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Graham CI, MacMartin TL, de Kievit TR, Brassinga AKC. Molecular regulation of virulence in Legionella pneumophila. Mol Microbiol 2024; 121:167-195. [PMID: 37908155 DOI: 10.1111/mmi.15172] [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: 05/31/2023] [Revised: 09/15/2023] [Accepted: 09/17/2023] [Indexed: 11/02/2023]
Abstract
Legionella pneumophila is a gram-negative bacteria found in natural and anthropogenic aquatic environments such as evaporative cooling towers, where it reproduces as an intracellular parasite of cohabiting protozoa. If L. pneumophila is aerosolized and inhaled by a susceptible person, bacteria may colonize their alveolar macrophages causing the opportunistic pneumonia Legionnaires' disease. L. pneumophila utilizes an elaborate regulatory network to control virulence processes such as the Dot/Icm Type IV secretion system and effector repertoire, responding to changing nutritional cues as their host becomes depleted. The bacteria subsequently differentiate to a transmissive state that can survive in the environment until a replacement host is encountered and colonized. In this review, we discuss the lifecycle of L. pneumophila and the molecular regulatory network that senses nutritional depletion via the stringent response, a link to stationary phase-like metabolic changes via alternative sigma factors, and two-component systems that are homologous to stress sensors in other pathogens, to regulate differentiation between the intracellular replicative phase and more transmissible states. Together, we highlight how this prototypic intracellular pathogen offers enormous potential in understanding how molecular mechanisms enable intracellular parasitism and pathogenicity.
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Affiliation(s)
- Christopher I Graham
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Teassa L MacMartin
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Teresa R de Kievit
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Ann Karen C Brassinga
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
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2
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Hoque MM, Espinoza-Vergara G, McDougald D. Protozoan predation as a driver of diversity and virulence in bacterial biofilms. FEMS Microbiol Rev 2023; 47:fuad040. [PMID: 37458768 DOI: 10.1093/femsre/fuad040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/19/2023] [Accepted: 07/07/2023] [Indexed: 07/27/2023] Open
Abstract
Protozoa are eukaryotic organisms that play a crucial role in nutrient cycling and maintaining balance in the food web. Predation, symbiosis and parasitism are three types of interactions between protozoa and bacteria. However, not all bacterial species are equally susceptible to protozoan predation as many are capable of defending against predation in numerous ways and may even establish either a symbiotic or parasitic life-style. Biofilm formation is one such mechanism by which bacteria can survive predation. Structural and chemical components of biofilms enhance resistance to predation compared to their planktonic counterparts. Predation on biofilms gives rise to phenotypic and genetic heterogeneity in prey that leads to trade-offs in virulence in other eukaryotes. Recent advances, using molecular and genomics techniques, allow us to generate new information about the interactions of protozoa and biofilms of prey bacteria. This review presents the current state of the field on impacts of protozoan predation on biofilms. We provide an overview of newly gathered insights into (i) molecular mechanisms of predation resistance in biofilms, (ii) phenotypic and genetic diversification of prey bacteria, and (iii) evolution of virulence as a consequence of protozoan predation on biofilms.
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Affiliation(s)
- M Mozammel Hoque
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Gustavo Espinoza-Vergara
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Diane McDougald
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
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3
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Ashbolt NJ. Conceptual model to inform Legionella-amoebae control, including the roles of extracellular vesicles in engineered water system infections. Front Cell Infect Microbiol 2023; 13:1200478. [PMID: 37274310 PMCID: PMC10232903 DOI: 10.3389/fcimb.2023.1200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/08/2023] [Indexed: 06/06/2023] Open
Abstract
Extracellular vesicles (EVs or exosomes) are well described for bacterial pathogens associated with our gastrointestinal system, and more recently as a novel mechanism for environmental persistence, dissemination and infection for human enteric viruses. However, the roles played by EVs in the ancient arms race that continues between amoebae and one of their prey, Legionella pneumophila, is poorly understood. At best we know of intracellular vesicles of amoebae containing a mix of bacterial prey species, which also provides an enhanced niche for bacteriophage infection/spread. Free-living amoeba-associated pathogens have recently been recognized to have enhanced resistance to disinfection and environmental stressors, adding to previously understood (but for relatively few species of) bacteria sequestered within amoebal cysts. However, the focus of the current work is to review the likely impacts of large numbers of respiratory-sized EVs containing numerous L. pneumophila cells studied in pure and biofilm systems with mixed prey species. These encapsulated pathogens are orders of magnitude more resistant to disinfection than free cells, and our engineered systems with residual disinfectants could promote evolution of resistance (including AMR), enhanced virulence and EV release. All these are key features for evolution within a dead-end human pathogen post lung infection. Traditional single-hit pathogen infection models used to estimate the probability of infection/disease and critical environmental concentrations via quantitative microbial risk assessments may also need to change. In short, recognizing that EV-packaged cells are highly virulent units for transmission of legionellae, which may also modulate/avoid human host immune responses. Key data gaps are raised and a previous conceptual model expanded upon to clarify where biofilm EVs could play a role promoting risk as well as inform a more wholistic management program to proactively control legionellosis.
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4
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Paquet VE, Durocher AF, Charette SJ. Aeromonas salmonicida intra-species divergence revealed by the various strategies displayed when grazed by Tetrahymena pyriformis. FEMS Microbiol Lett 2022; 369:6650351. [PMID: 35883218 DOI: 10.1093/femsle/fnac067] [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: 02/11/2022] [Revised: 05/31/2022] [Accepted: 07/23/2022] [Indexed: 11/13/2022] Open
Abstract
Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this species, the number of characterized mesophilic strains is increasing. Thus, this species may serve as a model for the study of intraspecies lifestyle diversity. Although bacteria are preyed upon by protozoan predators, their interaction inside or outside the phagocytic pathway of the predator can provide several advantages to the bacteria. To correlate intraspecies diversity with predation outcome, we studied the fate of psychrophilic and mesophilic strains of A. salmonicida co-cultured with the ciliate Tetrahymena pyriformis. Three types of outcome were observed: digestion, resistance to phagocytosis and pathogenicity. The psychrophilic strains are fully digested by the ciliate. In contrast, the mesophilic A. salmonicida subsp. pectinolytica strain is pathogenic to the ciliate. All the other mesophilic strains display mechanisms to resist phagocytosis and/or digestion, which allow them to survive ciliate predation. In some cases, passage through the phagocytic pathway resulted in a few mesophilic A. salmonicida being packaged inside fecal pellets. This study sheds light on the great phenotypic diversity observed in the complex range of mechanisms used by A. salmonicida to confront a predator.
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Affiliation(s)
- Valérie E Paquet
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
| | - Alicia F Durocher
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
| | - Steve J Charette
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
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5
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Acrylate protects a marine bacterium from grazing by a ciliate predator. Nat Microbiol 2021; 6:1351-1356. [PMID: 34697458 DOI: 10.1038/s41564-021-00981-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 09/16/2021] [Indexed: 12/26/2022]
Abstract
Cleavage of dimethylsulfoniopropionate (DMSP) can deter herbivores in DMSP-producing eukaryotic algae; however, it is unclear whether a parallel defence mechanism operates in marine bacteria. Here we demonstrate that the marine bacterium Puniceibacterium antarcticum SM1211, which does not use DMSP as a carbon source, has a membrane-associated DMSP lyase, DddL. At high concentrations of DMSP, DddL causes an accumulation of acrylate around cells through the degradation of DMSP, which protects against predation by the marine ciliate Uronema marinum. The presence of acrylate can alter the grazing preference of U. marinum to other bacteria in the community, thereby influencing community structure.
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Kawashiro A, Okubo T, Nakamura S, Thapa J, Miyake M, Yamaguchi H. Wild ciliates differ in susceptibility to Legionella pneumophila JR32. MICROBIOLOGY-SGM 2021; 167. [PMID: 34402779 DOI: 10.1099/mic.0.001078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated how Legionella pneumophila (Lp) JR32 interacts with Anteglaucoma CS11A and Colpoda E6, two ciliates that we isolated from sewage and sink trap sludge, respectively, using a handmade maze device containing a 96-well crafting plate. Our 18S rDNA-based phylogenetic analysis showed that Anteglaucoma CS11A and Colpoda E6 formed distinct clades. Scanning electron microscopy showed that Anteglaucoma CS11A had a bigger-sized body than Colpoda E6 and, unlike Tetrahymena IB (the reference strain), neither ciliate produced pellets, which are extracellular vacuoles. Fluorescence microscopic observations revealed that although the intake amounts differed, all three ciliates rapidly ingested LpJR32 regardless of the presence or absence of the icm/dot virulence genes, indicating that they all interacted with LpJR32. In co-cultures with Anteglaucoma CS11A, the LpJR32 levels were maintained but fell dramatically when the co-culture contained the LpJR32 icm/dot deletion mutant instead. Anteglaucoma CS11A died within 2 days of co-culture with LpJR32, but survived co-culture with the deletion mutant. In co-cultures with Colpoda E6, LpJR32 levels were maintained but temporarily decreased independently of the virulence gene. Concurrently, the Colpoda E6 ciliates survived by forming cysts, which may enable them to resist harsh environments, and by diminishing the sensitivity of trophozoites to Lp. In the Tetrahymena IB co-cultures with LpJR32 or Δicm/dot, the Lp levels were maintained, albeit with temporal decreases, and the Tetrahymena IB levels were also maintained. We conclude that unlike Tetrahymena IB with pellet production, Anteglaucoma CS11A can be killed by LpJR32 infection, and Colpoda E6 can resist LpJR32 infection through cyst formation and the low sensitivity of trophozoites to Lp. Thus, the two ciliates that we isolated had different susceptibilities to LpJR32 infection.
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Affiliation(s)
- Airi Kawashiro
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Torahiko Okubo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Jeewan Thapa
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.,Division of Bioresources Research Center for Zoonosis Control, Hokkaido University, Hokkaido, Sapporo, Japan
| | - Masaki Miyake
- Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
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7
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Paniagua AT, Paranjape K, Hu M, Bédard E, Faucher SP. Impact of temperature on Legionella pneumophila, its protozoan host cells, and the microbial diversity of the biofilm community of a pilot cooling tower. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 712:136131. [PMID: 31931228 DOI: 10.1016/j.scitotenv.2019.136131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/13/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Legionella pneumophila is a waterborne bacterium known for causing Legionnaires' Disease, a severe pneumonia. Cooling towers are a major source of outbreaks, since they provide ideal conditions for L. pneumophila growth and produce aerosols. In such systems, L. pneumophila typically grow inside protozoan hosts. Several abiotic factors such as water temperature, pipe material and disinfection regime affect the colonization of cooling towers by L. pneumophila. The local physical and biological factors promoting the growth of L. pneumophila in water systems and its spatial distribution are not well understood. Therefore, we built a lab-scale cooling tower to study the dynamics of L. pneumophila colonization in relationship to the resident microbiota and spatial distribution. The pilot was filled with water from an operating cooling tower harboring low levels of L. pneumophila. It was seeded with Vermamoeba vermiformis, a natural host of L. pneumophila, and then inoculated with L. pneumophila. After 92 days of operation, the pilot was disassembled, the water was collected, and biofilm was extracted from the pipes. The microbiome was studied using 16S rRNA and 18S rRNA genes amplicon sequencing. The communities of the water and of the biofilm were highly dissimilar. The relative abundance of Legionella in water samples reached up to 11% whereas abundance in the biofilm was extremely low (≤0.5%). In contrast, the host cells were mainly present in the biofilm. This suggests that L. pneumophila grows in host cells associated with biofilm and is then released back into the water following host cell lysis. In addition, water temperature shaped the bacterial and eukaryotic community of the biofilm, indicating that different parts of the systems may have different effects on Legionella growth.
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Affiliation(s)
- Adriana Torres Paniagua
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Kiran Paranjape
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Mengqi Hu
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada
| | - Emilie Bédard
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada; Department of Civil Engineering, Polytechnique Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7, Canada.
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Drive, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
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8
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Matsushita M, Okubo T, Hasegawa T, Matsuo J, Watanabe T, Iwasaki S, Fukumoto T, Hayasaka K, Akizawa K, Shimizu C, Yamaguchi H. Tetrahymena promotes interactive transfer of carbapenemase gene encoded in plasmid between fecal Escherichia coli and environmental Aeromonas caviae. Microbiol Immunol 2019; 62:720-728. [PMID: 30357893 DOI: 10.1111/1348-0421.12656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 10/01/2018] [Accepted: 10/22/2018] [Indexed: 01/06/2023]
Abstract
Tetrahymena can facilitate plasmid transfer among Escherichia coli or from E. coli to Salmonella Enteritidis via vesicle accumulation. In this study, whether ciliates promote the interactive transfer of plasmids encoding blaIMP-1 between fecal E. coli and environmental Aeromonas caviae was investigated. Both bacteria were mixed with or without ciliates and incubated overnight at 30°C. The frequency of plasmid-acquired bacteria was estimated by colony counts using an agar plate containing ceftazidim (CAZ) followed by determination of the minimum inhibitory concentration (MIC). Cultures containing ciliates interactively transferred the plasmid between E. coli and Aeromonas with a frequency of 10-4 to 10-5 . All plasmid-acquired bacteria showed a MIC against CAZ of >128 μg/mL and the plasmid transfer was confirmed by PCR amplification of the blaIMP-1 gene. Fluorescent observation showed that both bacteria accumulated in the same vesicle and that transwell sequestering significantly decreased the transfer frequency. Although ciliates preferentially ingested E. coli rather than A. caviae, both bacteria were co-localized into the same vesicles of ciliates, indicating that their meeting is associated with the gene transfer. Thus, ciliates interactively promote plasmid transfer between E. coli and A. caviae. The results of this study will facilitate control of the spread of multiple-antibiotic resistant bacteria.
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Affiliation(s)
- Mizue Matsushita
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Torahiko Okubo
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Takaki Hasegawa
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Junji Matsuo
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Takanori Watanabe
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Sumio Iwasaki
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Tatsuya Fukumoto
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Kasumi Hayasaka
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Kozi Akizawa
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Chikara Shimizu
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Hiroyuki Yamaguchi
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
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9
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Boamah DK, Zhou G, Ensminger AW, O'Connor TJ. From Many Hosts, One Accidental Pathogen: The Diverse Protozoan Hosts of Legionella. Front Cell Infect Microbiol 2017; 7:477. [PMID: 29250488 PMCID: PMC5714891 DOI: 10.3389/fcimb.2017.00477] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/31/2017] [Indexed: 01/03/2023] Open
Abstract
The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen Legionella pneumophila. Given their impact on human health, Legionella species and the mechanisms responsible for their replication within host cells are often studied in alveolar macrophages, the primary human cell type associated with disease. Despite the potential severity of individual cases of disease, Legionella are not spread from person-to-person. Thus, from the pathogen's perspective, interactions with human cells are accidents of time and space—evolutionary dead ends with no impact on Legionella's long-term survival or pathogenic trajectory. To understand Legionella as a pathogen is to understand its interaction with its natural hosts: the polyphyletic protozoa, a group of unicellular eukaryotes with a staggering amount of evolutionary diversity. While much remains to be understood about these enigmatic hosts, we summarize the current state of knowledge concerning Legionella's natural host range, the diversity of Legionella-protozoa interactions, the factors influencing these interactions, the importance of avoiding the generalization of protozoan-bacterial interactions based on a limited number of model hosts and the central role of protozoa to the biology, evolution, and persistence of Legionella in the environment.
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Affiliation(s)
- David K Boamah
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Guangqi Zhou
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Alexander W Ensminger
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Public Health Ontario, Toronto, ON, Canada
| | - Tamara J O'Connor
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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10
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Pang M, Lin X, Liu J, Guo C, Gao S, Du H, Lu C, Liu Y. Identification of Aeromonas hydrophila Genes Preferentially Expressed after Phagocytosis by Tetrahymena and Involvement of Methionine Sulfoxide Reductases. Front Cell Infect Microbiol 2016; 6:199. [PMID: 28083518 PMCID: PMC5183988 DOI: 10.3389/fcimb.2016.00199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 12/13/2016] [Indexed: 01/03/2023] Open
Abstract
Free-living protozoa affect the survival and virulence evolution of pathogens in the environment. In this study, we explored the fate of Aeromonas hydrophila when co-cultured with the bacteriovorous ciliate Tetrahymena thermophila and investigated bacterial gene expression associated with the co-culture. Virulent A. hydrophila strains were found to have ability to evade digestion in the vacuoles of this protozoan. In A. hydrophila, a total of 116 genes were identified as up-regulated following co-culture with T. thermophila by selective capture of transcribed sequences (SCOTS) and comparative dot-blot analysis. A large proportion of these genes (42/116) play a role in metabolism, and some of the genes have previously been characterized as required for bacterial survival and replication within macrophages. Then, we inactivated the genes encoding methionine sulfoxide reductases, msrA, and msrB, in A. hydrophila. Compared to the wild-type, the mutants ΔmsrA and ΔmsrAB displayed significantly reduced resistance to predation by T. thermophila, and 50% lethal dose (LD50) determinations in zebrafish demonstrated that both mutants were highly attenuated. This study forms a solid foundation for the study of mechanisms and implications of bacterial defenses.
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Affiliation(s)
- Maoda Pang
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China; Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Food Safety, Jiangsu Academy of Agricultural SciencesNanjing, China
| | - Xiaoqin Lin
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Jin Liu
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Changming Guo
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Shanshan Gao
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Hechao Du
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Chengping Lu
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Yongjie Liu
- Department of Preventive Veterinary, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
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11
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Oguri S, Hanawa T, Matsuo J, Ishida K, Yamazaki T, Nakamura S, Okubo T, Fukumoto T, Akizawa K, Shimizu C, Kamiya S, Yamaguchi H. Protozoal ciliate promotes bacterial autoinducer-2 accumulation in mixed culture with Escherichia coli. J GEN APPL MICROBIOL 2016; 61:203-10. [PMID: 26582290 DOI: 10.2323/jgam.61.203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We have previously demonstrated conjugation of Escherichia coli into vacuoles of the protozoal ciliate (Tetrahymena thermophila). This indicated a possible role of ciliates in evoking bacterial quorum sensing, directly connecting bacterial survival via accumulation in the ciliate vacuoles. We therefore assessed if ciliates promoted bacterial autoinducer (AI)-2 accumulation with vacuole formation, which controls quorum sensing. E. coli AI-2 accumulation was significantly enhanced in the supernatants of a mixed culture of ciliates and bacteria, likely depending on ciliate density rather than bacterial concentration. As expected, AI-2 production was significantly correlated with vacuole formation. The experiment with E. coli luxS mutants showed that ciliates failed to enhance bacterial AI-2 accumulation, denying a nonspecific phenomenon. Fluorescence microscopy revealed accumulation of fragmented bacteria in ciliate vacuoles, and, more importantly, expulsion of the vacuoles containing disrupted bacteria into the culture supernatant. There was no increase in the expression of luxS (encoding AI-2) or ydgG (a transporter for controlling bacterial export of AI-2). We conclude that ciliates promote bacterial AI-2 accumulation in a mixed culture, via accumulation of disrupted bacteria in ciliate vacuoles followed by expulsion of the vacuoles, independently of luxS or ydgG gene induction. This is believed to be the first demonstration of a relationship between E. coli AI-2 dynamics and ciliates. In the natural environment, ciliate biotopes may provide a survival advantage to bacteria inhabiting such biotopes, via evoking quorum sensing.
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12
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Draft Genome Sequences of Legionella pneumophila JR32 and Lp01 Laboratory Strains Domesticated in Japan. GENOME ANNOUNCEMENTS 2016; 4:4/4/e00791-16. [PMID: 27491976 PMCID: PMC4974328 DOI: 10.1128/genomea.00791-16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report here the draft genome sequences of two Legionella pneumophila variant strains (JR32 and Lp01_666) originally derived from a Philadelphia-1 clinical isolate, domesticated in Japan, with distinct susceptibility to amoebae. Detailed genomic analysis will allow us to better understand Legionella adaptation and survival mechanisms in host cells.
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13
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Kusić D, Ramoji A, Neugebauer U, Rösch P, Popp J. Raman Spectroscopic Characterization of Packaged L. pneumophila Strains Expelled by T. thermophila. Anal Chem 2016; 88:2533-7. [DOI: 10.1021/acs.analchem.5b04699] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Dragana Kusić
- Institut
für Physikalische Chemie and Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, D-07743 Jena, Germany
| | - Anuradha Ramoji
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, D-07745 Jena, Germany
- Center
for Sepsis Control and Care (CSCC), Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
| | - Ute Neugebauer
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, D-07745 Jena, Germany
- Center
for Sepsis Control and Care (CSCC), Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
- InfectoGnostics Forschungscampus Jena e.V., Zentrum für
Angewandte Forschung, Philosophenweg 7, D-07743 Jena, Germany
| | - Petra Rösch
- Institut
für Physikalische Chemie and Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, D-07743 Jena, Germany
| | - Jürgen Popp
- Institut
für Physikalische Chemie and Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, D-07743 Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, D-07745 Jena, Germany
- Center
for Sepsis Control and Care (CSCC), Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
- InfectoGnostics Forschungscampus Jena e.V., Zentrum für
Angewandte Forschung, Philosophenweg 7, D-07743 Jena, Germany
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Mercante JW, Winchell JM. Current and emerging Legionella diagnostics for laboratory and outbreak investigations. Clin Microbiol Rev 2015; 28:95-133. [PMID: 25567224 PMCID: PMC4284297 DOI: 10.1128/cmr.00029-14] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.
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Affiliation(s)
- Jeffrey W Mercante
- Pneumonia Response and Surveillance Laboratory, Respiratory Diseases Branch, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jonas M Winchell
- Pneumonia Response and Surveillance Laboratory, Respiratory Diseases Branch, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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