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Behrmann LV, Meier K, Vollmer J, Chiedu CC, Schiefer A, Hoerauf A, Pfarr K. In vitro extracellular replication of Wolbachia endobacteria. Front Microbiol 2024; 15:1405287. [PMID: 39091298 PMCID: PMC11293327 DOI: 10.3389/fmicb.2024.1405287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024] Open
Abstract
Obligate intracellular endobacteria of the genus Wolbachia are widespread in arthropods and several filarial nematodes. Control programs for vector-borne diseases (dengue, Zika, malaria) and anti-filarial therapy with antibiotics are based on this important endosymbiont. Investigating Wolbachia, however, is impeded by the need for host cells. In this study, the requirements for Wolbachia wAlbB growth in a host cell-free in vitro culture system were characterized via qPCRs. A cell lysate fraction from Aedes albopictus C6/36 insect cells containing cell membranes and medium with fetal bovine serum were identified as requisite for cell-free replication of Wolbachia. Supplementation with the membrane fraction of insect cell lysate increased extracellular Wolbachia replication by 4.2-fold. Replication rates in the insect cell-free culture were lower compared to Wolbachia grown inside insect cells. However, the endobacteria were able to replicate for up to 12 days and to infect uninfected C6/36 cells. Cell-free Wolbachia treated with the lipid II biosynthesis inhibitor fosfomycin had an enlarged phenotype, seen previously for intracellular Wolbachia in C6/36 cells, indicating that the bacteria were unable to divide. In conclusion, we have developed a cell-free culture system in which Wolbachia replicate for up to 12 days, providing an in vitro tool to elucidate the biology of these endobacteria, e.g., cell division by using compounds that may not enter the C6/36 cells. A better understanding of Wolbachia biology, and in particular host-symbiont interactions, is key to the use of Wolbachia in vector control programs and to future drug development against filarial diseases.
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Affiliation(s)
- Lara Vanessa Behrmann
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Kirstin Meier
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Jennifer Vollmer
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Chukwuebuka Chibuzo Chiedu
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Andrea Schiefer
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Kenneth Pfarr
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
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2
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Mandel CG, Sanchez SE, Monahan CC, Phuklia W, Omsland A. Metabolism and physiology of pathogenic bacterial obligate intracellular parasites. Front Cell Infect Microbiol 2024; 14:1284701. [PMID: 38585652 PMCID: PMC10995303 DOI: 10.3389/fcimb.2024.1284701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 02/01/2024] [Indexed: 04/09/2024] Open
Abstract
Bacterial obligate intracellular parasites (BOIPs) represent an exclusive group of bacterial pathogens that all depend on invasion of a eukaryotic host cell to reproduce. BOIPs are characterized by extensive adaptation to their respective replication niches, regardless of whether they replicate within the host cell cytoplasm or within specialized replication vacuoles. Genome reduction is also a hallmark of BOIPs that likely reflects streamlining of metabolic processes to reduce the need for de novo biosynthesis of energetically costly metabolic intermediates. Despite shared characteristics in lifestyle, BOIPs show considerable diversity in nutrient requirements, metabolic capabilities, and general physiology. In this review, we compare metabolic and physiological processes of prominent pathogenic BOIPs with special emphasis on carbon, energy, and amino acid metabolism. Recent advances are discussed in the context of historical views and opportunities for discovery.
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Affiliation(s)
- Cameron G. Mandel
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Savannah E. Sanchez
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
| | - Colleen C. Monahan
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Weerawat Phuklia
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People’s Democratic Republic
| | - Anders Omsland
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
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3
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Schulze-Luehrmann J, Liebler-Tenorio E, Felipe-López A, Lührmann A. Cell death induction facilitates egress of Coxiella burnetii from infected host cells at late stages of infection. Mol Microbiol 2024; 121:513-528. [PMID: 38115201 DOI: 10.1111/mmi.15210] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/21/2023]
Abstract
Intracellular bacteria have evolved mechanisms to invade host cells, establish an intracellular niche that allows survival and replication, produce progeny, and exit the host cell after completion of the replication cycle to infect new target cells. Bacteria exit their host cell by (i) initiation of apoptosis, (ii) lytic cell death, and (iii) exocytosis. While bacterial egress is essential for bacterial spreading and, thus, pathogenesis, we currently lack information about egress mechanisms for the obligate intracellular pathogen C. burnetii, the causative agent of the zoonosis Q fever. Here, we demonstrate that C. burnetii inhibits host cell apoptosis early during infection, but induces and/or increases apoptosis at later stages of infection. Only at later stages of infection did we observe C. burnetii egress, which depends on previously established large bacteria-filled vacuoles and a functional intrinsic apoptotic cascade. The released bacteria are not enclosed by a host cell membrane and can infect and replicate in new target cells. In summary, our data argue that C. burnetii egress in a non-synchronous way at late stages of infection. Apoptosis-induction is important for C. burnetii egress, but other pathways most likely contribute.
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Affiliation(s)
- Jan Schulze-Luehrmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Alfonso Felipe-López
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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4
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Clemente TM, Angara RK, Gilk SD. Establishing the intracellular niche of obligate intracellular vacuolar pathogens. Front Cell Infect Microbiol 2023; 13:1206037. [PMID: 37645379 PMCID: PMC10461009 DOI: 10.3389/fcimb.2023.1206037] [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: 04/14/2023] [Accepted: 07/21/2023] [Indexed: 08/31/2023] Open
Abstract
Obligate intracellular pathogens occupy one of two niches - free in the host cell cytoplasm or confined in a membrane-bound vacuole. Pathogens occupying membrane-bound vacuoles are sequestered from the innate immune system and have an extra layer of protection from antimicrobial drugs. However, this lifestyle presents several challenges. First, the bacteria must obtain membrane or membrane components to support vacuole expansion and provide space for the increasing bacteria numbers during the log phase of replication. Second, the vacuole microenvironment must be suitable for the unique metabolic needs of the pathogen. Third, as most obligate intracellular bacterial pathogens have undergone genomic reduction and are not capable of full metabolic independence, the bacteria must have mechanisms to obtain essential nutrients and resources from the host cell. Finally, because they are separated from the host cell by the vacuole membrane, the bacteria must possess mechanisms to manipulate the host cell, typically through a specialized secretion system which crosses the vacuole membrane. While there are common themes, each bacterial pathogen utilizes unique approach to establishing and maintaining their intracellular niches. In this review, we focus on the vacuole-bound intracellular niches of Anaplasma phagocytophilum, Ehrlichia chaffeensis, Chlamydia trachomatis, and Coxiella burnetii.
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Affiliation(s)
| | | | - Stacey D. Gilk
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, United States
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5
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Anderson MW, Binette P, Richards C, Beare PA, Heinzen RA, Long CM. A simple method for enrichment of phase I Coxiella burnetii. J Microbiol Methods 2023; 211:106787. [PMID: 37453478 PMCID: PMC10529119 DOI: 10.1016/j.mimet.2023.106787] [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: 05/09/2023] [Revised: 06/16/2023] [Accepted: 07/12/2023] [Indexed: 07/18/2023]
Abstract
Coxiella burnetii is the bacterial causative agent of the zoonosis Q fever. This bacterium undergoes lipopolysaccharide (LPS) phase transition similar to Enterobacteriaciae upon in vitro passage. Full-length, phase I C. burnetii LPS is a critical virulence factor and profoundly impacts vaccine-induced immunogenicity; thus, LPS phase is an important consideration in C. burnetii experimentation and Q fever vaccine design. Typically, phase I LPS-expressing organisms are obtained from the tissues of infected experimental animals. In this process, residual phase II LPS-expressing organisms are thought to be cleared by the host immune system. Here, we propose an efficient and non-animal-based method for the enrichment of C. burnetii phase I LPS-expressing bacteria in vitro. We utilize both Vero cell culture to selectively enrich solutions with phase I and intermediate phase LPS-expressing bacteria. This simple and quick method decreases reliance on experimental animals and is a sustainable solution for Q fever diagnostic and vaccine development hurdles.
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Affiliation(s)
- Matthew W Anderson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Picabo Binette
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Crystal Richards
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Carrie M Long
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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6
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Fisher DJ, Beare PA. Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria. Front Cell Infect Microbiol 2023; 13:1202245. [PMID: 37404720 PMCID: PMC10315504 DOI: 10.3389/fcimb.2023.1202245] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/06/2023] Open
Abstract
The ability to genetically manipulate a pathogen is fundamental to discovering factors governing host-pathogen interactions at the molecular level and is critical for devising treatment and prevention strategies. While the genetic "toolbox" for many important bacterial pathogens is extensive, approaches for modifying obligate intracellular bacterial pathogens were classically limited due in part to the uniqueness of their obligatory lifestyles. Many researchers have confronted these challenges over the past two and a half decades leading to the development of multiple approaches to construct plasmid-bearing recombinant strains and chromosomal gene inactivation and deletion mutants, along with gene-silencing methods enabling the study of essential genes. This review will highlight seminal genetic achievements and recent developments (past 5 years) for Anaplasma spp., Rickettsia spp., Chlamydia spp., and Coxiella burnetii including progress being made for the still intractable Orientia tsutsugamushi. Alongside commentary of the strengths and weaknesses of the various approaches, future research directions will be discussed to include methods for C. burnetii that should have utility in the other obligate intracellular bacteria. Collectively, the future appears bright for unraveling the molecular pathogenic mechanisms of these significant pathogens.
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Affiliation(s)
- Derek J. Fisher
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Paul A. Beare
- Rocky Mountain Laboratory, National Institute of Health, Hamilton, MT, United States
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7
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Riffaud CM, Rucks EA, Ouellette SP. Persistence of obligate intracellular pathogens: alternative strategies to overcome host-specific stresses. Front Cell Infect Microbiol 2023; 13:1185571. [PMID: 37284502 PMCID: PMC10239878 DOI: 10.3389/fcimb.2023.1185571] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/05/2023] [Indexed: 06/08/2023] Open
Abstract
In adapting to the intracellular niche, obligate intracellular bacteria usually undergo a reduction of genome size by eliminating genes not needed for intracellular survival. These losses can include, for example, genes involved in nutrient anabolic pathways or in stress response. Living inside a host cell offers a stable environment where intracellular bacteria can limit their exposure to extracellular effectors of the immune system and modulate or outright inhibit intracellular defense mechanisms. However, highlighting an area of vulnerability, these pathogens are dependent on the host cell for nutrients and are very sensitive to conditions that limit nutrient availability. Persistence is a common response shared by evolutionarily divergent bacteria to survive adverse conditions like nutrient deprivation. Development of persistence usually compromises successful antibiotic therapy of bacterial infections and is associated with chronic infections and long-term sequelae for the patients. During persistence, obligate intracellular pathogens are viable but not growing inside their host cell. They can survive for a long period of time such that, when the inducing stress is removed, reactivation of their growth cycles resumes. Given their reduced coding capacity, intracellular bacteria have adapted different response mechanisms. This review gives an overview of the strategies used by the obligate intracellular bacteria, where known, which, unlike model organisms such as E. coli, often lack toxin-antitoxin systems and the stringent response that have been linked to a persister phenotype and amino acid starvation states, respectively.
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8
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Yadav A, Brewer MN, Elshahed MS, Shaw EI. Comparative Transcriptomics and Genomics from Continuous Axenic Media Growth Identifies Coxiella burnetii Intracellular Survival Strategies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527305. [PMID: 36798183 PMCID: PMC9934583 DOI: 10.1101/2023.02.06.527305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Coxiella burnetii (Cb) is an obligate intracellular pathogen in nature and the causative agent of acute Q fever as well as chronic diseases. In an effort to identify genes and proteins crucial to their normal intracellular growth lifestyle, we applied a "Reverse evolution" approach where the avirulent Nine Mile Phase II strain of Cb was grown for 67 passages in chemically defined ACCM-D media and gene expression patterns and genome integrity from various passages was compared to passage number one following intracellular growth. Transcriptomic analysis identified a marked downregulation of the structural components of the type 4B secretion system (T4BSS), the general secretory (sec) pathway, as well as 14 out of 118 previously identified genes encoding effector proteins. Additional downregulated pathogenicity determinants genes included several chaperones, LPS, and peptidoglycan biosynthesis. A general marked downregulation of central metabolic pathways was also observed, which was balanced by a marked upregulation of genes encoding transporters. This pattern reflected the richness of the media and diminishing anabolic and ATP-generation needs. Finally, genomic sequencing and comparative genomic analysis demonstrated an extremely low level of mutation across passages, despite the observed Cb gene expression changes following acclimation to axenic media.
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Affiliation(s)
- Archana Yadav
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
| | - Melissa N. Brewer
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
- Biological Sciences. Southeastern Oklahoma State University. Durant, OK. USA
| | - Mostafa S. Elshahed
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
| | - Edward I. Shaw
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
- Department of Biomedical Sciences. Philadelphia College of Osteopathic Medicine. Moultrie, GA. USA
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9
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MicroRNAs Contribute to Host Response to Coxiella burnetii. Infect Immun 2023; 91:e0019922. [PMID: 36537791 PMCID: PMC9872603 DOI: 10.1128/iai.00199-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
MicroRNAs (miRNAs), a class of small noncoding RNAs, are critical to gene regulation in eukaryotes. They are involved in modulating a variety of physiological processes, including the host response to intracellular infections. Little is known about miRNA functions during infection by Coxiella burnetii, the causative agent of human Q fever. This bacterial pathogen establishes a large replicative vacuole within macrophages by manipulating host processes such as apoptosis and autophagy. We investigated miRNA expression in C. burnetii-infected macrophages and identified several miRNAs that were down- or upregulated during infection. We further explored the functions of miR-143-3p, an miRNA whose expression is downregulated in macrophages infected with C. burnetii, and show that increasing the abundance of this miRNA in human cells results in increased apoptosis and reduced autophagy-conditions that are unfavorable to C. burnetii intracellular growth. In sum, this study demonstrates that C. burnetii infection elicits a robust miRNA-based host response, and because miR-143-3p promotes apoptosis and inhibits autophagy, downregulation of miR-143-3p expression during C. burnetii infection likely benefits the pathogen.
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10
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Yadav A, Brewer MN, Elshahed MS, Shaw EI. Comparative transcriptomics and genomics from continuous axenic media growth identifies Coxiella burnetii intracellular survival strategies. Pathog Dis 2023; 81:ftad009. [PMID: 37193663 PMCID: PMC10237335 DOI: 10.1093/femspd/ftad009] [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: 02/06/2023] [Revised: 04/17/2023] [Accepted: 05/15/2023] [Indexed: 05/18/2023] Open
Abstract
Coxiella burnetii (Cb) is an obligate intracellular pathogen in nature and the causative agent of acute Q fever as well as chronic diseases. In an effort to identify genes and proteins crucial to their normal intracellular growth lifestyle, we applied a 'reverse evolution' approach where the avirulent Nine Mile Phase II strain of Cb was grown for 67 passages in chemically defined ACCM-D media and gene expression patterns and genome integrity from various passages was compared to passage number one following intracellular growth. Transcriptomic analysis identified a marked downregulation of the structural components of the type 4B secretion system (T4BSS), the general secretory (Sec) pathway, as well as 14 out of 118 previously identified genes encoding effector proteins. Additional downregulated pathogenicity determinants genes included several chaperones, LPS, and peptidoglycan biosynthesis. A general marked downregulation of central metabolic pathways was also observed, which was balanced by a marked upregulation of genes encoding transporters. This pattern reflected the richness of the media and diminishing anabolic, and ATP-generation needs. Finally, genomic sequencing and comparative genomic analysis demonstrated an extremely low level of mutation across passages, despite the observed Cb gene expression changes following acclimation to axenic media.
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Affiliation(s)
- Archana Yadav
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
| | - Melissa N Brewer
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
- Biological Sciences, Southeastern Oklahoma State University, 74078 Durant, OK, United States
| | - Mostafa S Elshahed
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
| | - Edward I Shaw
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, 74078 Moultrie, GA, United States
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11
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Kohl L, Siddique MNAA, Bodendorfer B, Berger R, Preikschat A, Daniel C, Ölke M, Liebler‐Tenorio E, Schulze‐Luehrmann J, Mauermeir M, Yang K, Hayek I, Szperlinski M, Andrack J, Schleicher U, Bozec A, Krönke G, Murray PJ, Wirtz S, Yamamoto M, Schatz V, Jantsch J, Oefner P, Degrandi D, Pfeffer K, Mertens‐Scholz K, Rauber S, Bogdan C, Dettmer K, Lührmann A, Lang R. Macrophages inhibit Coxiella burnetii by the ACOD1-itaconate pathway for containment of Q fever. EMBO Mol Med 2022; 15:e15931. [PMID: 36479617 PMCID: PMC9906395 DOI: 10.15252/emmm.202215931] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 11/19/2022] [Accepted: 11/22/2022] [Indexed: 12/12/2022] Open
Abstract
Infection with the intracellular bacterium Coxiella (C.) burnetii can cause chronic Q fever with severe complications and limited treatment options. Here, we identify the enzyme cis-aconitate decarboxylase 1 (ACOD1 or IRG1) and its product itaconate as protective host immune pathway in Q fever. Infection of mice with C. burnetii induced expression of several anti-microbial candidate genes, including Acod1. In macrophages, Acod1 was essential for restricting C. burnetii replication, while other antimicrobial pathways were dispensable. Intratracheal or intraperitoneal infection of Acod1-/- mice caused increased C. burnetii burden, weight loss and stronger inflammatory gene expression. Exogenously added itaconate restored pathogen control in Acod1-/- mouse macrophages and blocked replication in human macrophages. In axenic cultures, itaconate directly inhibited growth of C. burnetii. Finally, treatment of infected Acod1-/- mice with itaconate efficiently reduced the tissue pathogen load. Thus, ACOD1-derived itaconate is a key factor in the macrophage-mediated defense against C. burnetii and may be exploited for novel therapeutic approaches in chronic Q fever.
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Affiliation(s)
- Lisa Kohl
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Md Nur A Alam Siddique
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Barbara Bodendorfer
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Raffaela Berger
- Institute of Functional GenomicsUniversity of RegensburgRegensburgGermany
| | - Annica Preikschat
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Christoph Daniel
- Department of NephropathologyUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
| | - Martha Ölke
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Elisabeth Liebler‐Tenorio
- Institute of Molecular Pathogenesis, Friedrich‐Loeffler‐Institut, Federal Research Institute for Animal HealthJenaGermany
| | - Jan Schulze‐Luehrmann
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Michael Mauermeir
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Kai‐Ting Yang
- Department of Medicine 3Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany,Deutsches Zentrum für Immuntherapie (DZI)Friedrich‐Alexander‐Universität Erlangen‐Nürnberg and Universitätsklinikum ErlangenErlangenGermany
| | - Inaya Hayek
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Manuela Szperlinski
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany
| | - Jennifer Andrack
- Institute of Bacterial Infections and Zoonoses, Friedrich‐Loeffler‐Institut, Federal Research Institute for Animal HealthJenaGermany
| | - Ulrike Schleicher
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
| | - Aline Bozec
- Department of Medicine 3Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
| | - Gerhard Krönke
- Department of Medicine 3Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
| | | | - Stefan Wirtz
- Deutsches Zentrum für Immuntherapie (DZI)Friedrich‐Alexander‐Universität Erlangen‐Nürnberg and Universitätsklinikum ErlangenErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany,Department of Medicine 1Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
| | | | - Valentin Schatz
- Institute of Clinical MicrobiologyUniversity Hospital RegensburgRegensburgGermany
| | - Jonathan Jantsch
- Institute of Clinical MicrobiologyUniversity Hospital RegensburgRegensburgGermany,Present address:
Institute for Medical Microbiology, Immunology and HygieneUniversity Hospital Cologne and Faculty of Medicine, University of CologneCologneGermany
| | - Peter Oefner
- Institute of Functional GenomicsUniversity of RegensburgRegensburgGermany
| | - Daniel Degrandi
- Institute of Medical MicrobiologyHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Klaus Pfeffer
- Institute of Medical MicrobiologyHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Katja Mertens‐Scholz
- Institute of Bacterial Infections and Zoonoses, Friedrich‐Loeffler‐Institut, Federal Research Institute for Animal HealthJenaGermany
| | - Simon Rauber
- Department of Medicine 3Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany,Deutsches Zentrum für Immuntherapie (DZI)Friedrich‐Alexander‐Universität Erlangen‐Nürnberg and Universitätsklinikum ErlangenErlangenGermany
| | - Christian Bogdan
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
| | - Katja Dettmer
- Institute of Functional GenomicsUniversity of RegensburgRegensburgGermany
| | - Anja Lührmann
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
| | - Roland Lang
- Mikrobiologisches Institut – Klinische Mikrobiologie, Immunologie und HygieneUniversitätsklinikum Erlangen, Friedrich‐Alexander‐Universität (FAU) Erlangen‐NürnbergErlangenGermany,Medical Immunology Campus ErlangenFAU Erlangen‐NürnbergErlangenGermany
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12
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Wachter S, Cockrell DC, Miller HE, Virtaneva K, Kanakabandi K, Darwitz B, Heinzen RA, Beare PA. The endogenous Coxiella burnetii plasmid encodes a functional toxin-antitoxin system. Mol Microbiol 2022; 118:744-764. [PMID: 36385554 PMCID: PMC10098735 DOI: 10.1111/mmi.15001] [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: 09/23/2022] [Revised: 10/25/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022]
Abstract
Coxiella burnetii is the causative agent of Q fever. All C. burnetii isolates encode either an autonomously replicating plasmid (QpH1, QpDG, QpRS, or QpDV) or QpRS-like chromosomally integrated plasmid sequences. The role of the ORFs present in these sequences is unknown. Here, the role of the ORFs encoded on QpH1 was investigated. Using a new C. burnetii shuttle vector (pB-TyrB-QpH1ori), we cured the C. burnetii Nine Mile Phase II strain of QpH1. The ΔQpH1 strain grew normally in axenic media but had a significant growth defect in Vero cells, indicating QpH1 was important for C. burnetii virulence. We developed an inducible CRISPR interference system to examine the role of individual QpH1 plasmid genes. CRISPRi of cbuA0027 resulted in significant growth defects in axenic media and THP-1 cells. The cbuA0028/cbuA0027 operon encodes CBUA0028 (ToxP) and CBUA0027 (AntitoxP), which are homologous to the HigB2 toxin and HigA2 antitoxin, respectively, from Vibrio cholerae. Consistent with toxin-antitoxin systems, overexpression of toxP resulted in a severe intracellular growth defect that was rescued by co-expression of antitoxP. ToxP inhibited protein translation. AntitoxP bound the toxP promoter (PtoxP) and ToxP, with the resulting complex binding also PtoxP. In summary, our data indicate that C. burnetii maintains an autonomously replicating plasmid because of a plasmid-based toxin-antitoxin system.
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Affiliation(s)
- Shaun Wachter
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada
| | - Diane C Cockrell
- Vector-Pathogen-Host Interaction unit, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | | | - Kimmo Virtaneva
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Kishore Kanakabandi
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Benjamin Darwitz
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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13
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Tesfamariam M, Binette P, Cockrell D, Beare PA, Heinzen RA, Shaia C, Long CM. Characterization of Coxiella burnetii Dugway Strain Host-Pathogen Interactions In Vivo. Microorganisms 2022; 10:2261. [PMID: 36422331 PMCID: PMC9692954 DOI: 10.3390/microorganisms10112261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 12/12/2023] Open
Abstract
Coxiella burnetii is a Gram-negative, intracellular bacterium that causes the zoonosis Q fever. Among the many natural isolates of C. burnetii recovered from various sources, the Dugway group exhibits unique genetic characteristics, including the largest C. burnetii genomes. These strains were isolated during 1954-1958 from wild rodents from the Utah, USA desert. Despite retaining phase I lipopolysaccharide and the type 4B secretion system, two critical virulence factors, avirulence has been reported in a guinea pig infection model. Using guinea pig models, we evaluated the virulence, whole-cell vaccine (WCV) efficacy, and post-vaccination hypersensitivity (PVH) potential of a representative Dugway strain. Consistent with prior reports, Dugway appeared to be highly attenuated compared to a virulent strain. Indeed, Dugway-infected animals showed similarly low levels of fever, body weight loss, and splenomegaly like Nine Mile II-infected animals. When compared to a human Q fever vaccine, QVax®, Dugway WCV exhibited analogous protection against a heterologous Nine Mile I challenge. PVH was investigated in a skin-testing model which revealed significantly decreased maximum erythema in Dugway Δdot/icm WCV-skin-tested animals compared to that of QVax®. These data provide insight into this unique bacterial strain and implicate its potential use as a mutated WCV candidate.
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Affiliation(s)
- Mahelat Tesfamariam
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Picabo Binette
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Diane Cockrell
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Paul A. Beare
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Robert A. Heinzen
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Carl Shaia
- Rocky Mountain Veterinary Branch, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
| | - Carrie Mae Long
- Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT 59840, USA
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14
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Ölander M, Sixt BS. Bringing genetics to heretofore intractable obligate intracellular bacterial pathogens: Chlamydia and beyond. PLoS Pathog 2022; 18:e1010669. [PMID: 35901011 PMCID: PMC9333220 DOI: 10.1371/journal.ppat.1010669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Magnus Ölander
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Barbara S. Sixt
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
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15
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Binette P, Tesfamariam M, Cockrell D, Heinzen RA, Richards C, Shaia C, Long CM. Murine Q Fever Vaccination Model Reveals Sex Dimorphism in Early Phase Delayed-Type Hypersensitivity Responses. Front Immunol 2022; 13:894536. [PMID: 35784317 PMCID: PMC9241443 DOI: 10.3389/fimmu.2022.894536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/13/2022] [Indexed: 11/26/2022] Open
Abstract
Delayed-type hypersensitivity (DTH) responses to microbial vaccines and related components are a major roadblock for widespread licensing of whole cell vaccines such as that of Q fever. Q fever is a zoonotic disease caused by the intracellular bacterium Coxiella burnetii. The only currently licensed vaccine, Q-Vax®, is a whole cell inactivated formulation that is associated with a potentially severe dermal post vaccination DTH response in previously sensitized individuals. To investigate the underlying immunologic mechanisms of this response and better represent the early-phase DTH response observed in humans, a murine sensitization and skin testing model was developed and employed. Female C57Bl/6J mice displayed the most robust early-phase DTH responses following sensitization and elicitation compared to their male counterparts and other mouse strains. Immunologic responses were measured within the skin, draining lymph nodes, and serum following both sensitization and elicitation with Q fever whole cell vaccines. Local immunologic responses in the dermis were characterized by inflammation primarily involving neutrophils, macrophages, and T cells. Secondary lymphoid organ profiling revealed distinct immunological signatures following both sensitization and elicitation with a sex-based dichotomy in T cell phenotypes and antigen presenting cell numbers. Beyond providing a post-Q fever vaccination DTH model that recapitulates early-phase DTH events, these data suggest that sex is a primary factor influencing the magnitude and composition of the ensuing response.
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Affiliation(s)
- Picabo Binette
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Mahelat Tesfamariam
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Diane Cockrell
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Robert A. Heinzen
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Crystal Richards
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Carl Shaia
- Rocky Mountain Veterinary Branch, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
| | - Carrie Mae Long
- Laboratory of Bacteriology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Hamilton, MT, United States
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16
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Coxiella burnetii Plasmid Effector B Promotes LC3-II Accumulation and Contributes To Bacterial Virulence in a SCID Mouse Model. Infect Immun 2022; 90:e0001622. [PMID: 35587202 DOI: 10.1128/iai.00016-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Coxiella burnetii, the causative agent of zoonotic Q fever, is characterized by replicating inside the lysosome-derived Coxiella-containing vacuole (CCV) in host cells. Some effector proteins secreted by C. burnetii have been reported to be involved in the manipulation of autophagy to facilitate the development of CCVs and bacterial replication. Here, we found that the Coxiella plasmid effector B (CpeB) localizes on vacuole membrane targeted by LC3 and LAMP1 and promotes LC3-II accumulation. Meanwhile, the C. burnetii strain lacking the QpH1 plasmid induced less LC3-II accumulation, which was accompanied by smaller CCVs and lower bacterial loads in THP-1 cells. Expression of CpeB in the strain lacking QpH1 led to restoration in LC3-II accumulation but had no effect on the smaller CCV phenotype. In the severe combined immune deficiency (SCID) mouse model, infections with the strain expressing CpeB led to significantly higher bacterial burdens in the spleen and liver than its parent strain devoid of QpH1. We also found that CpeB targets Rab11a to promote LC3-II accumulation. Intratracheally inoculated C. burnetii resulted in lower bacterial burdens and milder lung lesions in Rab11a conditional knockout (Rab11a-/- CKO) mice. Collectively, these results suggest that CpeB promotes C. burnetii virulence by inducing LC3-II accumulation via a pathway involving Rab11a.
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17
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Cordsmeier A, Rinkel S, Jeninga M, Schulze-Luehrmann J, Ölke M, Schmid B, Hasler D, Meister G, Häcker G, Petter M, Beare PA, Lührmann A. The Coxiella burnetii T4SS effector protein AnkG hijacks the 7SK small nuclear ribonucleoprotein complex for reprogramming host cell transcription. PLoS Pathog 2022; 18:e1010266. [PMID: 35134097 PMCID: PMC8824381 DOI: 10.1371/journal.ppat.1010266] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 01/10/2022] [Indexed: 11/24/2022] Open
Abstract
Inhibition of host cell apoptosis is crucial for survival and replication of several intracellular bacterial pathogens. To interfere with apoptotic pathways, some pathogens use specialized secretion systems to inject bacterial effector proteins into the host cell cytosol. One of these pathogens is the obligate intracellular bacterium Coxiella burnetii, the etiological agent of the zoonotic disease Q fever. In this study, we analyzed the molecular activity of the anti-apoptotic T4SS effector protein AnkG (CBU0781) to understand how C. burnetii manipulates host cell viability. We demonstrate by co- and RNA-immunoprecipitation that AnkG binds to the host cell DExD box RNA helicase 21 (DDX21) as well as to the host cell 7SK small nuclear ribonucleoprotein (7SK snRNP) complex, an important regulator of the positive transcription elongation factor b (P-TEFb). The co-immunoprecipitation of AnkG with DDX21 is probably mediated by salt bridges and is independent of AnkG-7SK snRNP binding, and vice versa. It is known that DDX21 facilitates the release of P-TEFb from the 7SK snRNP complex. Consistent with the documented function of released P-TEFb in RNA Pol II pause release, RNA sequencing experiments confirmed AnkG-mediated transcriptional reprogramming and showed that expression of genes involved in apoptosis, trafficking, and transcription are influenced by AnkG. Importantly, DDX21 and P-TEFb are both essential for AnkG-mediated inhibition of host cell apoptosis, emphasizing the significance of the interaction of AnkG with both, the DDX21 protein and the 7SK RNA. In line with a critical function of AnkG in pathogenesis, the AnkG deletion C. burnetii strain was severely affected in its ability to inhibit host cell apoptosis and to generate a replicative C. burnetii-containing vacuole. In conclusion, the interference with the activity of regulatory host cell RNAs mediated by a bacterial effector protein represent a novel mechanism through which C. burnetii modulates host cell transcription, thereby enhancing permissiveness to bacterial infection. For intracellular replication, Coxiella burnetii depends on a functional type IV secretion system, which is utilized to inject ~150 virulence factors, so called effector proteins, into the host cell cytosol. Activities have only been established for few of them. These effector proteins interfere with vesicular trafficking, autophagy, lipid metabolism, apoptosis, and transcription by binding and manipulating the activity of host cell proteins. Here, we report that the C. burnetii T4SS effector protein AnkG (CBU0781, Q83DF6) binds to the host cell DExD box helicase 21 (DDX21) as well as to several host cell RNAs, including the small regulatory 7SK RNA, which is an important regulator of the positive elongation factor b (pTEFb). AnkG interferes with the function of the 7SK small nuclear ribonucleoprotein (7SK snRNP) complex, leading to significant changes in host cell transcription and ensuring host cell survival. AnkG activity is essential for efficient intracellular replication of C. burnetii and its ability to inhibit apoptosis. In summary, we identified a novel process by which a bacterial effector protein manipulates the host cell for its own benefit.
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Affiliation(s)
- Arne Cordsmeier
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sven Rinkel
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Myriam Jeninga
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martha Ölke
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Benedikt Schmid
- Lehrstuhl für Biotechnik, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Daniele Hasler
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Gunter Meister
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Georg Häcker
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center-University of Freiburg, Freiburg, Germany
| | - Michaela Petter
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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18
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Zhang Y, Fu J, Liu S, Wang L, Qiu J, van Schaik EJ, Samuel JE, Song L, Luo ZQ. Coxiella burnetii inhibits host immunity by a protein phosphatase adapted from glycolysis. Proc Natl Acad Sci U S A 2022; 119:e2110877119. [PMID: 34930823 PMCID: PMC8740755 DOI: 10.1073/pnas.2110877119] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 11/30/2022] Open
Abstract
Coxiella burnetii is a bacterial pathogen that replicates within host cells by establishing a membrane-bound niche called the Coxiella-containing vacuole. Biogenesis of this compartment requires effectors of its Dot/Icm type IV secretion system. A large cohort of such effectors has been identified, but the function of most of them remain elusive. Here, by a cell-based functional screening, we identified the effector Cbu0513 (designated as CinF) as an inhibitor of NF-κB signaling. CinF is highly similar to a fructose-1,6-bisphosphate (FBP) aldolase/phosphatase present in diverse bacteria. Further study reveals that unlike its ortholog from Sulfolobus tokodaii, CinF does not exhibit FBP phosphatase activity. Instead, it functions as a protein phosphatase that specifically dephosphorylates and stabilizes IκBα. The IκBα phosphatase activity is essential for the role of CinF in C. burnetii virulence. Our results establish that C. burnetii utilizes a protein adapted from sugar metabolism to subvert host immunity.
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Affiliation(s)
- Yong Zhang
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Zoonotic Diseases, The First Hospital of Jilin University, Changchun 130021, China
| | - Jiaqi Fu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Shuxin Liu
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Zoonotic Diseases, The First Hospital of Jilin University, Changchun 130021, China
| | - Lidong Wang
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Zoonotic Diseases, The First Hospital of Jilin University, Changchun 130021, China
| | - Jiazhang Qiu
- State Key Laboratory for Zoonotic Diseases, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Erin J van Schaik
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Bryan, TX 77807
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Bryan, TX 77807
| | - Lei Song
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Zoonotic Diseases, The First Hospital of Jilin University, Changchun 130021, China;
| | - Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907;
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19
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Kumaresan V, Alam S, Zhang Y, Zhang G. The Feasibility of Using Coxiella burnetii Avirulent Nine Mile Phase II Viable Bacteria as a Live Attenuated Vaccine Against Q fever. Front Immunol 2021; 12:754690. [PMID: 34795669 PMCID: PMC8594375 DOI: 10.3389/fimmu.2021.754690] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/04/2021] [Indexed: 11/13/2022] Open
Abstract
This study aimed to explore if viable C. burnetii avirulent Nine Mile phase II (NMII) can elicit protective immunity against virulent NM phase I (NMI) infection. Interestingly, mice immunized with viable NMII elicited significant protection against NMI infection at different time points post-immunization. Viable NMII induced a dose-dependent NMI-specific IgG response in mice, but all doses of NMII-immunized mice conferred a similar level of protection. Comparing different routes of immunization indicated that intranasally immunized mice showed significantly higher levels of protection than other immunization routes. The observation that viable NMII induced a similar level of long-term protection against NMI challenge as the formalin-inactivated NMI vaccine (PIV) suggests that viable NMII bacteria can induce a similar level of long-term protection against virulent NMI challenge as the PIV. Viable NMII also induced significant protection against challenge with virulent Priscilla and Scurry strains, suggesting that viable NMII can elicit broad protection. Immune sera and splenocytes from viable NMII-immunized mice are protective against NMI infection, but immune serum-receiving mice did not control NMI replication. Additionally, viable NMII conferred a comparable level of protection in wild-type, CD4+ T cell-deficient, and CD8+ T cell-deficient mice, and partial protection in B cell-deficient mice. However, NMII-immunized T cell-deficient mice were unable to prevent C. burnetii replication. Thus, both B cells and T cells are required for viable NMII-induced protective immunity but T cells may play a critical role. Collectively, this study demonstrates the feasibility of using avirulent NMII as a live attenuated vaccine against human Q fever.
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Affiliation(s)
- Venkatesh Kumaresan
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Shawkat Alam
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Yan Zhang
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Guoquan Zhang
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
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20
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Abstract
Coxiella burnetii, the causative agent of query (Q) fever in humans, is an obligate intracellular bacterium. C. burnetii can naturally infect a broad range of host organisms (e.g., mammals and arthropods) and cell types. This amphotropic nature of C. burnetii, in combination with its ability to utilize both glycolytic and gluconeogenic carbon sources, suggests that the pathogen relies on metabolic plasticity to replicate in nutritionally diverse intracellular environments. To test the significance of metabolic plasticity in C. burnetii host cell colonization, C. burnetii intracellular replication in seven distinct cell lines was compared between a metabolically competent parental strain and a mutant, CbΔpckA, unable to undergo gluconeogenesis. Both the parental strain and CbΔpckA mutant exhibited host cell-dependent infection phenotypes, which were influenced by alterations to host glycolytic or gluconeogenic substrate availability. Because the nutritional environment directly impacts host cell physiology, our analysis was extended to investigate the response of C. burnetii replication in mammalian host cells cultivated in a novel physiological medium based on the nutrient composition of mammalian interstitial fluid, interstitial fluid-modeled medium (IFmM). An infection model based on IFmM resulted in exacerbation of a replication defect exhibited by the CbΔpckA mutant in specific cell lines. The CbΔpckA mutant was also attenuated during infection of an animal host. Overall, the study underscores that gluconeogenic capacity aids C. burnetii amphotropism and that the amphotropic nature of C. burnetii should be considered when resolving virulence mechanisms in this pathogen.
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21
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Ortiz-Severín J, Stuardo CJ, Jiménez NE, Palma R, Cortés MP, Maldonado J, Maass A, Cambiazo V. Nutrient Scarcity in a New Defined Medium Reveals Metabolic Resistance to Antibiotics in the Fish Pathogen Piscirickettsia salmonis. Front Microbiol 2021; 12:734239. [PMID: 34707589 PMCID: PMC8542936 DOI: 10.3389/fmicb.2021.734239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
Extensive use of antibiotics has been the primary treatment for the Salmonid Rickettsial Septicemia, a salmonid disease caused by the bacterium Piscirickettsia salmonis. Occurrence of antibiotic resistance has been explored in various P. salmonis isolates using different assays; however, P. salmonis is a nutritionally demanding intracellular facultative pathogen; thus, assessing its antibiotic susceptibility with standardized and validated protocols is essential. In this work, we studied the pathogen response to antibiotics using a genomic, a transcriptomic, and a phenotypic approach. A new defined medium (CMMAB) was developed based on a metabolic model of P. salmonis. CMMAB was formulated to increase bacterial growth in nutrient-limited conditions and to be suitable for performing antibiotic susceptibility tests. Antibiotic resistance was evaluated based on a comprehensive search of antibiotic resistance genes (ARGs) from P. salmonis genomes. Minimum inhibitory concentration assays were conducted to test the pathogen susceptibility to antibiotics from drug categories with predicted ARGs. In all tested P. salmonis strains, resistance to erythromycin, ampicillin, penicillin G, streptomycin, spectinomycin, polymyxin B, ceftazidime, and trimethoprim was medium-dependent, showing resistance to higher antibiotic concentrations in the CMMAB medium. The mechanism for antibiotic resistance to ampicillin in the defined medium was further explored and was proven to be associated to a decrease in the bacterial central metabolism, including the TCA cycle, the pentose-phosphate pathway, energy production, and nucleotide metabolism, and it was not associated with decreased growth rate of the bacterium or with the expression of any predicted ARG. Our results suggest that nutrient scarcity plays a role in the bacterial antibiotic resistance, protecting against the detrimental effects of antibiotics, and thus, we propose that P. salmonis exhibits a metabolic resistance to ampicillin when growing in a nutrient-limited medium.
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Affiliation(s)
- Javiera Ortiz-Severín
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
| | - Camila J Stuardo
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile
| | - Natalia E Jiménez
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Ricardo Palma
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - María P Cortés
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Jonathan Maldonado
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
| | - Alejandro Maass
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Verónica Cambiazo
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
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22
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Sanchez SE, Omsland A. Conditional impairment of Coxiella burnetii by glucose-6P dehydrogenase activity. Pathog Dis 2021; 79:6321164. [PMID: 34259815 PMCID: PMC8292140 DOI: 10.1093/femspd/ftab034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 07/06/2021] [Indexed: 11/12/2022] Open
Abstract
Coxiella burnetii is a bacterial obligate intracellular parasite and the etiological agent of query (Q) fever. While the C. burnetii genome has been reduced to ∼2 Mb as a likely consequence of genome streamlining in response to parasitism, enzymes for a nearly complete central metabolic machinery are encoded by the genome. However, lack of a canonical hexokinase for phosphorylation of glucose and an apparent absence of the oxidative branch of the pentose phosphate pathway, a major mechanism for regeneration of the reducing equivalent nicotinamide adenine dinucleotide phosphate (NADPH), have been noted as potential metabolic limitations of C. burnetii. By complementing C. burnetii with the gene zwf encoding the glucose-6-phosphate-consuming and NADPH-producing enzyme glucose-6-phosphate dehydrogenase (G6PD), we demonstrate a severe metabolic fitness defect for C. burnetii under conditions of glucose limitation. Supplementation of the medium with the gluconeogenic carbon source glutamate did not rescue the growth defect of bacteria complemented with zwf. Absence of G6PD in C. burnetii therefore likely relates to the negative effect of its activity under conditions of glucose limitation. Coxiella burnetii central metabolism with emphasis on glucose, NAD+, NADP+ and NADPH is discussed in a broader perspective, including comparisons with other bacterial obligate intracellular parasites.
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Affiliation(s)
- Savannah E Sanchez
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA 99164, USA.,School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - Anders Omsland
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA 99164, USA
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23
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The Coxiella burnetii QpH1 plasmid is a virulence factor for colonizing bone marrow-derived murine macrophages. J Bacteriol 2021; 203:JB.00588-20. [PMID: 33558394 PMCID: PMC8092169 DOI: 10.1128/jb.00588-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coxiella burnetii strains carry one of four large, conserved, autonomously replicating plasmids (QpH1, QpRS, QpDV, and QpDG) or a QpRS-like chromosomally integrated sequence of unknown function. Here we report the characterization of the QpH1 plasmid of C. burnetii Nine Mile phase II by making QpH1-deficient strains. A shuttle vector pQGK containing the CBUA0036-0039a region (predicted as being required for the QpH1 maintenance) was constructed. The pQGK vector can be stably transformed into the Nine Mile II and maintained at a similar low copy like QpH1. Importantly, transformation with pQGK cured the endogenous QpH1 due to plasmid incompatibility. Compared to a Nine Mile II transformant of a RSF1010-ori based vector, the pQGK transformant shows a similar growth curve in both axenic media and Buffalo green monkey kidney cells, a variable growth defect in macrophage-like THP-1 cells depending on the origin of inoculum, and dramatically reduced ability of colonizing wild-type bone marrow-derived murine macrophages. Furthermore, we found CBUA0037-0039 ORFs are essential for plasmid maintenance, and CBUA0037-0038 ORFs account for plasmid compatibility. And plasmid-deficient C. burnetii can be isolated by using CBUA0037 or -0038 deletion vectors. Furthermore, QpH1-deficient C. burnetii strains caused a lesser extent of splenomegaly in SCID mice but, intriguingly, they had significant growth in SCID mouse-sourced macrophages. Taken together, our data suggest that QpH1 encodes factor(s) essential for colonizing murine, not human, macrophages. This study suggests a critical role of QpH1 for C. burnetii persistence in rodents and expands the toolkit for the genetic studies in C. burnetii Author summary All C. burnetii isolates carry one of four large, conserved, autonomously replicating plasmids or a plasmid-like chromosomally integrated sequence. The plasmid is a candidate virulence factor of unknown function. Here we describe the construction of novel shuttle vectors that allow making plasmid-deficient C. burnetii mutants. With this plasmid-curing approach, we characterized the role of the QpH1 plasmid in in vitro and in vivo C. burnetii infection models. We found that the plasmid plays a critical role for C. burnetii growth in murine macrophages. Our work suggests an essential role of the QpH1 plasmid for the acquisition of colonizing capability in rodents by C. burnetii This study represents a major step toward unravelling the mystery of the C. burnetii cryptic plasmids.
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24
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Long CM, Beare PA, Cockrell DC, Fintzi J, Tesfamariam M, Shaia CI, Heinzen RA. Contributions of lipopolysaccharide and the type IVB secretion system to Coxiella burnetii vaccine efficacy and reactogenicity. NPJ Vaccines 2021; 6:38. [PMID: 33741986 PMCID: PMC7979919 DOI: 10.1038/s41541-021-00296-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 02/12/2021] [Indexed: 12/15/2022] Open
Abstract
Coxiella burnetii is the bacterial causative agent of the zoonosis Q fever. The current human Q fever vaccine, Q-VAX®, is a fixed, whole cell vaccine (WCV) licensed solely for use in Australia. C. burnetii WCV administration is associated with a dermal hypersensitivity reaction in people with pre-existing immunity to C. burnetii, limiting wider use. Consequently, a less reactogenic vaccine is needed. Here, we investigated contributions of the C. burnetii Dot/Icm type IVB secretion system (T4BSS) and lipopolysaccharide (LPS) in protection and reactogenicity of fixed WCVs. A 32.5 kb region containing 23 dot/icm genes was deleted in the virulent Nine Mile phase I (NMI) strain and the resulting mutant was evaluated in guinea pig models of C. burnetii infection, vaccination-challenge, and post-vaccination hypersensitivity. The NMI ∆dot/icm strain was avirulent, protective as a WCV against a robust C. burnetii challenge, and displayed potentially altered reactogenicity compared to NMI. Nine Mile phase II (NMII) strains of C. burnetii that produce rough LPS, were similarly tested. NMI was significantly more protective than NMII as a WCV; however, both vaccines exhibited similar reactogenicity. Collectively, our results indicate that, like phase I LPS, the T4BSS is required for full virulence by C. burnetii. Conversely, unlike phase I LPS, the T4BSS is not required for vaccine-induced protection. LPS length does not appear to contribute to reactogenicity while the T4BSS may contribute to this response. NMI ∆dot/icm represents an avirulent phase I strain with full vaccine efficacy, illustrating the potential of genetically modified C. burnetii as improved WCVs.
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Affiliation(s)
- Carrie M Long
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA.
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Diane C Cockrell
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Jonathan Fintzi
- Biostatistics Research Branch, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Mahelat Tesfamariam
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Carl I Shaia
- Rocky Mountain Veterinary Branch, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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25
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Protein and DNA Biosynthesis Demonstrated in Host Cell-Free Phagosomes Containing Anaplasma phagocytophilum or Ehrlichia chaffeensis in Axenic Media. Infect Immun 2021; 89:IAI.00638-20. [PMID: 33431703 PMCID: PMC8090944 DOI: 10.1128/iai.00638-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 12/23/2020] [Indexed: 11/20/2022] Open
Abstract
Rickettsiae belong to the Anaplasmataceae family, which includes mostly tick-transmitted pathogens causing human, canine, and ruminant diseases. Biochemical characterization of the pathogens remains a major challenge because of their obligate parasitism. Rickettsiae belong to the Anaplasmataceae family, which includes mostly tick-transmitted pathogens causing human, canine, and ruminant diseases. Biochemical characterization of the pathogens remains a major challenge because of their obligate parasitism. We investigated the use of an axenic medium for growth of two important pathogens—Anaplasma phagocytophilum and Ehrlichia chaffeensis—in host cell-free phagosomes. We recently reported that the axenic medium promotes protein and DNA biosynthesis in host cell-free replicating form of E. chaffeensis, although the bacterial replication is limited. We now tested the hypothesis that growth on axenic medium can be improved if host cell-free rickettsia-containing phagosomes are used. Purification of phagosomes from A. phagocytophilum- and E. chaffeensis-infected host cells was accomplished by density gradient centrifugation combined with magnet-assisted cell sorting. Protein and DNA synthesis was observed for both organisms in cell-free phagosomes with glucose-6-phosphate and/or ATP. The levels of protein and DNA synthesis were the highest for a medium pH of 7. The data demonstrate bacterial DNA and protein synthesis for the first time in host cell-free phagosomes for two rickettsial pathogens. The host cell support-free axenic growth of obligate pathogenic rickettsiae will be critical in advancing research goals in many important tick-borne diseases impacting human and animal health.
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26
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Fielden LF, Scott NE, Palmer CS, Khoo CA, Newton HJ, Stojanovski D. Proteomic Identification of Coxiella burnetii Effector Proteins Targeted to the Host Cell Mitochondria During Infection. Mol Cell Proteomics 2020; 20:100005. [PMID: 33177156 PMCID: PMC7950127 DOI: 10.1074/mcp.ra120.002370] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/11/2020] [Indexed: 11/06/2022] Open
Abstract
Modulation of the host cell is integral to the survival and replication of microbial pathogens. Several intracellular bacterial pathogens deliver bacterial proteins, termed "effector proteins" into the host cell during infection by sophisticated protein translocation systems, which manipulate cellular processes and functions. The functional contribution of individual effectors is poorly characterized, particularly in intracellular bacterial pathogens with large effector protein repertoires. Technical caveats have limited the capacity to study these proteins during a native infection, with many effector proteins having only been demonstrated to be translocated during over-expression of tagged versions. Here, we developed a novel strategy to examine effector proteins in the context of infection. We coupled a broad, unbiased proteomics-based screen with organelle purification to study the host-pathogen interactions occurring between the host cell mitochondrion and the Gram-negative, Q fever pathogen Coxiella burnetii. We identify four novel mitochondrially-targeted C. burnetii effector proteins, renamed Mitochondrial Coxiella effector protein (Mce) B to E. Examination of the subcellular localization of ectopically expressed proteins confirmed their mitochondrial localization, demonstrating the robustness of our approach. Subsequent biochemical analysis and affinity enrichment proteomics of one of these effector proteins, MceC, revealed the protein localizes to the inner membrane and can interact with components of the mitochondrial quality control machinery. Our study adapts high-sensitivity proteomics to study intracellular host-pathogen interactions, providing a robust strategy to examine the subcellular localization of effector proteins during native infection. This approach could be applied to a range of pathogens and host cell compartments to provide a rich map of effector dynamics throughout infection.
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Affiliation(s)
- Laura F Fielden
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Catherine S Palmer
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Chen Ai Khoo
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Hayley J Newton
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
| | - Diana Stojanovski
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
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27
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Pechstein J, Schulze-Luehrmann J, Bisle S, Cantet F, Beare PA, Ölke M, Bonazzi M, Berens C, Lührmann A. The Coxiella burnetii T4SS Effector AnkF Is Important for Intracellular Replication. Front Cell Infect Microbiol 2020; 10:559915. [PMID: 33282747 PMCID: PMC7691251 DOI: 10.3389/fcimb.2020.559915] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 10/19/2020] [Indexed: 12/20/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular pathogen and the causative agent of the zoonotic disease Q fever. Following uptake by alveolar macrophages, the pathogen replicates in an acidic phagolysosomal vacuole, the C. burnetii-containing vacuole (CCV). Effector proteins translocated into the host cell by the type IV secretion system (T4SS) are important for the establishment of the CCV. Here we focus on the effector protein AnkF and its role in establishing the CCV. The C. burnetii AnkF knock out mutant invades host cells as efficiently as wild-type C. burnetii, but this mutant is hampered in its ability to replicate intracellularly, indicating that AnkF might be involved in the development of a replicative CCV. To unravel the underlying reason(s), we searched for AnkF interactors in host cells and identified vimentin through a yeast two-hybrid approach. While AnkF does not alter vimentin expression at the mRNA or protein levels, the presence of AnkF results in structural reorganization and vesicular co-localization with recombinant vimentin. Ectopically expressed AnkF partially accumulates around the established CCV and endogenous vimentin is recruited to the CCV in a time-dependent manner, suggesting that AnkF might attract vimentin to the CCV. However, knocking-down endogenous vimentin does not affect intracellular replication of C. burnetii. Other cytoskeletal components are recruited to the CCV and might compensate for the lack of vimentin. Taken together, AnkF is essential for the establishment of the replicative CCV, however, its mode of action is still elusive.
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Affiliation(s)
- Julian Pechstein
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Stephanie Bisle
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Franck Cantet
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Centre National de la Recherche Scientifique (CNRS), Université de Montpellier, Montpellier, France
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Martha Ölke
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Matteo Bonazzi
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Centre National de la Recherche Scientifique (CNRS), Université de Montpellier, Montpellier, France
| | - Christian Berens
- Friedrich-Loeffler-Institut, Institut für Molekulare Pathogenese, Jena, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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28
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β-Barrel proteins tether the outer membrane in many Gram-negative bacteria. Nat Microbiol 2020; 6:19-26. [PMID: 33139883 PMCID: PMC7755725 DOI: 10.1038/s41564-020-00798-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 09/16/2020] [Indexed: 12/20/2022]
Abstract
Gram-negative bacteria have a cell envelope that comprises an outer membrane (OM), a peptidoglycan (PG) layer and an inner membrane (IM)1. The OM and PG are load-bearing, selectively permeable structures that are stabilized by cooperative interactions between IM and OM proteins2,3. In E. coli, Braun’s lipoprotein (Lpp) forms the only covalent tether between the OM and PG and is crucial for cell envelope stability4 but most other Gram-negative bacteria lack Lpp so it has been assumed that alternative mechanisms of OM stabilization are present5. We use a glycoproteomic analysis of PG to show that β-barrel OM proteins are covalently attached to PG in several Gram-negative species, including Coxiella burnetii, Agrobacterium tumefaciens and Legionella pneumophila. In C. burnetii, we found that four different types of covalent attachments occur between OM proteins and PG, with tethering of the β-barrel OM protein BbpA becoming most abundant in stationary phase and tethering of the lipoprotein LimB similar throughout the cell-cycle. Using a genetic approach, we demonstrate that the cell-cycle dependent tethering of BbpA is partly dependent on a developmentally regulated L,D transpeptidase (Ldt). We use our findings to propose a model of Gram-negative cell envelope stabilization that includes cell-cycle control and an expanded role for Ldts in covalently attaching surface proteins to PG.
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29
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Schäfer W, Schmidt T, Cordsmeier A, Borges V, Beare PA, Pechstein J, Schulze-Luehrmann J, Holzinger J, Wagner N, Berens C, Heydel C, Gomes JP, Lührmann A. The anti-apoptotic Coxiella burnetii effector protein AnkG is a strain specific virulence factor. Sci Rep 2020; 10:15396. [PMID: 32958854 PMCID: PMC7506536 DOI: 10.1038/s41598-020-72340-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 08/26/2020] [Indexed: 11/24/2022] Open
Abstract
The ability to inhibit host cell apoptosis is important for the intracellular replication of the obligate intracellular pathogen Coxiella burnetii, as it allows the completion of the lengthy bacterial replication cycle. Effector proteins injected into the host cell by the C. burnetii type IVB secretion system (T4BSS) are required for the inhibition of host cell apoptosis. AnkG is one of these anti-apoptotic effector proteins. The inhibitory effect of AnkG requires its nuclear localization, which depends on p32-dependent intracellular trafficking and importin-α1-mediated nuclear entry of AnkG. Here, we compared the sequences of ankG from 37 C. burnetii isolates and classified them in three groups based on the predicted protein size. The comparison of the three different groups allowed us to identify the first 28 amino acids as essential and sufficient for the anti-apoptotic activity of AnkG. Importantly, only the full-length protein from the first group is a bona fide effector protein injected into host cells during infection and has anti-apoptotic activity. Finally, using the Galleria mellonella infection model, we observed that AnkG from the first group has the ability to attenuate pathology during in vivo infection, as it allows survival of the larvae despite bacterial replication.
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Affiliation(s)
- Walter Schäfer
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Teresa Schmidt
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Arne Cordsmeier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Vítor Borges
- Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Julian Pechstein
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Jonas Holzinger
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Nicole Wagner
- Institut für Molekulare Pathogenese, Friedrich-Loeffler-Institut, 07743, Jena, Germany
| | - Christian Berens
- Institut für Molekulare Pathogenese, Friedrich-Loeffler-Institut, 07743, Jena, Germany
| | - Carsten Heydel
- Institut für Hygiene und Infektionskrankheiten der Tiere, Justus Liebig Universität Gießen, Frankfurter Straße 85-89, 35392, Gießen, Germany
| | - João Paulo Gomes
- Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany.
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30
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Coxiella burnetii utilizes both glutamate and glucose during infection with glucose uptake mediated by multiple transporters. Biochem J 2020; 476:2851-2867. [PMID: 31527117 PMCID: PMC6792032 DOI: 10.1042/bcj20190504] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/02/2019] [Accepted: 09/16/2019] [Indexed: 12/25/2022]
Abstract
Coxiella burnetii is a Gram-negative bacterium which causes Q fever, a complex and life-threatening infection with both acute and chronic presentations. C. burnetii invades a variety of host cell types and replicates within a unique vacuole derived from the host cell lysosome. In order to understand how C. burnetii survives within this intracellular niche, we have investigated the carbon metabolism of both intracellular and axenically cultivated bacteria. Both bacterial populations were shown to assimilate exogenous [13C]glucose or [13C]glutamate, with concomitant labeling of intermediates in glycolysis and gluconeogenesis, and in the TCA cycle. Significantly, the two populations displayed metabolic pathway profiles reflective of the nutrient availabilities within their propagated environments. Disruption of the C. burnetii glucose transporter, CBU0265, by transposon mutagenesis led to a significant decrease in [13C]glucose utilization but did not abolish glucose usage, suggesting that C. burnetii express additional hexose transporters which may be able to compensate for the loss of CBU0265. This was supported by intracellular infection of human cells and in vivo studies in the insect model showing loss of CBU0265 had no impact on intracellular replication or virulence. Using this mutagenesis and [13C]glucose labeling approach, we identified a second glucose transporter, CBU0347, the disruption of which also showed significant decreases in 13C-label incorporation but did not impact intracellular replication or virulence. Together, these analyses indicate that C. burnetii may use multiple carbon sources in vivo and exhibits greater metabolic flexibility than expected.
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Coxiella burnetii Requires Host Eukaryotic Initiation Factor 2α Activity for Efficient Intracellular Replication. Infect Immun 2020; 88:IAI.00096-20. [PMID: 32284364 DOI: 10.1128/iai.00096-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/09/2020] [Indexed: 02/06/2023] Open
Abstract
Coxiella burnetii is the causative agent of human Q fever, eliciting symptoms that range from acute fever and fatigue to chronic fatal endocarditis. C. burnetii is a Gram-negative intracellular bacterium that replicates within an acidic lysosome-like parasitophorous vacuole (PV) in human macrophages. During intracellular growth, C. burnetii delivers bacterial proteins directly into the host cytoplasm using a Dot/Icm type IV secretion system (T4SS). Multiple T4SS effectors localize to and/or disrupt the endoplasmic reticulum (ER) and secretory transport, but their role in infection is unknown. During microbial infection, unfolded nascent proteins may exceed the folding capacity of the ER, activating the unfolded protein response (UPR) and restoring the ER to its normal physiological state. A subset of intracellular pathogens manipulates the UPR to promote survival and replication in host cells. In this study, we investigated the impact of C. burnetii infection on activation of the three arms of the UPR. An inhibitor of the UPR antagonized PV expansion in macrophages, indicating this process is needed for bacterial replication niche formation. Protein kinase RNA-like ER kinase (PERK) signaling was activated during infection, leading to increased levels of phosphorylated eukaryotic initiation factor α, which was required for C. burnetii growth. Increased production and nuclear translocation of the transcription factor ATF4 also occurred, which normally drives expression of the proapoptotic C/EBP homologous protein (CHOP). CHOP protein production increased during infection; however, C. burnetii actively prevented CHOP nuclear translocation and downstream apoptosis in a T4SS-dependent manner. The results collectively demonstrate interplay between C. burnetii and specific components of the eIF2α signaling cascade to parasitize human macrophages.
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Cordsmeier A, Wagner N, Lührmann A, Berens C. Defying Death - How Coxiella burnetii Copes with Intentional Host Cell Suicide. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:619-628. [PMID: 31866777 PMCID: PMC6913804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The obligate intracellular pathogen Coxiella burnetii is the causative agent of the worldwide zoonotic disease Q fever. This Gram-negative bacterium infects macrophages where it establishes a replicative niche in an acidic and phagolysosome-like vacuole. Establishing and maintaining the niche requires a functional type IV secretion system (T4SS) which translocates multiple effector proteins into the host cell. These effector proteins act by manipulating diverse cellular processes allowing the bacterium to establish an infection and complete its complex biphasic developmental cycle. The lengthy nature of this life cycle suggests that C. burnetii has to successfully deal with cellular defense processes. Cell death is one mechanism infected cells frequently utilize to control or to at least minimize the impact of an infection. To date, four effector proteins have been identified in C. burnetii, which interfere with the induction of cell death. Three, AnkG, CaeA, and CaeB, affect intrinsic apoptosis, CaeA additionally extrinsic apoptosis. The proteins target different steps of the apoptotic pathway and are not conserved among isolates suggesting redundancy as an important feature of cell death inhibition. The fourth effector protein, IcaA, interferes with the non-canonical pathway of pyroptosis, an important inflammatory cell death pathway for controlling infectious disease. Autophagy is relevant for the C. burnetii life-cycle, but to which extent autophagic cell death is a factor in bacterial survival and proliferation is still not clear. To convincingly understand how bacterial manipulation of autophagy affects cell death either directly or indirectly will require further experiments. Collectively, C. burnetii modulates the extrinsic and intrinsic apoptotic pathways and non-canonical pyroptosis to inhibit host cell death, thereby providing a stable, intracellular niche for the course of the pathogen's infectious cycle.
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Affiliation(s)
- Arne Cordsmeier
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nicole Wagner
- Institut für molekulare Pathogenese, Friedrich-Loeffler-Institut, Jena, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Berens
- Institut für molekulare Pathogenese, Friedrich-Loeffler-Institut, Jena, Germany,To whom all correspondence should be addressed: Christian Berens, Institut für molekulare Pathogenese, Friedrich-Loeffler-Institut, Naumburger Str. 96a, 07743 Jena, Germany; Tel: +49-3641-804-2500, Fax: +49-3641-804-2482, E-mail:
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Long CM, Beare PA, Cockrell DC, Larson CL, Heinzen RA. Comparative virulence of diverse Coxiella burnetii strains. Virulence 2019; 10:133-150. [PMID: 30782062 PMCID: PMC6389282 DOI: 10.1080/21505594.2019.1575715] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/31/2022] Open
Abstract
Coxiella burnetii is an intracellular, gram-negative bacterium that causes the zoonosis Q fever. This disease typically presents as an acute flu-like illness with persistent, focalized infections occurring less frequently. Clinical outcomes of Q fever have been associated with distinct genomic groups of C. burnetii, suggesting that gene content is responsible for virulence potential. To investigate this hypothesis, the virulence of thirteen C. burnetii strains (representing genomic groups I-VI) was evaluated in a guinea pig infection model by intraperitoneal injection. Seven strains caused a sustained fever (at least two days ≥39.5°C) in at least half of the animals within each experimental group. At fourteen days post infection, animals were euthanized and additional endpoints were evaluated, including splenomegaly and serology. The magnitude of these endpoints roughly correlated with the onset, duration, and severity of fever. The most severe disease was caused by group I strains. Intermediate and no virulence were evidenced following infection with group II-V and group VI strains, respectively. Flow cytometric analysis of the mesenteric lymph nodes revealed decreased CD4+ T cell frequency following infection with highly virulent group I strains. These findings buttress the hypothesis that the pathogenic potential of C. burnetii strains correlates with genomic grouping. These data, combined with comparative genomics and genetic manipulation, will improve our understanding of C. burnetii virulence determinants.
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Affiliation(s)
- Carrie M Long
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Diane C Cockrell
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Charles L Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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Ledbetter L, Cherla R, Chambers C, Zhang Y, Zhang G. Eosinophils Affect Antibody Isotype Switching and May Partially Contribute to Early Vaccine-Induced Immunity against Coxiella burnetii. Infect Immun 2019; 87:e00376-19. [PMID: 31427447 PMCID: PMC6803328 DOI: 10.1128/iai.00376-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/09/2019] [Indexed: 01/21/2023] Open
Abstract
Coxiella burnetii is an obligate intracellular Gram-negative bacterium which causes human Q fever. An acidified citrate cysteine medium (ACCM-2) has been developed which mimics the intracellular replicative niche of C. burnetii and allows axenic growth of the bacteria. To determine if C. burnetii cultured in ACCM-2 retains immunogenicity, we compared the protective efficacies of formalin-inactivated C. burnetii Nine Mile phase I (PIV) and phase II (PIIV) vaccines derived from axenic culture 7, 14, and 28 days postvaccination. PIV conferred significant protection against virulent C. burnetii as early as 7 days postvaccination, which suggests that ACCM-2-derived PIV retains immunogenicity and protectivity. We analyzed the cellular immune response in spleens from PIV- and PIIV-vaccinated mice by flow cytometry at 7 and 14 days postvaccination and found significantly more granulocytes in PIV-vaccinated mice than in PIIV-vaccinated mice. Interestingly, we found these infiltrating granulocytes to be SSChigh CD11b+ CD125+ Siglec-F+ (where SSChigh indicates a high side scatter phenotype) eosinophils. There was no change in the number of eosinophils in PIV-vaccinated CD4-deficient mice compared to the level in controls, which suggests that eosinophil accumulation is CD4+ T cell dependent. To evaluate the importance of eosinophils in PIV-mediated protection, we vaccinated and challenged eosinophil-deficient ΔdblGATA mice. ΔdblGATA mice had significantly worse disease than their wild-type counterparts when challenged 7 days postvaccination, while no significant difference was seen at 28 days postvaccination. Nevertheless, ΔdblGATA mice had elevated serum IgM with decreased IgG1 and IgG2a whether mice were challenged at 7 or 28 days postvaccination. These results suggest that eosinophils may play a role in early vaccine protection against C. burnetii and contribute to antibody isotype switching.
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Affiliation(s)
- Lindsey Ledbetter
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
| | - Rama Cherla
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
| | - Catherine Chambers
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
| | - Yan Zhang
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
| | - Guoquan Zhang
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA
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Miller HE, Hoyt FH, Heinzen RA. Replication of Coxiella burnetii in a Lysosome-Like Vacuole Does Not Require Lysosomal Hydrolases. Infect Immun 2019; 87:e00493-19. [PMID: 31405956 PMCID: PMC6803326 DOI: 10.1128/iai.00493-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/06/2019] [Indexed: 01/03/2023] Open
Abstract
Coxiella burnetii is an intracellular bacterium that causes query, or Q fever, a disease that typically manifests as a severe flu-like illness. The initial target of C. burnetii is the alveolar macrophage. Here, it regulates vesicle trafficking pathways and fusion events to establish a large replication vacuole called the Coxiella-containing vacuole (CCV). Similar to a phagolysosome, the CCV has an acidic pH and contains lysosomal hydrolases obtained via fusion with late endocytic vesicles. Lysosomal hydrolases break down various lipids, carbohydrates, and proteins; thus, it is assumed C. burnetii derives nutrients for growth from these degradation products. To investigate this possibility, we utilized a GNPTAB-/- HeLa cell line that lacks lysosomal hydrolases in endocytic compartments. Unexpectedly, examination of C. burnetii growth in GNPTAB-/- HeLa cells revealed replication and viability are not impaired, indicating C. burnetii does not require by-products of hydrolase degradation to survive and grow in the CCV. However, although bacterial growth was normal, CCVs were abnormal, appearing dark and condensed rather than clear and spacious. Lack of degradation within CCVs allowed waste products to accumulate, including intraluminal vesicles, autophagy protein LC3, and cholesterol. The build-up of waste products coincided with an altered CCV membrane, where LAMP1 was decreased and CD63 and LAMP1 redistributed from a punctate to uniform localization. This disruption of CCV membrane organization may account for the decreased CCV size due to impaired fusion with late endocytic vesicles. Collectively, these results demonstrate lysosomal hydrolases are not required for C. burnetii survival and growth but are needed for normal CCV development. These data provide insight into mechanisms of CCV biogenesis while raising the important question of how C. burnetii obtains essential nutrients from its host.
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Affiliation(s)
- Heather E Miller
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Forrest H Hoyt
- Electron Microscopy Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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A CsrA-Binding, trans-Acting sRNA of Coxiella burnetii Is Necessary for Optimal Intracellular Growth and Vacuole Formation during Early Infection of Host Cells. J Bacteriol 2019; 201:JB.00524-19. [PMID: 31451541 DOI: 10.1128/jb.00524-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 08/17/2019] [Indexed: 11/20/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular gammaproteobacterium and zoonotic agent of Q fever. We previously identified 15 small noncoding RNAs (sRNAs) of C. burnetii One of them, CbsR12 (Coxiella burnetii small RNA 12), is highly transcribed during axenic growth and becomes more prominent during infection of cultured mammalian cells. Secondary structure predictions of CbsR12 revealed four putative CsrA-binding sites in stem loops with consensus AGGA/ANGGA motifs. We subsequently determined that CbsR12 binds to recombinant C. burnetii CsrA-2, but not CsrA-1, proteins in vitro Moreover, through a combination of in vitro and cell culture assays, we identified several in trans mRNA targets of CbsR12. Of these, we determined that CbsR12 binds and upregulates translation of carA transcripts coding for carbamoyl phosphate synthetase A, an enzyme that catalyzes the first step of pyrimidine biosynthesis. In addition, CbsR12 binds and downregulates translation of metK transcripts coding for S-adenosylmethionine synthetase, a component of the methionine cycle. Furthermore, we found that CbsR12 binds to and downregulates the quantity of cvpD transcripts, coding for a type IVB effector protein, in mammalian cell culture. Finally, we found that CbsR12 is necessary for expansion of Coxiella-containing vacuoles and affects growth rates in a dose-dependent manner in the early phase of infecting THP-1 cells. This is the first characterization of a trans-acting sRNA of C. burnetii and the first example of a bacterial sRNA that regulates both CarA and MetK synthesis. CbsR12 is one of only a few identified trans-acting sRNAs that interacts with CsrA.IMPORTANCE Regulation of metabolism and virulence in C. burnetii is not well understood. Here, we show that C. burnetii small RNA 12 (CbsR12) is highly transcribed in the metabolically active large-cell variant compared to the nonreplicative small-cell variant. We show that CbsR12 directly regulates several genes involved in metabolism, along with a type IV effector gene, in trans In addition, we demonstrate that CbsR12 binds to CsrA-2 in vitro and induces autoaggregation and biofilm formation when transcribed ectopically in Escherichia coli, consistent with other CsrA-sequestering sRNAs. These results implicate CbsR12 in the indirect regulation of a number of genes via CsrA-mediated regulatory activities. The results also support CbsR12 as a crucial regulatory component early on in a mammalian cell infection.
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Dresler J, Klimentova J, Pajer P, Salovska B, Fucikova AM, Chmel M, Schmoock G, Neubauer H, Mertens-Scholz K. Quantitative Proteome Profiling of Coxiella burnetii Reveals Major Metabolic and Stress Differences Under Axenic and Cell Culture Cultivation. Front Microbiol 2019; 10:2022. [PMID: 31620097 PMCID: PMC6759588 DOI: 10.3389/fmicb.2019.02022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/19/2019] [Indexed: 12/14/2022] Open
Abstract
Coxiella burnetii is the causative agent of the zoonotic disease Q fever. To date, the lipopolysaccharide (LPS) is the only defined and characterized virulence determinant of C. burnetii. In this study, proteome profiles of C. burnetii Nine Mile phase I (RSA 493, NMI) and its isogenic Nine Mile phase II (RSA 439 NMII) isolate with a deep rough LPS were compared on L-929 mouse fibroblasts and in complex (ACCM-2), and defined (ACCM-D) media. Whole proteome extracts were analyzed using a label-free quantification approach. Between 659 and 1,046 C. burnetii proteins of the 2,132 annotated coding sequences (CDS) were identified in any particular experiment. Proteome profiles clustered according to the cultivation conditions used, indicating different regulation patterns. NMI proteome profiles compared to NMII in ACCM-D indicate transition from an exponential to a stationary phase. The levels of regulatory proteins such as RpoS, CsrA2, UspA1, and UspA2 were increased. Comparison of the oxidative stress response of NMI and NMII indicated that ACCM-2 represents a high oxidative stress environment. Expression of peroxidases, superoxide dismutases, as well as thioredoxins was increased for NMI. In contrast, in ACCM-D, only osmoregulation seems to be necessary. Proteome profiles of NMII do not differ and indicate that both axenic media represent similar oxidative stress environments. Deep rough LPS causes changes of the outer membrane stability and fluidity. This might be one reason for the observed differences. Proteins associated with the T4SS and Sec translocon as well as several effector proteins were detectable under all three conditions. Interestingly, none of these putatively secreted proteins are upregulated in ACCM-2 compared to ACCM-D, and L-929 mouse fibroblasts. Curiously, a higher similarity of proteomic patterns (overlapping up- and downregulated proteins) of ACCM-D and bacteria grown in cell culture was observed. Particularly, the proteins involved in a better adaptation or homeostasis in response to the harsh environment of the parasitophorous vacuole were demonstrated for NMI. This semi-quantitative proteomic analysis of C. burnetii compared axenically grown bacteria to those propagated in cell culture.
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Affiliation(s)
| | - Jana Klimentova
- Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Petr Pajer
- Military Health Institute, Prague, Czechia
| | - Barbora Salovska
- Department of Genome Integrity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | | | - Martin Chmel
- Department of Infectious Diseases, First Faculty of Medicine, Charles University and Military University Hospital Prague, Prague, Czechia
| | - Gernot Schmoock
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Heinrich Neubauer
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Katja Mertens-Scholz
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
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Ganesan S, Roy CR. Host cell depletion of tryptophan by IFNγ-induced Indoleamine 2,3-dioxygenase 1 (IDO1) inhibits lysosomal replication of Coxiella burnetii. PLoS Pathog 2019; 15:e1007955. [PMID: 31461509 PMCID: PMC6736304 DOI: 10.1371/journal.ppat.1007955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 09/10/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
Most intracellular pathogens that reside in a vacuole prevent transit of their compartment to lysosomal organelles. Effector mechanisms induced by the pro-inflammatory cytokine Interferon-gamma (IFNγ) can promote the delivery of pathogen-occupied vacuoles to lysosomes for proteolytic degradation and are therefore important for host defense against intracellular pathogens. The bacterial pathogen Coxiella burnetii is unique in that, transport to the lysosome is essential for replication. The bacterium modulates membrane traffic to create a specialized autophagolysosomal compartment called the Coxiella-containing vacuole (CCV). Importantly, IFNγ signaling inhibits intracellular replication of C. burnetii, raising the question of which IFNγ-activated mechanisms restrict replication of a lysosome-adapted pathogen. To address this question, siRNA was used to silence a panel of IFNγ-induced genes in HeLa cells to identify genes required for restriction of C. burnetii intracellular replication. This screen demonstrated that Indoleamine 2,3-dioxygenase 1 (IDO1) contributes to IFNγ-mediated restriction of C. burnetii. IDO1 is an enzyme that catabolizes cellular tryptophan to kynurenine metabolites thereby reducing tryptophan availability in cells. Cells deficient in IDO1 function were more permissive for C. burnetii replication when treated with IFNγ, and supplementing IFNγ-treated cells with tryptophan enhanced intracellular replication. Additionally, ectopic expression of IDO1 in host cells was sufficient to restrict replication of C. burnetii in the absence of IFNγ signaling. Using differentiated THP1 macrophage-like cells it was determined that IFNγ-activation resulted in IDO1 production, and that supplementation of IFNγ-activated THP1 cells with tryptophan enhanced C. burnetii replication. Thus, this study identifies IDO1 production as a key cell-autonomous defense mechanism that limits infection by C. burnetii, which suggests that peptides derived from hydrolysis of proteins in the CCV do not provide an adequate supply of tryptophan for bacterial replication.
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Affiliation(s)
- Sandhya Ganesan
- Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Craig R. Roy
- Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
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Coxiella burnetii RpoS Regulates Genes Involved in Morphological Differentiation and Intracellular Growth. J Bacteriol 2019; 201:JB.00009-19. [PMID: 30745369 DOI: 10.1128/jb.00009-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 01/30/2019] [Indexed: 12/19/2022] Open
Abstract
Coxiella burnetii, the etiological agent of Q fever, undergoes a unique biphasic developmental cycle where bacteria transition from a replicating (exponential-phase) large cell variant (LCV) form to a nonreplicating (stationary-phase) small cell variant (SCV) form. The alternative sigma factor RpoS is an essential regulator of stress responses and stationary-phase physiology in several bacterial species, including Legionella pneumophila, which has a developmental cycle superficially similar to that of C. burnetii Here, we used a C. burnetii ΔrpoS mutant to define the role of RpoS in intracellular growth and SCV development. Growth yields following infection of Vero epithelial cells or THP-1 macrophage-like cells with the rpoS mutant in the SCV form, but not the LCV form, were significantly lower than that of wild-type bacteria. RNA sequencing and whole-cell mass spectrometry of the C. burnetii ΔrpoS mutant revealed that a substantial portion of the C. burnetii genome is regulated by RpoS during SCV development. Regulated genes include those involved in stress responses, arginine transport, peptidoglycan remodeling, and synthesis of the SCV-specific protein ScvA. Genes comprising the dot/icm locus, responsible for production of the Dot/Icm type 4B secretion system, were also dysregulated in the rpoS mutant. These data were corroborated with independent assays demonstrating that the C. burnetii ΔrpoS strain has increased sensitivity to hydrogen peroxide and carbenicillin and a thinner cell wall/outer membrane complex. Collectively, these results demonstrate that RpoS is an important regulator of genes involved in C. burnetii SCV development and intracellular growth.IMPORTANCE The Q fever bacterium Coxiella burnetii has spore-like environmental stability, a characteristic that contributes to its designation as a potential bioweapon. Stability is likely conferred by a highly resistant, small cell variant (SCV) stationary-phase form that arises during a biphasic developmental cycle. Here, we define the role of the alternative sigma factor RpoS in regulating genes associated with SCV development. Genes involved in stress responses, amino acid transport, cell wall remodeling, and type 4B effector secretion were dysregulated in the rpoS mutant. Cellular impairments included defects in intracellular growth, cell wall structure, and resistance to oxidants. These results support RpoS as a central regulator of the Coxiella developmental cycle and identify developmentally regulated genes involved in morphological differentiation.
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Noncanonical Inhibition of mTORC1 by Coxiella burnetii Promotes Replication within a Phagolysosome-Like Vacuole. mBio 2019; 10:mBio.02816-18. [PMID: 30723133 PMCID: PMC6428759 DOI: 10.1128/mbio.02816-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Coxiella burnetii is an intracellular pathogenic bacterium that replicates within a lysosomal vacuole. Biogenesis of the Coxiella-containing vacuole (CCV) requires effector proteins delivered into the host cell cytosol by the type 4B secretion system (T4BSS). Modifications to lysosomal physiology required for pathogen replication within the CCV are poorly understood. Mammalian (or mechanistic) target of rapamycin complex 1 (mTORC1) is a master kinase that regulates lysosome structure and function. Nutrient deprivation inhibits mTORC1, which promotes cell catabolism in the form of accelerated autophagy and increased lysosome biosynthesis. Here, we report that C. burnetii growth is enhanced by T4BSS-dependent inhibition of mTORC1 that does not activate autophagy. Canonical inhibition of mTORC1 by starvation or inhibitor treatment that induces autophagic flux does not benefit C. burnetii growth. Furthermore, hyperactivation of mTORC1 impairs bacterial replication. These findings indicate that C. burnetii inhibition of mTORC1 without accelerated autophagy promotes bacterial growth. The Q fever agent Coxiella burnetii is a Gram-negative bacterium that invades macrophages and replicates inside a specialized lysosomal vacuole. The pathogen employs a type 4B secretion system (T4BSS) to deliver effector proteins into the host cell that modify the Coxiella-containing vacuole (CCV) into a replication-permissive niche. Mature CCVs are massive degradative organelles that acquire lysosomal proteins. Inhibition of mammalian (or mechanistic) target of rapamycin complex 1 (mTORC1) kinase by nutrient deprivation promotes autophagy and lysosome fusion, as well as activation of the transcription factors TFE3 and TFEB (TFE3/B), which upregulates expression of lysosomal genes. Here, we report that C. burnetii inhibits mTORC1 as evidenced by impaired localization of mTORC1 to endolysosomal membranes and decreased phosphorylation of elF4E-binding protein 1 (4E-BP1) and S6 kinase 1 in infected cells. Infected cells exhibit increased amounts of autophagy-related proteins protein 1A/1B-light chain 3 (LC3) and p62 as well as of activated TFE3. However, C. burnetii did not accelerate autophagy or block autophagic flux triggered by cell starvation. Activation of autophagy or transcription by TFE3/B increased CCV expansion without enhancing bacterial replication. By contrast, knockdown of tuberous sclerosis complex 1 (TSC1) or TSC2, which hyperactivates mTORC1, impaired CCV expansion and bacterial replication. Together, these data demonstrate that specific inhibition of mTORC1 by C. burnetii, but not amplified cell catabolism via autophagy, is required for optimal pathogen replication. These data reveal a complex interplay between lysosomal function and host cell metabolism that regulates C. burnetii intracellular growth.
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Hayek I, Berens C, Lührmann A. Modulation of host cell metabolism by T4SS-encoding intracellular pathogens. Curr Opin Microbiol 2019; 47:59-65. [PMID: 30640035 DOI: 10.1016/j.mib.2018.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 11/22/2018] [Accepted: 11/29/2018] [Indexed: 12/26/2022]
Abstract
Intracellular bacterial pathogens intimately interact with the infected host cell to prevent elimination and to ensure survival. One group of intracellular pathogens, including Coxiella burnetii, Legionella pneumophila, Brucella spp., Anaplasma phagocytophilum, and Ehrlichia chaffeensis, utilizes a type IV secretion system (T4SS) that injects effectors to modulate host cell signalling, vesicular trafficking, autophagy, cell death and transcription to ensure survival [1]. So far, little emphasis has been directed towards understanding how these bacteria manipulate host cell metabolism. This manipulation is not only important for gaining access to nutrients, but also for regulating specific virulence programs [2,3]. Here, we will summarize recent progress made in characterizing the manipulation of host cell metabolism by C. burnetii and other intracellular pathogens utilizing a T4SS.
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Affiliation(s)
- Inaya Hayek
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Wasserturmstraße 3/5, D-91054 Erlangen, Germany
| | - Christian Berens
- Institut für molekulare Pathogenese, Friedrich-Loeffler-Institut, Naumburger Str. 96a, D-07743 Jena, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Wasserturmstraße 3/5, D-91054 Erlangen, Germany.
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Protein and DNA synthesis demonstrated in cell-free Ehrlichia chaffeensis organisms in axenic medium. Sci Rep 2018; 8:9293. [PMID: 29915240 PMCID: PMC6006305 DOI: 10.1038/s41598-018-27574-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/30/2018] [Indexed: 01/23/2023] Open
Abstract
Ehrlichia chaffeensis, a tick-transmitted rickettsial bacterium, is the causative agent of human monocytic ehrlichiosis. Biochemical characterization of this and other related Rickettsiales remains a major challenge, as they require a host cell for their replication. We investigated the use of an axenic medium for E. chaffeensis growth, assessed by protein and DNA synthesis, in the absence of a host cell. E. chaffeensis organisms harvested from in vitro cultures grown in a vertebrate cell line were fractionated into infectious dense-core cells (DC) and the non-infectious replicating form, known as reticulate cells (RC) by renografin density gradient centrifugation and incubated in the axenic medium containing amino acids, nucleotides, and different energy sources. Bacterial protein and DNA synthesis were observed in RCs in response to glucose-6-phosphate, although adenosine triphosphate, alpha-ketoglutarate or sodium acetate supported protein synthesis. The biosynthetic activity could not be detected in DCs in the axenic medium. While the data demonstrate de novo protein and DNA synthesis under axenic conditions for E. chaffeensis RCs, additional modifications are required in order to establish conditions that support bacterial replication, and transition to DCs.
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Wang T, Yu Y, Liang X, Luo S, He Z, Sun Z, Jiang Y, Omsland A, Zhou P, Song L. Lipid A Has Significance for Optimal Growth of Coxiella burnetii in Macrophage-Like THP-1 Cells and to a Lesser Extent in Axenic Media and Non-phagocytic Cells. Front Cell Infect Microbiol 2018; 8:192. [PMID: 29938202 PMCID: PMC6002510 DOI: 10.3389/fcimb.2018.00192] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 05/22/2018] [Indexed: 02/02/2023] Open
Abstract
Lipid A is an essential basal component of lipopolysaccharide of most Gram-negative bacteria. Inhibitors targeting LpxC, a conserved enzyme in lipid A biosynthesis, are antibiotic candidates against Gram-negative pathogens. Here we report the characterization of the role of lipid A in Coxiella burnetii growth in axenic media, monkey kidney cells (BGMK and Vero), and macrophage-like THP-1 cells by using a potent LpxC inhibitor -LPC-011. We first determined the susceptibility of C. burnetii LpxC to LPC-011 in a surrogate E. coli model. In E. coli, the minimum inhibitory concentration (MIC) of LPC-011 against C. burnetii LpxC is < 0.05 μg/mL, a value lower than the inhibitor's MIC against E. coli LpxC. Considering the inhibitor's problematic pharmacokinetic properties in vivo and Coxiella's culturing time up to 7 days, the stability of LPC-011 in cell cultures was assessed. We found that regularly changing inhibitor-containing media was required for sustained inhibition of C. burnetii LpxC in cells. Under inhibitor treatment, Coxiella has reduced growth yields in axenic media and during replication in non-phagocytic cells, and has a reduced number of productive vacuoles in such cells. Inhibiting lipid A biosynthesis in C. burnetii by the inhibitor was shown in a phase II strain transformed with chlamydial kdtA. This exogenous KdtA enzyme modifies Coxiella lipid A with an α-Kdo-(2 → 8)-α-Kdo epitope that can be detected by anti-chlamydia genus antibodies. In inhibitor-treated THP-1 cells, Coxiella shows severe growth defects characterized by poor vacuole formation and low growth yields. Coxiella progenies prepared from inhibitor-treated cells retain the capability of normally infecting all tested cells in the absence of the inhibitor, which suggests a dispensable role of lipid A for infection and early vacuole development. In conclusion, our data suggest that lipid A has significance for optimal development of Coxiella-containing vacuoles, and for robust multiplication of C. burnetii in macrophage-like THP-1 cells. Unlike many bacteria, C. burnetii replication in axenic media and non-phagocytic cells was less dependent on normal lipid A biosynthesis.
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Affiliation(s)
- Tao Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaofei Liang
- Department of Chemistry, Duke University, Durham, NC, United States
| | - Shengdong Luo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zemin He
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhihui Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yongqiang Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Lihua Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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Sanchez SE, Vallejo-Esquerra E, Omsland A. Use of Axenic Culture Tools to StudyCoxiella burnetii. ACTA ACUST UNITED AC 2018; 50:e52. [DOI: 10.1002/cpmc.52] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Savannah E. Sanchez
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University; Pullman Washington
| | - Eduardo Vallejo-Esquerra
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
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Beare PA, Jeffrey BM, Long CM, Martens CM, Heinzen RA. Genetic mechanisms of Coxiella burnetii lipopolysaccharide phase variation. PLoS Pathog 2018; 14:e1006922. [PMID: 29481553 PMCID: PMC5843353 DOI: 10.1371/journal.ppat.1006922] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/08/2018] [Accepted: 02/05/2018] [Indexed: 12/30/2022] Open
Abstract
Coxiella burnetii is an intracellular pathogen that causes human Q fever, a disease that normally presents as a severe flu-like illness. Due to high infectivity and disease severity, the pathogen is considered a risk group 3 organism. Full-length lipopolysaccharide (LPS) is required for full virulence and disease by C. burnetii and is the only virulence factor currently defined by infection of an immunocompetent animal. Transition of virulent phase I bacteria with smooth LPS, to avirulent phase II bacteria with rough LPS, occurs during in vitro passage. Semi-rough intermediate forms are also observed. Here, the genetic basis of LPS phase conversion was investigated to obtain a more complete understanding of C. burnetii pathogenesis. Whole genome sequencing of strains producing intermediate and/or phase II LPS identified several common mutations in predicted LPS biosynthesis genes. After passage in broth culture for 30 weeks, phase I strains from different genomic groups exhibited similar phase transition kinetics and elevation of mutations in LPS biosynthesis genes. Targeted mutagenesis and genetic complementation using a new C. burnetii nutritional selection system based on lysine auxotrophy confirmed that six of the mutated genes were necessary for production of phase I LPS. Disruption of two of these genes in a C. burnetii phase I strain resulted in production of phase II LPS, suggesting inhibition of the encoded enzymes could represent a new therapeutic strategy for treatment of Q fever. Additionally, targeted mutagenesis of genes encoding LPS biosynthesis enzymes can now be used to construct new phase II strains from different genomic groups for use in pathogen-host studies at a risk group 2 level.
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Affiliation(s)
- Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Brendan M. Jeffrey
- Bioinformatics and Computational Biosciences Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Carrie M. Long
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Craig M. Martens
- Research Technologies Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
- * E-mail:
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Mori M, Mertens K, Cutler SJ, Santos AS. Critical Aspects for Detection of Coxiella burnetii. Vector Borne Zoonotic Dis 2017; 17:33-41. [PMID: 28055578 DOI: 10.1089/vbz.2016.1958] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Coxiella burnetii is a globally distributed zoonotic γ-proteobacterium with an obligatory intracellular lifestyle. It is the causative agent of Q fever in humans and of coxiellosis among ruminants, although the agent is also detected in ticks, birds, and various other mammalian species. Requirements for intracellular multiplication together with the necessity for biosafety level 3 facilities restrict the cultivation of C. burnetii to specialized laboratories. Development of a novel medium formulation enabling axenic growth of C. burnetii has facilitated fundamental genetic studies. This review provides critical insights into direct diagnostic methods currently available for C. burnetii. It encompasses molecular detection methods, isolation, and propagation of the bacteria and its genetic characterization. Differentiation of C. burnetii from Coxiella-like organisms is an essential diagnostic prerequisite, particularly when handling and analyzing ticks.
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Affiliation(s)
- Marcella Mori
- 1 Bacterial Zoonoses of Livestock, Operational Directorate Bacterial Diseases, Veterinary and Agrochemical Research Centre, CODA-CERVA , Brussels, Belgium .,2 Belgian Reference Centre for Coxiella burnetii and Bartonella , Brussels, Belgium
| | - Katja Mertens
- 3 Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute for Bacterial Infections and Zoonoses , Jena, Germany
| | | | - Ana Sofia Santos
- 5 Centre for Vector and Infectious Diseases Research, National Institute of Health Doutor Ricardo Jorge , Águas de Moura, Portugal
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Häuslein I, Cantet F, Reschke S, Chen F, Bonazzi M, Eisenreich W. Multiple Substrate Usage of Coxiella burnetii to Feed a Bipartite Metabolic Network. Front Cell Infect Microbiol 2017; 7:285. [PMID: 28706879 PMCID: PMC5489692 DOI: 10.3389/fcimb.2017.00285] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 06/12/2017] [Indexed: 12/24/2022] Open
Abstract
The human pathogen Coxiella burnetii causes Q-fever and is classified as a category B bio-weapon. Exploiting the development of the axenic growth medium ACCM-2, we have now used 13C-labeling experiments and isotopolog profiling to investigate the highly diverse metabolic network of C. burnetii. To this aim, C. burnetii RSA 439 NMII was cultured in ACCM-2 containing 5 mM of either [U-13C3]serine, [U-13C6]glucose, or [U-13C3]glycerol until the late-logarithmic phase. GC/MS-based isotopolog profiling of protein-derived amino acids, methanol-soluble polar metabolites, fatty acids, and cell wall components (e.g., diaminopimelate and sugars) from the labeled bacteria revealed differential incorporation rates and isotopolog profiles. These data served to decipher the diverse usages of the labeled substrates and the relative carbon fluxes into the core metabolism of the pathogen. Whereas, de novo biosynthesis from any of these substrates could not be found for histidine, isoleucine, leucine, lysine, phenylalanine, proline and valine, the other amino acids and metabolites under study acquired 13C-label at specific rates depending on the nature of the tracer compound. Glucose was directly used for cell wall biosynthesis, but was also converted into pyruvate (and its downstream metabolites) through the glycolytic pathway or into erythrose 4-phosphate (e.g., for the biosynthesis of tyrosine) via the non-oxidative pentose phosphate pathway. Glycerol efficiently served as a gluconeogenetic substrate and could also be used via phosphoenolpyruvate and diaminopimelate as a major carbon source for cell wall biosynthesis. In contrast, exogenous serine was mainly utilized in downstream metabolic processes, e.g., via acetyl-CoA in a complete citrate cycle with fluxes in the oxidative direction and as a carbon feed for fatty acid biosynthesis. In summary, the data reflect multiple and differential substrate usages by C. burnetii in a bipartite-type metabolic network, resembling the overall topology of the related pathogen Legionella pneumophila. These strategies could benefit the metabolic capacities of the pathogens also as a trait to adapt for replication under intracellular conditions.
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Affiliation(s)
- Ina Häuslein
- Department of Chemistry, Chair of Biochemistry, Technische Universität MünchenGarching, Germany
| | - Franck Cantet
- IRIM-UMR 9004, Infectious Disease Research Institute of Montpellier, Université de Montpellier, Centre National de la Recherche ScientifiqueMontpellier, France
| | - Sarah Reschke
- Department of Chemistry, Chair of Biochemistry, Technische Universität MünchenGarching, Germany
| | - Fan Chen
- Department of Chemistry, Chair of Biochemistry, Technische Universität MünchenGarching, Germany
| | - Matteo Bonazzi
- IRIM-UMR 9004, Infectious Disease Research Institute of Montpellier, Université de Montpellier, Centre National de la Recherche ScientifiqueMontpellier, France
| | - Wolfgang Eisenreich
- Department of Chemistry, Chair of Biochemistry, Technische Universität MünchenGarching, Germany
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Vallejo Esquerra E, Yang H, Sanchez SE, Omsland A. Physicochemical and Nutritional Requirements for Axenic Replication Suggest Physiological Basis for Coxiella burnetii Niche Restriction. Front Cell Infect Microbiol 2017; 7:190. [PMID: 28620582 PMCID: PMC5449765 DOI: 10.3389/fcimb.2017.00190] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/02/2017] [Indexed: 11/13/2022] Open
Abstract
Bacterial obligate intracellular parasites are clinically significant animal and human pathogens. Central to the biology of these organisms is their level of adaptation to intracellular replication niches associated with physicochemical and nutritional constraints. While most bacterial pathogens can adapt to a wide range of environments, severe niche restriction-an inability to thrive in diverse environments-is a hallmark of bacterial obligate intracellular parasites. Herein the physicochemical and nutritional factors underlying the physiological basis for niche restriction in the zoonotic bacterial obligate intracellular parasite and Q fever agent Coxiella burnetii are characterized. Additionally, these factors are reviewed in the context of C. burnetii evolution and continued (patho) adaptation. C. burnetii replication was strictly dependent on a combination of moderately acidic pH, reduced oxygen tension, and presence of carbon dioxide. Of macronutrients, amino acids alone support replication under physicochemically favorable conditions. In addition to utilizing gluconeogenic substrates for replication, C. burnetii can also utilize glucose to generate biomass. A mutant with a disruption in the gene pckA, encoding phosphoenolpyruvate carboxykinase (PEPCK), the first committed step in gluconeogenesis, could be complemented chemically by the addition of glucose. Disruption of pckA resulted in a moderate glucose-dependent growth defect during infection of cultured host cells. Although, C. burnetii has the theoretical capacity to synthesize essential core metabolites via glycolysis and gluconeogenesis, amino acid auxotrophy essentially restricts C. burnetii replication to a niche providing ample access to amino acids. Overall, the described combination of physiochemical and nutritional growth requirements are strong indicators for why C. burnetii favors an acidified phagolysosome-derived vacuole in respiring tissue for replication.
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Affiliation(s)
| | | | | | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State UniversityPullman, WA, United States
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49
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van Schaik EJ, Case ED, Martinez E, Bonazzi M, Samuel JE. The SCID Mouse Model for Identifying Virulence Determinants in Coxiella burnetii. Front Cell Infect Microbiol 2017; 7:25. [PMID: 28217558 PMCID: PMC5289997 DOI: 10.3389/fcimb.2017.00025] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/19/2017] [Indexed: 01/09/2023] Open
Abstract
Coxiella burnetii is an intracellular, zoonotic pathogen that is the causative agent of Q fever. Infection most frequently occurs after inhalation of contaminated aerosols, which can lead to acute, self-limiting febrile illness or more serve chronic infections such as hepatitis or endocarditis. Macrophages are the principal target cells during infection where C. burnetii resides and replicates within a unique phagolysosome-like compartment, the Coxiella-containing vacuole (CCV). The first virulence determinant described as necessary for infection was full-length lipopolysaccarride (LPS); spontaneous rough mutants (phase II) arise after passage in immuno-incompetent hosts. Phase II C. burnetii are attenuated in immuno-competent animals, but are fully capable of infecting a variety of host cells in vitro. A clonal strain of the Nine Mile isolate (RSA439, clone 4), has a 26 KDa chromosomal deletion that includes LPS biosynthetic genes and is uniquely approved for use in BL2/ABL2 conditions. With the advances of axenic media and genetic tools for C. burnetii research, the characterization of novel virulence determinants is ongoing and almost exclusively performed using this attenuated clone. A major problem with predicting essential virulence loci with RSA439 is that, although some cell-autonomous phenotypes can be assessed in tissue culture, no animal model for assessing pathogenesis has been defined. Here we describe the use of SCID mice for predicting virulence factors of C. burnetii, in either independent or competitive infections. We propose that this model allows for the identification of mutations that are competent for intracellular replication in vitro, but attenuated for growth in vivo and predict essential innate immune responses modulated by the pathogen during infection as a central pathogenic strategy.
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Affiliation(s)
- Erin J. van Schaik
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
| | - Elizabeth D. Case
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
| | - Eric Martinez
- Centre National de la Recherche Scientifique, Formation de Recherche en Évolution 3689, Centre d'études d'agents Pathogènes et Biotechnologies Pour la Santé, Université MontpellierMontpellier, France
| | - Matteo Bonazzi
- Centre National de la Recherche Scientifique, Formation de Recherche en Évolution 3689, Centre d'études d'agents Pathogènes et Biotechnologies Pour la Santé, Université MontpellierMontpellier, France
| | - James E. Samuel
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
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