagocytes and epithelial cells. Mce operons are present in the DNA of Mycobacteria and translate proteins associated with the invasion and long-term existence of these pathogens in macrophages. The exact mechanism of action of mce genes and their functions are not clear yet. However, with the loss of these genes Mycobacteria lose their pathogenicity. Mycobacterium avium subspecies paratuberculosis (MAP), the etiological agent of Johne’s disease, is the cause of chronic enteritis of animals and significantly affects economic impact on the livestock industry. Since MAP is not inactivated during pasteurization, human population is continuously at the risk of getting exposed to MAP infection through consumption of dairy products. There is need for new candidate genes and/or proteins for developing improved diagnostic assays for the diagnosis of MAP infection and for the control of disease. Increasing evidences showed that expression of mce genes is important for the virulence of MAP. Whole-genome DNA microarray representing MAP revealed that there are 14 large sequence polymorphisms with LSPP12 being the most widely conserved MAP-specific region that included a cluster of six homologs of mce-family involved in lipid metabolism. On the other hand, LSP11 comprising part of mce2 operon was absent in MAP isolates. This review summarizes the advancement of research on mce genes of Mycobacteria with special reference to the MAP infection.
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Affiliation(s)
- Zahra Hemati
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University , Shiraz , Iran
| | - Abdollah Derakhshandeh
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University , Shiraz , Iran
| | - Masoud Haghkhah
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University , Shiraz , Iran
| | - Kundan Kumar Chaubey
- Department of Biotechnology, Institute of Applied Sciences and Humanities, GLA University , Mathura , India
| | - Saurabh Gupta
- Department of Biotechnology, Institute of Applied Sciences and Humanities, GLA University , Mathura , India
| | - Manju Singh
- Department of Biotechnology, Institute of Applied Sciences and Humanities, GLA University , Mathura , India
| | - Shoorvir V Singh
- Department of Biotechnology, Institute of Applied Sciences and Humanities, GLA University , Mathura , India
| | - Kuldeep Dhama
- Department of Pathology, Indian Veterinary Research Institute , Bareilly , India
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9
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Global Assessment of Mycobacterium avium subsp. hominissuis Genetic Requirement for Growth and Virulence. mSystems 2019; 4:4/6/e00402-19. [PMID: 31822597 PMCID: PMC6906737 DOI: 10.1128/msystems.00402-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nontuberculous mycobacterial infections caused by the opportunistic pathogen Mycobacterium avium subsp. hominissuis (MAH) are currently receiving renewed attention due to increased incidence combined with difficult treatment. Insights into the disease-causing mechanisms of this species have been hampered by difficulties in genetic manipulation of the bacteria. Here, we identified and sequenced a highly transformable, virulent MAH clinical isolate susceptible to high-density transposon mutagenesis, facilitating global gene disruption and subsequent investigation of MAH gene function. By transposon insertion sequencing (TnSeq) of this strain, we defined the MAH genome-wide genetic requirement for virulence and in vitro growth and organized ∼3,500 identified transposon mutants for hypothesis-driven research. The majority (96%) of the genes we identified as essential for MAH in vitro had a mutual ortholog in the related and highly virulent Mycobacterium tuberculosis (Mtb). However, passaging our library through a mouse model of infection revealed a substantial number (54% of total hits) of novel virulence genes. More than 97% of the MAH virulence genes had a mutual ortholog in Mtb Finally, we validated novel genes required for successful MAH infection: one encoding a probable major facilitator superfamily (MFS) transporter and another encoding a hypothetical protein located in the immediate vicinity of six other identified virulence genes. In summary, we provide new, fundamental insights into the underlying genetic requirement of MAH for growth and host infection.IMPORTANCE Pulmonary disease caused by nontuberculous mycobacteria is increasing worldwide. The majority of these infections are caused by the Mycobacterium avium complex (MAC), whereof >90% are due to Mycobacterium avium subsp. hominissuis (MAH). Treatment of MAH infections is currently difficult, with a combination of antibiotics given for at least 12 months. To control MAH by improved therapy, prevention, and diagnostics, we need to understand the underlying mechanisms of infection. Here, we provide crucial insights into MAH's global genetic requirements for growth and infection. We find that the vast majority of genes required for MAH growth and virulence (96% and 97%, respectively) have mutual orthologs in the tuberculosis-causing pathogen M. tuberculosis (Mtb). However, we also find growth and virulence genes specific to MAC species. Finally, we validate novel mycobacterial virulence factors that might serve as future drug targets for MAH-specific treatment or translate to broader treatment of related mycobacterial diseases.
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10
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Yang J, Luo X, Yan T, Lin X. Recovery of cesium from saline lake brine with potassium cobalt hexacyanoferrate-modified chrome-tanned leather scrap adsorbent. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.10.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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11
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Rathnaiah G, Zinniel DK, Bannantine JP, Stabel JR, Gröhn YT, Collins MT, Barletta RG. Pathogenesis, Molecular Genetics, and Genomics of Mycobacterium avium subsp. paratuberculosis, the Etiologic Agent of Johne's Disease. Front Vet Sci 2017; 4:187. [PMID: 29164142 PMCID: PMC5681481 DOI: 10.3389/fvets.2017.00187] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/20/2017] [Indexed: 12/12/2022] Open
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of Johne's disease in ruminants causing chronic diarrhea, malnutrition, and muscular wasting. Neonates and young animals are infected primarily by the fecal-oral route. MAP attaches to, translocates via the intestinal mucosa, and is phagocytosed by macrophages. The ensuing host cellular immune response leads to granulomatous enteritis characterized by a thick and corrugated intestinal wall. We review various tissue culture systems, ileal loops, and mice, goats, and cattle used to study MAP pathogenesis. MAP can be detected in clinical samples by microscopy, culturing, PCR, and an enzyme-linked immunosorbent assay. There are commercial vaccines that reduce clinical disease and shedding, unfortunately, their efficacies are limited and may not engender long-term protective immunity. Moreover, the potential linkage with Crohn's disease and other human diseases makes MAP a concern as a zoonotic pathogen. Potential therapies with anti-mycobacterial agents are also discussed. The completion of the MAP K-10 genome sequence has greatly improved our understanding of MAP pathogenesis. The analysis of this sequence has identified a wide range of gene functions involved in virulence, lipid metabolism, transcriptional regulation, and main metabolic pathways. We also review the transposons utilized to generate random transposon mutant libraries and the recent advances in the post-genomic era. This includes the generation and characterization of allelic exchange mutants, transcriptomic analysis, transposon mutant banks analysis, new efforts to generate comprehensive mutant libraries, and the application of transposon site hybridization mutagenesis and transposon sequencing for global analysis of the MAP genome. Further analysis of candidate vaccine strains development is also provided with critical discussions on their benefits and shortcomings, and strategies to develop a highly efficacious live-attenuated vaccine capable of differentiating infected from vaccinated animals.
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Affiliation(s)
- Govardhan Rathnaiah
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, United States
| | - Denise K. Zinniel
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, United States
| | - John P. Bannantine
- Infectious Bacterial Diseases, National Animal Disease Center, USDA-ARS, Ames, IA, United States
| | - Judith R. Stabel
- Infectious Bacterial Diseases, National Animal Disease Center, USDA-ARS, Ames, IA, United States
| | - Yrjö T. Gröhn
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Michael T. Collins
- Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Raúl G. Barletta
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, United States
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12
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Barkema HW, Orsel K, Nielsen SS, Koets AP, Rutten VPMG, Bannantine JP, Keefe GP, Kelton DF, Wells SJ, Whittington RJ, Mackintosh CG, Manning EJ, Weber MF, Heuer C, Forde TL, Ritter C, Roche S, Corbett CS, Wolf R, Griebel PJ, Kastelic JP, De Buck J. Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection. Transbound Emerg Dis 2017; 65 Suppl 1:125-148. [PMID: 28941207 DOI: 10.1111/tbed.12723] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Indexed: 12/17/2022]
Abstract
In the last decades, many regional and country-wide control programmes for Johne's disease (JD) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within-farm and farm-to-farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps.
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Affiliation(s)
- H W Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - K Orsel
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - S S Nielsen
- University of Copenhagen, Copenhagen, Denmark
| | - A P Koets
- Utrecht University, Utrecht, The Netherlands.,Wageningen Bioveterinary Research, Wageningen, The Netherlands
| | - V P M G Rutten
- Utrecht University, Utrecht, The Netherlands.,Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa
| | | | - G P Keefe
- University of Prince Edward Island, Charlottetown, Canada
| | | | - S J Wells
- University of Minnesota, Minneapolis, MN, USA
| | | | | | | | - M F Weber
- GD Animal Health, Deventer, The Netherlands
| | - C Heuer
- Massey University, Palmerston North, New Zealand
| | | | - C Ritter
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - S Roche
- University of Guelph, Guelph, Canada
| | - C S Corbett
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - R Wolf
- Amt der Steiermärkischen Landesregierung, Graz, Austria
| | | | - J P Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - J De Buck
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
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13
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Rathnaiah G, Bannantine JP, Bayles DO, Zinniel DK, Stabel JR, Gröhn YT, Barletta RG. Analysis of Mycobacterium avium subsp. paratuberculosis mutant libraries reveals loci-dependent transposition biases and strategies for novel mutant discovery. MICROBIOLOGY-SGM 2016; 162:633-641. [PMID: 26888023 DOI: 10.1099/mic.0.000258] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP), the aetiological agent of Johne's disease, is one of the most important bacterial pathogens in ruminants. A thorough understanding of MAP pathogenesis is needed to develop new vaccines and diagnostic tests. The generation of comprehensive random transposon mutant libraries is a fundamental genetic technology to determine the role of genes in physiology and pathogenesis. In this study, whole MAP genome analysis compared the insertion sites for the mycobacterial transposon Tn5367 derived from the Mycobacterium smegmatis insertion sequence IS1096 and the mariner transposon MycoMarT7 carrying the Himar1 transposase. We determined that only MycoMarT7 provides a random representation of insertions in 99 % of all MAP genes. Analysis of the MAP K-10 genome indicated that 710 of all ORFs do not possess IS1096 recognition sites, while only 37 do not have the recognition site for MycoMarT7. Thus, a significant number of MAP genes remain underrepresented in insertion libraries from IS1096-derived transposons. Analysis of MycoMarT7 and Tn5367 mutants showed that Tn5367 has a predilection to insert within intergenic regions, suggesting that MycoMarT7 is the more adequate for generating a comprehensive library. However, we uncovered the novel finding that both transposons have loci-dependent biases, with Tn5367 being the most skewed. These loci-dependent transposition biases led to an underestimation of the number of independent mutants required to generate a comprehensive mutant library, leading to an overestimation of essential genes. Herein, we also demonstrated a useful platform for gene discovery and analysis by isolating three novel mutants for each transposon.
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Affiliation(s)
- Govardhan Rathnaiah
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE,USA
| | - John P Bannantine
- Infectious Bacterial Diseases, National Animal Disease Center, United States Department of Agriculture - Agricultural Research Service, Ames, IA, USA
| | - Darrell O Bayles
- Infectious Bacterial Diseases, National Animal Disease Center, United States Department of Agriculture - Agricultural Research Service, Ames, IA, USA
| | - Denise K Zinniel
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE,USA
| | - Judith R Stabel
- Infectious Bacterial Diseases, National Animal Disease Center, United States Department of Agriculture - Agricultural Research Service, Ames, IA, USA
| | - Yrjö T Gröhn
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, NY, USA
| | - Raúl G Barletta
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE,USA
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14
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Iron Acquisition in Mycobacterium avium subsp. paratuberculosis. J Bacteriol 2015; 198:857-66. [PMID: 26712939 PMCID: PMC4810606 DOI: 10.1128/jb.00922-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 12/18/2015] [Indexed: 01/26/2023] Open
Abstract
Mycobacterium avium subsp. paratuberculosis is a host-adapted pathogen that evolved from the environmental bacterium M. avium subsp. hominissuis through gene loss and gene acquisition. Growth of M. avium subsp. paratuberculosis in the laboratory is enhanced by supplementation of the media with the iron-binding siderophore mycobactin J. Here we examined the production of mycobactins by related organisms and searched for an alternative iron uptake system in M. avium subsp. paratuberculosis. Through thin-layer chromatography and radiolabeled iron-uptake studies, we showed that M. avium subsp. paratuberculosis is impaired for both mycobactin synthesis and iron acquisition. Consistent with these observations, we identified several mutations, including deletions, in M. avium subsp. paratuberculosis genes coding for mycobactin synthesis. Using a transposon-mediated mutagenesis screen conditional on growth without myobactin, we identified a potential mycobactin-independent iron uptake system on a M. avium subsp. paratuberculosis-specific genomic island, LSPP15. We obtained a transposon (Tn) mutant with a disruption in the LSPP15 gene MAP3776c for targeted study. The mutant manifests increased iron uptake as well as intracellular iron content, with genes downstream of the transposon insertion (MAP3775c to MAP3772c [MAP3775-2c]) upregulated as the result of a polar effect. As an independent confirmation, we observed the same iron uptake phenotypes by overexpressing MAP3775-2c in wild-type M. avium subsp. paratuberculosis. These data indicate that the horizontally acquired LSPP15 genes contribute to iron acquisition by M. avium subsp. paratuberculosis, potentially allowing the subsequent loss of siderophore production by this pathogen. IMPORTANCE Many microbes are able to scavenge iron from their surroundings by producing iron-chelating siderophores. One exception is Mycobacterium avium subsp. paratuberculosis, a fastidious, slow-growing animal pathogen whose growth needs to be supported by exogenous mycobacterial siderophore (mycobactin) in the laboratory. Data presented here demonstrate that, compared to other closely related M. avium subspecies, mycobactin production and iron uptake are different in M. avium subsp. paratuberculosis, and these phenotypes may be caused by numerous deletions in its mycobactin biosynthesis pathway. Using a genomic approach, supplemented by targeted genetic and biochemical studies, we identified that LSPP15, a horizontally acquired genomic island, may encode an alternative iron uptake system. These findings shed light on the potential physiological consequence of horizontal gene transfer in M. avium subsp. paratuberculosis evolution.
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15
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Genetic diversity of Mycobacterium avium subspecies paratuberculosis and the influence of strain type on infection and pathogenesis: a review. Vet Res 2015; 46:64. [PMID: 26092160 PMCID: PMC4473831 DOI: 10.1186/s13567-015-0203-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/16/2015] [Indexed: 12/12/2022] Open
Abstract
Mycobacterium avium subspecies paratuberculosis (Map) is an important pathogen that causes a chronic, progressive granulomatous enteritis known as Johne's disease or paratuberculosis. The disease is endemic in many parts of the world and responsible for considerable losses to the livestock and associated industries. Diagnosis and control are problematic, due mostly to the long incubation period of the disease when infected animals show no clinical signs and are difficult to detect, and the ability of the organism to survive and persist in the environment. The existence of phenotypically distinct strains of Map has been known since the 1930s but the genetic differentiation of Map strain types has been challenging and only recent technologies have proven sufficiently discriminative for strain comparisons, tracing the sources of infection and epidemiological studies. It is important to understand the differences that exist between Map strains and how they influence both development and transmission of disease. This information is required to develop improved diagnostics and effective vaccines for controlling Johne's disease. Here I review the current classification of Map strain types, the sources of the genetic variability within strains, growth characteristics and epidemiological traits associated with strain type and the influence of strain type on infection and pathogenicity.
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16
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Identification of a lineage specific zinc responsive genomic island in Mycobacterium avium ssp. paratuberculosis. BMC Genomics 2014; 15:1076. [PMID: 25481572 PMCID: PMC4298942 DOI: 10.1186/1471-2164-15-1076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/24/2014] [Indexed: 11/19/2022] Open
Abstract
Background Maintenance of metal homeostasis is crucial in bacterial pathogenicity as metal starvation is the most important mechanism in the nutritional immunity strategy of host cells. Thus, pathogenic bacteria have evolved sensitive metal scavenging systems to overcome this particular host defence mechanism. The ruminant pathogen Mycobacterium avium ssp. paratuberculosis (MAP) displays a unique gut tropism and causes a chronic progressive intestinal inflammation. MAP possesses eight conserved lineage specific large sequence polymorphisms (LSP), which distinguish MAP from its ancestral M. avium ssp. hominissuis or other M. avium subspecies. LSP14 and LSP15 harbour many genes proposed to be involved in metal homeostasis and have been suggested to substitute for a MAP specific, impaired mycobactin synthesis. Results In the present study, we found that a LSP14 located putative IrtAB-like iron transporter encoded by mptABC was induced by zinc but not by iron starvation. Heterologous reporter gene assays with the lacZ gene under control of the mptABC promoter in M. smegmatis (MSMEG) and in a MSMEG∆furB deletion mutant revealed a zinc dependent, metalloregulator FurB mediated expression of mptABC via a conserved mycobacterial FurB recognition site. Deep sequencing of RNA from MAP cultures treated with the zinc chelator TPEN revealed that 70 genes responded to zinc limitation. Remarkably, 45 of these genes were located on a large genomic island of approximately 90 kb which harboured LSP14 and LSP15. Thirty-five of these genes were predicted to be controlled by FurB, due to the presence of putative binding sites. This clustering of zinc responsive genes was exclusively found in MAP and not in other mycobacteria. Conclusions Our data revealed a particular genomic signature for MAP given by a unique zinc specific locus, thereby suggesting an exceptional relevance of zinc for the metabolism of MAP. MAP seems to be well adapted to maintain zinc homeostasis which might contribute to the peculiarity of MAP pathogenicity. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1076) contains supplementary material, which is available to authorized users.
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17
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Rathnaiah G, Lamont EA, Harris NB, Fenton RJ, Zinniel DK, Liu X, Sotos J, Feng Z, Livneh-Kol A, Shpigel NY, Czuprynski CJ, Sreevatsan S, Barletta RG. Generation and screening of a comprehensive Mycobacterium avium subsp. paratuberculosis transposon mutant bank. Front Cell Infect Microbiol 2014; 4:144. [PMID: 25360421 PMCID: PMC4197770 DOI: 10.3389/fcimb.2014.00144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/25/2014] [Indexed: 01/10/2023] Open
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of Johne's Disease in ruminants. This enteritis has significant economic impact and worldwide distribution. Vaccination is one of the most cost effective infectious disease control measures. Unfortunately, current vaccines reduce clinical disease and shedding, but are of limited efficacy and do not provide long-term protective immunity. Several strategies have been followed to mine the MAP genome for virulence determinants that could be applied to vaccine and diagnostic assay development. In this study, a comprehensive mutant bank of 13,536 MAP K-10 Tn5367 mutants (P > 95%) was constructed and screened in vitro for phenotypes related to virulence. This strategy was designated to maximize identification of genes important to MAP pathogenesis without relying on studies of other mycobacterial species that may not translate into similar effects in MAP. This bank was screened for mutants with colony morphology alterations, susceptibility to D-cycloserine, impairment in siderophore production or secretion, reduced cell association, and decreased biofilm and clump formation. Mutants with interesting phenotypes were analyzed by PCR, Southern blotting and DNA sequencing to determine transposon insertion sites. These insertion sites mapped upstream from the MAP1152-MAP1156 cluster, internal to either the Mod operon gene MAP1566 or within the coding sequence of lsr2, and several intergenic regions. Growth curves in broth cultures, invasion assays and kinetics of survival and replication in primary bovine macrophages were also determined. The ability of vectors carrying Tn5370 to generate stable MAP mutants was also investigated.
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Affiliation(s)
- Govardhan Rathnaiah
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Elise A Lamont
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul MN, USA
| | - N Beth Harris
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Robert J Fenton
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Denise K Zinniel
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Xiaofei Liu
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Josh Sotos
- School of Veterinary Medicine, University of Wisconsin Madison, WI, USA
| | - Zhengyu Feng
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
| | - Ayala Livneh-Kol
- The Koret School of Veterinary Medicine, The Hebrew University of Jerusalem Rehovot, Israel
| | - Nahum Y Shpigel
- The Koret School of Veterinary Medicine, The Hebrew University of Jerusalem Rehovot, Israel
| | | | - Srinand Sreevatsan
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul MN, USA
| | - Raúl G Barletta
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska Lincoln, NE, USA
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