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Bontemps Z, Paranjape K, Guy L. Host-bacteria interactions: ecological and evolutionary insights from ancient, professional endosymbionts. FEMS Microbiol Rev 2024; 48:fuae021. [PMID: 39081075 PMCID: PMC11338181 DOI: 10.1093/femsre/fuae021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 07/22/2024] [Accepted: 07/29/2024] [Indexed: 08/23/2024] Open
Abstract
Interactions between eukaryotic hosts and their bacterial symbionts drive key ecological and evolutionary processes, from regulating ecosystems to the evolution of complex molecular machines and processes. Over time, endosymbionts generally evolve reduced genomes, and their relationship with their host tends to stabilize. However, host-bacteria relationships may be heavily influenced by environmental changes. Here, we review these effects on one of the most ancient and diverse endosymbiotic groups, formed by-among others-Legionellales, Francisellaceae, and Piscirickettsiaceae. This group is referred to as Deep-branching Intracellular Gammaproteobacteria (DIG), whose last common ancestor presumably emerged about 2 Ga ago. We show that DIGs are globally distributed, but generally at very low abundance, and are mainly identified in aquatic biomes. Most DIGs harbour a type IVB secretion system, critical for host-adaptation, but its structure and composition vary. Finally, we review the different types of microbial interactions that can occur in diverse environments, with direct or indirect effects on DIG populations. The increased use of omics technologies on environmental samples will allow a better understanding of host-bacterial interactions and help unravel the definition of DIGs as a group from an ecological, molecular, and evolutionary perspective.
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Affiliation(s)
- Zélia Bontemps
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75237 Uppsala, Sweden
| | - Kiran Paranjape
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75237 Uppsala, Sweden
| | - Lionel Guy
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75237 Uppsala, Sweden
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Köppen K, Fatykhova D, Holland G, Rauch J, Tappe D, Graff M, Rydzewski K, Hocke AC, Hippenstiel S, Heuner K. Ex vivo infection model for Francisella using human lung tissue. Front Cell Infect Microbiol 2023; 13:1224356. [PMID: 37492528 PMCID: PMC10365108 DOI: 10.3389/fcimb.2023.1224356] [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: 05/17/2023] [Accepted: 06/23/2023] [Indexed: 07/27/2023] Open
Abstract
Introduction Tularemia is mainly caused by Francisella tularensis (Ft) subsp. tularensis (Ftt) and Ft subsp. holarctica (Ftt) in humans and in more than 200 animal species including rabbits and hares. Human clinical manifestations depend on the route of infection and range from flu-like symptoms to severe pneumonia with a mortality rate up to 60% without treatment. So far, only 2D cell culture and animal models are used to study Francisella virulence, but the gained results are transferable to human infections only to a certain extent. Method In this study, we firstly established an ex vivo human lung tissue infection model using different Francisella strains: Ftt Life Vaccine Strain (LVS), Ftt LVS ΔiglC, Ftt human clinical isolate A-660 and a German environmental Francisella species strain W12-1067 (F-W12). Human lung tissue was used to determine the colony forming units and to detect infected cell types by using spectral immunofluorescence and electron microscopy. Chemokine and cytokine levels were measured in culture supernatants. Results Only LVS and A-660 were able to grow within the human lung explants, whereas LVS ΔiglC and F-W12 did not replicate. Using human lung tissue, we observed a greater increase of bacterial load per explant for patient isolate A-660 compared to LVS, whereas a similar replication of both strains was observed in cell culture models with human macrophages. Alveolar macrophages were mainly infected in human lung tissue, but Ftt was also sporadically detected within white blood cells. Although Ftt replicated within lung tissue, an overall low induction of pro-inflammatory cytokines and chemokines was observed. A-660-infected lung explants secreted slightly less of IL-1β, MCP-1, IP-10 and IL-6 compared to Ftt LVS-infected explants, suggesting a more repressed immune response for patient isolate A-660. When LVS and A-660 were used for simultaneous co-infections, only the ex vivo model reflected the less virulent phenotype of LVS, as it was outcompeted by A-660. Conclusion We successfully implemented an ex vivo infection model using human lung tissue for Francisella. The model delivers considerable advantages and is able to discriminate virulent Francisella from less- or non-virulent strains and can be used to investigate the role of specific virulence factors.
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Affiliation(s)
- Kristin Köppen
- Working group “Cellular Interactions of Bacterial Pathogens”, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Diana Fatykhova
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gudrun Holland
- Advanced Light and Electron Microscopy, ZBS 4, Robert Koch Institute, Berlin, Germany
| | - Jessica Rauch
- Research Group Zoonoses, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Dennis Tappe
- Research Group Zoonoses, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Mareike Graff
- Department for General and Thoracic Surgery, DRK Clinics, Berlin, Germany
| | - Kerstin Rydzewski
- Working group “Cellular Interactions of Bacterial Pathogens”, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Andreas C. Hocke
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Stefan Hippenstiel
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Klaus Heuner
- Working group “Cellular Interactions of Bacterial Pathogens”, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
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Köppen K, Rydzewski K, Doellinger J, Myrtennäs K, Forsman M, Appelt S, Scholz H, Heuner K. Phenotypic and genotypic discrimination of Francisella tularensis ssp. holarctica clades. Int J Med Microbiol 2023; 313:151583. [PMID: 37331050 DOI: 10.1016/j.ijmm.2023.151583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/20/2023] Open
Abstract
Francisella tularensis is the causative agent of tularemia, a zoonotic disease with a wide host range. F. tularensis ssp. holarctica (Fth) is of clinical relevance for European countries, including Germany. Whole genome sequencing methods, including canonical Single Nucleotide Polymorphism (canSNP) typing and whole genome SNP typing, have revealed that European Fth strains belong to a few monophyletic populations. The majority of German Fth isolates belong to two basal phylogenetic clades B.6 (biovar I) and B.12 (biovar II). Strains of B.6 and B.12 seem to differ in their pathogenicity, and it has been shown that strains of biovar II are resistant against erythromycin. In this study, we present data corroborating our previous data demonstrating that basal clade B.12 can be divided into clades B.71 and B.72. By applying phylogenetic whole genome analysis as well as proteome analysis, we could verify that strains of these two clades are distinct from one another. This was confirmed by measuring the intensity of backscatter light on bacteria grown in liquid media. Strains belonging to clades B.6, B.71 or B.72 showed clade-specific backscatter growth curves. Furthermore, we present the whole genome sequence of strain A-1341, as a reference genome of clade B.71, and whole proteomes comparison of Fth strains belonging to clades B.6, B.71 and B.72. Further research is necessary to investigate phenotypes and putative differences in pathogenicity of the investigated different clades of Fth to better understand the relationship between observed phenotypes, pathogenicity and distribution of Fth strains.
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Affiliation(s)
- Kristin Köppen
- Working group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Kerstin Rydzewski
- Working group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Joerg Doellinger
- Centre for Biological Threats and Special Pathogens, Proteomics and Spectroscopy (ZBS 6), Robert Koch Institute, Berlin, Germany
| | - Kerstin Myrtennäs
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Umeå, Sweden
| | - Mats Forsman
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Umeå, Sweden
| | - Sandra Appelt
- Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Holger Scholz
- Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Klaus Heuner
- Working group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany; Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany.
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Borgschulte HS, Jacob D, Zeeh J, Scholz HC, Heuner K. Ulceroglandular form of tularemia after squirrel bite: a case report. J Med Case Rep 2022; 16:309. [PMID: 35974355 PMCID: PMC9381146 DOI: 10.1186/s13256-022-03510-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/27/2022] [Indexed: 11/18/2022] Open
Abstract
Background The diagnosis of tularemia is not often considered in Germany as the disease is still rare in this country. Nonetheless, Francisella tularensis, the causative agent of tularemia, can infect numerous animal species and should, therefore, not be neglected as a dangerous pathogen. Tularemia can lead to massively swollen lymph nodes and might even be fatal without antibiotic treatment. To our knowledge, the case described here is the first report of the disease caused by a squirrel bite in Germany. Case presentation A 59-year-old German woman with a past medical history of hypothyroidism and cutaneous lupus erythematosus presented at the emergency room at St. Katharinen Hospital with ongoing symptoms and a swollen right elbow persisting despite antibiotic therapy with cefuroxime for 7 days after she had been bitten (right hand) by a wild squirrel (Eurasian red squirrel). After another 7 days of therapy with piperacillin/tazobactam, laboratory analysis using real-time polymerase chain reaction (PCR) confirmed the suspected diagnosis of tularemia on day 14. After starting the recommended antibiotic treatment with ciprofloxacin, the patient recovered rapidly. Conclusion This is the first report of a case of tularemia caused by a squirrel bite in Germany. A naturally infected squirrel has recently been reported in Switzerland for the first time. The number of human cases of tularemia has been increasing over the last years and, therefore, tularemia should be taken into consideration as a diagnosis, especially in a patient bitten by an animal who also presents with headache, increasing pain, lymphadenitis, and fever, as well as impaired wound healing. The pathogen can easily be identified by a specific real-time PCR assay of wound swabs and/or by antibody detection, for example by enzyme-linked immunosorbent assay (ELISA), if the incident dates back longer than 2 weeks.
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Affiliation(s)
- Hannah Sophia Borgschulte
- Department of Internal Medicine 2, St. Katharinen-Hospital, Kapellenstr. 1-5, 50226, Frechen, Germany
| | - Daniela Jacob
- Division of Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353, Berlin, Germany
| | - Jörg Zeeh
- Department of Internal Medicine 2, St. Katharinen-Hospital, Kapellenstr. 1-5, 50226, Frechen, Germany
| | - Holger C Scholz
- Division of Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353, Berlin, Germany
| | - Klaus Heuner
- Division of Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353, Berlin, Germany.
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Śliwka P, Ochocka M, Skaradzińska A. Applications of bacteriophages against intracellular bacteria. Crit Rev Microbiol 2021; 48:222-239. [PMID: 34428105 DOI: 10.1080/1040841x.2021.1960481] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Infectious diseases pose a significant threat to both human and animal populations. Intracellular bacteria are a group of pathogens that invade and survive within the interior of eukaryotic cells, which in turn protect them from antibacterial drugs and the host immune system. Limited penetration of antibacterials into host cells results in insufficient bacterial clearance and treatment failure. Bacteriophages have, over the decades, been proved to play an important role in combating bacterial infections (phage therapy), making them an important alternative to classical antibiotic strategies today. Phages have been found to be effective at killing various species of extracellular bacteria, but little is still known about how phages control intracellular infections. With advances in phage genomics and mechanisms of delivery and cell uptake, the development of phage-based antibacterial strategies to address the treatment of intracellular bacteria has general potential. In this review, we present the current state of knowledge regarding the application of bacteriophages against intracellular bacteria. We cover phage deployment against the most common intracellular pathogens with special attention to therapeutic and preventive strategies.
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Affiliation(s)
- Paulina Śliwka
- Department of Biotechnology and Food Microbiology, Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Marta Ochocka
- Department of Biotechnology and Food Microbiology, Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Aneta Skaradzińska
- Department of Biotechnology and Food Microbiology, Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
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Kassinger SJ, van Hoek ML. Genetic Determinants of Antibiotic Resistance in Francisella. Front Microbiol 2021; 12:644855. [PMID: 34054749 PMCID: PMC8149597 DOI: 10.3389/fmicb.2021.644855] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/25/2021] [Indexed: 12/21/2022] Open
Abstract
Tularemia, caused by Francisella tularensis, is endemic to the northern hemisphere. This zoonotic organism has historically been developed into a biological weapon. For this Tier 1, Category A select agent, it is important to expand our understanding of its mechanisms of antibiotic resistance (AMR). Francisella is unlike many Gram-negative organisms in that it does not have significant plasmid mobility, and does not express AMR mechanisms on plasmids; thus plasmid-mediated resistance does not occur naturally. It is possible to artificially introduce plasmids with AMR markers for cloning and gene expression purposes. In this review, we survey both the experimental research on AMR in Francisella and bioinformatic databases which contain genomic and proteomic data. We explore both the genetic determinants of intrinsic AMR and naturally acquired or engineered antimicrobial resistance as well as phenotypic resistance in Francisella. Herein we survey resistance to beta-lactams, monobactams, carbapenems, aminoglycosides, tetracycline, polymyxins, macrolides, rifampin, fosmidomycin, and fluoroquinolones. We also highlight research about the phenotypic AMR difference between planktonic and biofilm Francisella. We discuss newly developed methods of testing antibiotics against Francisella which involve the intracellular nature of Francisella infection and may better reflect the eventual clinical outcomes for new antibiotic compounds. Understanding the genetically encoded determinants of AMR in Francisella is key to optimizing the treatment of patients and potentially developing new antimicrobials for this dangerous intracellular pathogen.
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Affiliation(s)
| | - Monique L. van Hoek
- School of Systems Biology, George Mason University, Manassas, VA, United States
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First Description of a Temperate Bacteriophage (vB _FhiM_KIRK) of Francisella hispaniensis Strain 3523. Viruses 2021; 13:v13020327. [PMID: 33672748 PMCID: PMC7924643 DOI: 10.3390/v13020327] [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: 02/03/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 12/31/2022] Open
Abstract
Here we present the characterization of a Francisella bacteriophage (vB_FhiM_KIRK) including the morphology, the genome sequence and the induction of the prophage. The prophage sequence (FhaGI-1) has previously been identified in F. hispaniensis strain 3523. UV radiation induced the prophage to assemble phage particles consisting of an icosahedral head (~52 nm in diameter), a tail of up to 97 nm in length and a mean width of 9 nm. The double stranded genome of vB_FhiM_KIRK contains 51 open reading frames and is 34,259 bp in length. The genotypic and phylogenetic analysis indicated that this phage seems to belong to the Myoviridae family of bacteriophages. Under the conditions tested here, host cell (Francisella hispaniensis 3523) lysis activity of KIRK was very low, and the phage particles seem to be defective for infecting new bacterial cells. Nevertheless, recombinant KIRK DNA was able to integrate site-specifically into the genome of different Francisella species after DNA transformation.
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Appelt S, Faber M, Köppen K, Jacob D, Grunow R, Heuner K. Francisella tularensis Subspecies holarctica and Tularemia in Germany. Microorganisms 2020; 8:microorganisms8091448. [PMID: 32971773 PMCID: PMC7564102 DOI: 10.3390/microorganisms8091448] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 12/26/2022] Open
Abstract
Tularemia is a zoonotic disease caused by Francisella tularensis a small, pleomorphic, facultative intracellular bacterium. In Europe, infections in animals and humans are caused mainly by Francisella tularensis subspecies holarctica. Humans can be exposed to the pathogen directly and indirectly through contact with sick animals, carcasses, mosquitoes and ticks, environmental sources such as contaminated water or soil, and food. So far, F. tularensis subsp. holarctica is the only Francisella species known to cause tularemia in Germany. On the basis of surveillance data, outbreak investigations, and literature, we review herein the epidemiological situation-noteworthy clinical cases next to genetic diversity of F. tularensis subsp. holarctica strains isolated from patients. In the last 15 years, the yearly number of notified cases of tularemia has increased steadily in Germany, suggesting that the disease is re-emerging. By sequencing F. tularensis subsp. holarctica genomes, knowledge has been added to recent findings, completing the picture of genotypic diversity and geographical segregation of Francisella clades in Germany. Here, we also shortly summarize the current knowledge about a new Francisella species (Francisella sp. strain W12-1067) that has been recently identified in Germany. This species is the second Francisella species discovered in Germany.
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Affiliation(s)
- Sandra Appelt
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, 13353 Berlin, Germany; (S.A.); (D.J.); (R.G.)
| | - Mirko Faber
- Gastrointestinal Infections, Zoonoses and Tropical Infections (Division 35), Department for Infectious Disease Epidemiology, Robert Koch Institute, 13353 Berlin, Germany;
| | - Kristin Köppen
- Cellular Interactions of Bacterial Pathogens, ZBS 2, Robert Koch Institute, 13353 Berlin, Germany;
| | - Daniela Jacob
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, 13353 Berlin, Germany; (S.A.); (D.J.); (R.G.)
| | - Roland Grunow
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, 13353 Berlin, Germany; (S.A.); (D.J.); (R.G.)
| | - Klaus Heuner
- Cellular Interactions of Bacterial Pathogens, ZBS 2, Robert Koch Institute, 13353 Berlin, Germany;
- Correspondence: ; Tel.: +49-301-8754-2226
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Chen F, Köppen K, Rydzewski K, Einenkel R, Morguet C, Vu DT, Eisenreich W, Heuner K. Myo-Inositol as a carbon substrate in Francisella and insights into the metabolism of Francisella sp. strain W12-1067. Int J Med Microbiol 2020; 310:151426. [PMID: 32444321 DOI: 10.1016/j.ijmm.2020.151426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 04/06/2020] [Accepted: 04/29/2020] [Indexed: 12/29/2022] Open
Abstract
Recently, a new environmental Francisella strain, Francisella sp. strain W12-1067, has been identified in Germany. This strain is negative for the Francisella pathogenicity island (FPI) but exhibits a putative alternative type VI secretion system. Some known virulence factors of Francisella are present, but the pathogenic capacity of this species is not known yet. In silico genome analysis reveals the presence of a gene cluster tentatively enabling myo-inositol (MI) utilization via a putative inositol oxygenase. Labelling experiments starting from 2H-inositol demonstrate that this gene cluster is indeed involved in the metabolism of MI. We further show that, under in vitro conditions, supply of MI increases growth rates of strain W12-1067 in the absence of glucose and that the metabolism of MI is strongly reduced in a W12-1067 mutant lacking the MI gene cluster. The positive growth effect of MI in the absence of glucose is restored in this mutant strain by introducing the complete MI gene cluster. F. novicida Fx1 is also positive for the MI metabolizing gene cluster and MI again increases growth in a glucose-free medium, in contrast to F. novicida strain U112, which is shown to be a natural mutant of the MI metabolizing gene cluster. Labelling experiments of Francisella sp. strain W12-1067 in medium T containing 13C-glucose, 13C-serine or 13C-glycerol as tracers suggest a bipartite metabolism where glucose is mainly metabolized through glycolysis, but not through the Entner-Doudoroff pathway or the pentose phosphate pathway. Carbon flux from 13C-glycerol and 13C-serine is less active, and label from these tracers is transferred mostly into amino acids, lactate and fatty acids. Together, the metabolism of Francisella sp. strain W12-1067 seems to be more related to the respective one in F. novicida rather than in F. tularensis subsp. holarctica.
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Affiliation(s)
- Fan Chen
- Department of Chemistry, Chair of Biochemistry, Technische Universität München, Garching, Germany
| | - Kristin Köppen
- Working Group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, ZBS 2, Robert Koch Institute, Berlin, Germany
| | - Kerstin Rydzewski
- Working Group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, ZBS 2, Robert Koch Institute, Berlin, Germany
| | - Rosa Einenkel
- Working Group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, ZBS 2, Robert Koch Institute, Berlin, Germany
| | - Clara Morguet
- Department of Chemistry, Chair of Biochemistry, Technische Universität München, Garching, Germany
| | - Duc Tung Vu
- Department of Chemistry, Chair of Biochemistry, Technische Universität München, Garching, Germany
| | - Wolfgang Eisenreich
- Department of Chemistry, Chair of Biochemistry, Technische Universität München, Garching, Germany.
| | - Klaus Heuner
- Working Group: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, ZBS 2, Robert Koch Institute, Berlin, Germany.
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Screen for fitness and virulence factors of Francisella sp. strain W12-1067 using amoebae. Int J Med Microbiol 2019; 309:151341. [PMID: 31451389 DOI: 10.1016/j.ijmm.2019.151341] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/17/2019] [Accepted: 08/18/2019] [Indexed: 11/21/2022] Open
Abstract
Francisella tularensis is the causative agent of the human disease referred to as tularemia. Other Francisella species are known but less is understood about their virulence factors. The role of environmental amoebae in the life-cycle of Francisella is still under discussion. Francisella sp. strain W12-1067 (F-W12) is an environmental Francisella isolate recently identified in Germany which is negative for the Francisella pathogenicity island, but exhibits a putative alternative type VI secretion system. Putative virulence factors have been identified in silico in the genome of F-W12. In this work, we established a "scatter screen", used earlier for pathogenic Legionella, to verify experimentally and identify candidate fitness factors using a transposon mutant bank of F-W12 and Acanthamoeba lenticulata as host organism. In these experiments, we identified 79 scatter clones (amoeba sensitive), which were further analyzed by an infection assay identifying 9 known virulence factors, but also candidate fitness factors of F-W12 not yet described as fitness factors in Francisella. The majority of the identified genes encoded proteins involved in the synthesis or maintenance of the cell envelope (LPS, outer membrane, capsule) or in the metabolism (glycolysis, gluconeogenesis, pentose phosphate pathway). Further 13C-flux analysis of the Tn5 glucokinase mutant strain revealed that the identified gene indeed encodes the sole active glucokinase in F-W12. In conclusion, candidate fitness factors of the new Francisella species F-W12 were identified using the scatter screen method which might also be usable for other Francisella species.
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