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Denoncourt AM, Paquet VE, Charette SJ. Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria. Front Microbiol 2014; 5:240. [PMID: 24904553 PMCID: PMC4033053 DOI: 10.3389/fmicb.2014.00240] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 05/02/2014] [Indexed: 11/17/2022] Open
Abstract
Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging process. It is possible that packaging is more common than suspected and may play a major role in the persistence and transmission of pathogenic bacteria. To confirm the role of packaging in the propagation of infections, it is vital that the molecular mechanisms governing the packaging of bacteria by protozoa be identified as well as elements related to the ecology of this process in order to determine whether packaging acts as a Trojan Horse.
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Affiliation(s)
- Alix M Denoncourt
- Institut de Biologie Intégrative et des Systèmes, Université Laval Quebec City, QC, Canada ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec Quebec City, QC, Canada
| | - Valérie E Paquet
- Institut de Biologie Intégrative et des Systèmes, Université Laval Quebec City, QC, Canada ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec Quebec City, QC, Canada
| | - Steve J Charette
- Institut de Biologie Intégrative et des Systèmes, Université Laval Quebec City, QC, Canada ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec Quebec City, QC, Canada ; Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval Quebec City, QC, Canada
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Fokin SI, Schrallhammer M, Chiellini C, Verni F, Petroni G. Free-living ciliates as potential reservoirs for eukaryotic parasites: occurrence of a trypanosomatid in the macronucleus of Euplotes encysticus. Parasit Vectors 2014; 7:203. [PMID: 24774858 PMCID: PMC4022238 DOI: 10.1186/1756-3305-7-203] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 04/13/2014] [Indexed: 12/27/2022] Open
Abstract
Background Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts. Several genera infect insects and occur as monoxenous parasites especially in representatives of Diptera and Hemiptera. These trypanosomatid flagellates probably share the worldwide distribution of their hosts, which are often infested by large numbers of endoparasites. Traditionally, their taxonomy was based on morphology, host origin, and life cycle. Here we report the characterization of a trypanosomatid infection detected in a protozoan, a ciliate collected from a polluted freshwater pond in a suburb of New Delhi (India). Methods Live observations and morphological studies applying light, fluorescence and transmission electron microscopy were conducted. Molecular analyses of host and parasite were performed and used for phylogenetic reconstructions and species (host) or genus level (parasite) identification. Results Although the morphological characteristics were not revealing, a high similarity of the trypanosomatids 18S rRNA gene sequence to Herpetomonas ztiplika and Herpetomonas trimorpha (Kinetoplastida, Trypanosomatidae), both parasites of biting midges (Culicoides kibunensis and Culicoides truncorum, respectively) allowed the assignment to this genus. The majority of the host population displayed a heavy infection that significantly affected the shape of the host macronucleus, which was the main site of parasite localization. In addition, the growth rate of host cultures, identified as Euplotes encysticus according to cell morphology and 18S rRNA gene sequence, was severely impacted by the infection. Conclusions The host-parasite system described here represents a recent example of free-living protists acting as environmental reservoirs for parasitic eukaryotic microorganisms.
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Affiliation(s)
| | - Martina Schrallhammer
- Microbiology, Institute of Biology II, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany.
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53
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Croxatto A, Rieille N, Kernif T, Bitam I, Aeby S, Péter O, Greub G. Presence of Chlamydiales DNA in ticks and fleas suggests that ticks are carriers of Chlamydiae. Ticks Tick Borne Dis 2014; 5:359-65. [PMID: 24698831 DOI: 10.1016/j.ttbdis.2013.11.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/01/2013] [Accepted: 11/02/2013] [Indexed: 10/25/2022]
Abstract
The Chlamydiales order includes the Chlamydiaceae, Parachlamydiaceae, Waddliaceae, Simkaniaceae, Criblamydiaceae, Rhabdochlamydiaceae, Clavichlamydiaceae, and Piscichlamydiaceae families. Members of the Chlamydiales order are obligate intracellular bacteria that replicate within eukaryotic cells of different origins including humans, animals, and amoebae. Many of these bacteria are pathogens or emerging pathogens of both humans and animals, but their true diversity is largely underestimated, and their ecology remains to be investigated. Considering their potential threat on human health, it is important to expand our knowledge on the diversity of Chlamydiae, but also to define the host range colonized by these bacteria. Thus, using a new pan-Chlamydiales PCR, we analyzed the prevalence of Chlamydiales DNA in ticks and fleas, which are important vectors of several viral and bacterial infectious diseases. To conduct this study, 1340 Ixodes ricinus ticks prepared in 192 pools were collected in Switzerland and 55 other ticks belonging to different tick species and 97 fleas belonging to different flea species were harvested in Algeria. In Switzerland, the prevalence of Chlamydiales DNA in the 192 pools was equal to 28.1% (54/192) which represents an estimated prevalence in the 1340 individual ticks of between 4.0% and 28.4%. The pan-Chlamydiales qPCR was positive for 45% (25/55) of tick samples collected in Algeria. The sequencing of the positive qPCR amplicons revealed a high diversity of Chlamydiales species. Most of them belonged to the Rhabdochlamydiaceae and Parachlamydiaceae families. Thus, ticks may carry Chlamydiales and should thus be considered as possible vectors for Chlamydiales propagation to both humans and animals.
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Affiliation(s)
- Antony Croxatto
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
| | - Nadia Rieille
- Institut Central des Hôpitaux Valaisans, Infectious Diseases, Sion, Switzerland
| | | | | | - Sébastien Aeby
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
| | - Olivier Péter
- Institut Central des Hôpitaux Valaisans, Infectious Diseases, Sion, Switzerland
| | - Gilbert Greub
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland.
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54
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Lamoth F, Greub G. Fastidious intracellular bacteria as causal agents of community-acquired pneumonia. Expert Rev Anti Infect Ther 2014; 8:775-90. [DOI: 10.1586/eri.10.52] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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55
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de Barsy M, Greub G. Waddlia chondrophila: from biology to pathogenicity. Microbes Infect 2013; 15:1033-41. [DOI: 10.1016/j.micinf.2013.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/02/2013] [Accepted: 09/02/2013] [Indexed: 10/26/2022]
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Delafont V, Brouke A, Bouchon D, Moulin L, Héchard Y. Microbiome of free-living amoebae isolated from drinking water. WATER RESEARCH 2013; 47:6958-6965. [PMID: 24200009 DOI: 10.1016/j.watres.2013.07.047] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 07/11/2013] [Accepted: 07/22/2013] [Indexed: 06/02/2023]
Abstract
Free-living amoebae (FLA) are protozoa that can be found in water networks where they prey on bacteria within biofilms. Most bacteria are digested rapidly by phagocytosis, however some are able to survive within amoebae and some are even able to multiply, as it is the case for Legionella pneumophila. These resisting bacteria are a potential health problem as they could also resist to macrophage phagocytosis. Several publications already reported intra-amoebal bacteria but the methods of identification did not allow metagenomic analysis and are partly based on co-culture with one selected amoebal strain. The aim of our study was to conduct a rRNA-targeted metagenomic analysis on amoebae and intra-amoebal bacteria found in drinking water network, to provide the first FLA microbiome in environmental strains. Three sites of a water network were sampled during four months. Culturable FLA were isolated and total DNA was prepared, allowing purification of both amoebal and bacterial DNA. Metagenomic studies were then conducted through 18S or 16S amplicons sequencing. Hartmannella was by far the most represented genus of FLA. Regarding intra-amoebal bacteria, 54 genera were identified, among which 21 were newly described intra-amoebal bacteria, underlying the power of our approach. There were high differences in bacterial diversity between the three sites. Several genera were highly represented and/or found at least in two sites, underlying that these bacteria could be able to multiply within FLA. Our method is therefore useful to identify FLA microbiome and could be applied to other networks to have a more comprehensive view of intra-amoebal diversity.
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Affiliation(s)
- Vincent Delafont
- Université de Poitiers, UMR CNRS 7267, Ecologie et Biologie des Interactions (EBI), Poitiers, France; EAU DE PARIS, Direction de la Recherche & Développement et de la Qualité des eaux (DRDQE), Paris, France
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Pilhofer M, Aistleitner K, Ladinsky MS, König L, Horn M, Jensen GJ. Architecture and host interface of environmental chlamydiae revealed by electron cryotomography. Environ Microbiol 2013; 16:417-29. [PMID: 24118768 PMCID: PMC4949044 DOI: 10.1111/1462-2920.12299] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 09/26/2013] [Indexed: 01/14/2023]
Abstract
Chlamydiae comprise important pathogenic and symbiotic bacteria that alternate between morphologically and physiologically different life stages during their developmental cycle. Using electron cryotomography, we characterize the ultrastructure of the developmental stages of three environmental chlamydiae: Parachlamydia acanthamoebae, Protochlamydia amoebophila and Simkania negevensis. We show that chemical fixation and dehydration alter the cell shape of Parachlamydia and that the crescent body is not a developmental stage, but an artefact of conventional electron microscopy. We further reveal type III secretion systems of environmental chlamydiae at macromolecular resolution and find support for a chlamydial needle-tip protein. Imaging bacteria inside their host cells by cryotomography for the first time, we observe marked differences in inclusion morphology and development as well as host organelle recruitment between the three chlamydial organisms, with Simkania inclusions being tightly enveloped by the host endoplasmic reticulum. The study demonstrates the power of electron cryotomography to reveal structural details of bacteria-host interactions that are not accessible using traditional methods.
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Affiliation(s)
- Martin Pilhofer
- Division of Biology, California Institute of Technology, Pasadena, CA, 91125, USA; Howard Hughes Medical Institute, Pasadena, CA, 91125, USA
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58
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Jacquier N, Aeby S, Lienard J, Greub G. Discovery of new intracellular pathogens by amoebal coculture and amoebal enrichment approaches. J Vis Exp 2013:e51055. [PMID: 24192667 DOI: 10.3791/51055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at all on selective media that are usually used to cultivate bacteria. For this reason, many of these pathogens were discovered only recently or following important outbreaks. These pathogens are often associated with amoebae, which serve as host-cell and allow the survival and growth of the bacteria. We intend here to provide a demonstration of two techniques that allow isolation and characterization of intracellular pathogens present in clinical or environmental samples: the amoebal coculture and the amoebal enrichment. Amoebal coculture allows recovery of intracellular bacteria by inoculating the investigated sample onto an amoebal lawn that can be infected and lysed by the intracellular bacteria present in the sample. Amoebal enrichment allows recovery of amoebae present in a clinical or environmental sample. This can lead to discovery of new amoebal species but also of new intracellular bacteria growing specifically in these amoebae. Together, these two techniques help to discover new intracellular bacteria able to grow in amoebae. Because of their ability to infect amoebae and resist phagocytosis, these intracellular bacteria might also escape phagocytosis by macrophages and thus, be pathogenic for higher eukaryotes.
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Affiliation(s)
- Nicolas Jacquier
- Institute of Microbiology, University Hospital Center and University of Lausanne
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59
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Croxatto A, Murset V, Chassot B, Greub G. Early expression of the type III secretion system of Parachlamydia acanthamoebae during a replicative cycle within its natural host cell Acanthamoeba castellanii. Pathog Dis 2013; 69:159-75. [PMID: 23861207 DOI: 10.1111/2049-632x.12065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/28/2013] [Accepted: 07/01/2013] [Indexed: 12/26/2022] Open
Abstract
The type three secretion system (T3SS) operons of Chlamydiales bacteria are distributed in different clusters along their chromosomes and are conserved at both the level of sequence and genetic organization. A complete characterization of the temporal expression of multiple T3SS components at the transcriptional and protein levels has been performed in Parachlamydia acanthamoebae, replicating in its natural host cell Acanthamoeba castellanii. The T3SS components were classified in four different temporal clusters depending on their pattern of expression during the early, mid- and late phases of the infectious cycle. The putative T3SS transcription units predicted in Parachlamydia are similar to those described in Chlamydia trachomatis, suggesting that T3SS units of transcriptional expression are highly conserved among Chlamydiales bacteria. The maximal expression and activation of the T3SS of Parachlamydia occurred during the early to mid-phase of the infectious cycle corresponding to a critical phase during which the intracellular bacterium has (1) to evade and/or block the lytic pathway of the amoeba, (2) to differentiate from elementary bodies (EBs) to reticulate bodies (RBs), and (3) to modulate the maturation of its vacuole to create a replicative niche able to sustain efficient bacterial growth.
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Affiliation(s)
- Antony Croxatto
- Center for Research on Intracellular Bacteria (CRIB), Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
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60
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de Barsy M, Greub G. Functional genomics of intracellular bacteria. Brief Funct Genomics 2013; 12:341-53. [DOI: 10.1093/bfgp/elt012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
Afipia birgiae is an alphaproteobacterium from the family Bradyrhizobiaceae, growing in amoebae, and a potential human pathogen. We sequenced the genome of type strain 34632(T). It is composed of 5,325,467 bp and contains 5,160 protein-coding genes and 53 RNA genes, including 3 rRNA genes.
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Matsuo J, Nakamura S, Ito A, Yamazaki T, Ishida K, Hayashi Y, Yoshida M, Takahashi K, Sekizuka T, Takeuchi F, Kuroda M, Nagai H, Hayashida K, Sugimoto C, Yamaguchi H. Protochlamydia induces apoptosis of human HEp-2 cells through mitochondrial dysfunction mediated by chlamydial protease-like activity factor. PLoS One 2013; 8:e56005. [PMID: 23409113 PMCID: PMC3569409 DOI: 10.1371/journal.pone.0056005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/04/2013] [Indexed: 11/22/2022] Open
Abstract
Obligate amoebal endosymbiotic bacterium Protochlamydia with ancestral pathogenic chlamydial features evolved to survive within protist hosts, such as Acanthamoba, 0.7–1.4 billion years ago, but not within vertebrates including humans. This observation raises the possibility that interactions between Protochlamydia and human cells may result in a novel cytopathic effect, leading to new insights into host-parasite relationships. Previously, we reported that Protochlamydia induces apoptosis of the immortalized human cell line, HEp-2. In this study, we attempted to elucidate the molecular mechanism underlying this apoptosis. We first confirmed that, upon stimulation with the bacteria, poly (ADP-ribose) polymerase (PARP) was cleaved at an early stage in HEp-2 cells, which was dependent on the amount of bacteria. A pan-caspase inhibitor and both caspase-3 and -9 inhibitors similarly inhibited the apoptosis of HEp-2 cells. A decrease of the mitochondrial membrane potential was also confirmed. Furthermore, lactacystin, an inhibitor of chlamydial protease-like activity factor (CPAF), blocked the apoptosis. Cytochalasin D also inhibited the apoptosis, which was dependent on the drug concentration, indicating that bacterial entry into cells was required to induce apoptosis. Interestingly, Yersinia type III inhibitors (ME0052, ME0053, and ME0054) did not have any effect on the apoptosis. We also confirmed that the Protochlamydia used in this study possessed a homologue of the cpaf gene and that two critical residues, histidine-101 and serine-499 of C. trachomatis CPAF in the active center, were conserved. Thus, our results indicate that after entry, Protochlamydia-secreted CPAF induces mitochondrial dysfunction with a decrease of the membrane potential, followed by caspase-9, caspase-3 and PARP cleavages for apoptosis. More interestingly, because C. trachomatis infection can block the apoptosis, our finding implies unique features of CPAF between pathogenic and primitive chlamydiae.
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Affiliation(s)
- Junji Matsuo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Atsushi Ito
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tomohiro Yamazaki
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kasumi Ishida
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yasuhiro Hayashi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Mitsutaka Yoshida
- Division of Ultrastructural Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Kaori Takahashi
- Division of Ultrastructural Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tsuyoshi Sekizuka
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Fumihiko Takeuchi
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Makoto Kuroda
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Hiroki Nagai
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Kyoko Hayashida
- Research Center for Zoonosis Control, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Chihiro Sugimoto
- Research Center for Zoonosis Control, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
- * E-mail:
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63
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Clark LC, Seipke RF, Prieto P, Willemse J, van Wezel GP, Hutchings MI, Hoskisson PA. Mammalian cell entry genes in Streptomyces may provide clues to the evolution of bacterial virulence. Sci Rep 2013; 3:1109. [PMID: 23346366 PMCID: PMC3552289 DOI: 10.1038/srep01109] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 12/06/2012] [Indexed: 11/09/2022] Open
Abstract
Understanding the evolution of virulence is key to appreciating the role specific loci play in pathogenicity. Streptomyces species are generally non-pathogenic soil saprophytes, yet within their genome we can find homologues of virulence loci. One example of this is the mammalian cell entry (mce) locus, which has been characterised in Mycobacterium tuberculosis. To investigate the role in Streptomyces we deleted the mce locus and studied its impact on cell survival, morphology and interaction with other soil organisms. Disruption of the mce cluster resulted in virulence towards amoebae (Acanthamoeba polyphaga) and reduced colonization of plant (Arabidopsis) models, indicating these genes may play an important role in Streptomyces survival in the environment. Our data suggest that loss of mce in Streptomyces spp. may have profound effects on survival in a competitive soil environment, and provides insight in to the evolution and selection of these genes as virulence factors in related pathogenic organisms.
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Affiliation(s)
- Laura C Clark
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow, UK
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64
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Parola P, Renvoisé A, Botelho-Nevers E, La Scola B, Desnues C, Raoult D. Acanthamoeba polyphaga mimivirus virophage seroconversion in travelers returning from Laos. Emerg Infect Dis 2013; 18:1500-2. [PMID: 22932431 PMCID: PMC3437713 DOI: 10.3201/eid1809.120099] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
During January 2010, a husband and wife returned from Laos to France with probable parasitic disease. Increased antibodies against an Acanthamoeba polyphaga mimivirus virophage indicated seroconversion. While in Laos, they had eaten raw fish, a potential source of the virophage. This virophage, associated with giant viruses suspected to cause pneumonia, could be an emerging pathogen.
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65
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Bertelli C, Greub G. Lateral gene exchanges shape the genomes of amoeba-resisting microorganisms. Front Cell Infect Microbiol 2012; 2:110. [PMID: 22919697 PMCID: PMC3423634 DOI: 10.3389/fcimb.2012.00110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 08/01/2012] [Indexed: 12/05/2022] Open
Abstract
Based on Darwin's concept of the tree of life, vertical inheritance was thought to be dominant, and mutations, deletions, and duplication were streaming the genomes of living organisms. In the current genomic era, increasing data indicated that both vertical and lateral gene inheritance interact in space and time to trigger genome evolution, particularly among microorganisms sharing a given ecological niche. As a paradigm to their diversity and their survival in a variety of cell types, intracellular microorganisms, and notably intracellular bacteria, were considered as less prone to lateral genetic exchanges. Such specialized microorganisms generally have a smaller gene repertoire because they do rely on their host's factors for some basic regulatory and metabolic functions. Here we review events of lateral gene transfer (LGT) that illustrate the genetic exchanges among intra-amoebal microorganisms or between the microorganism and its amoebal host. We tentatively investigate the functions of laterally transferred genes in the light of the interaction with their host as they should confer a selective advantage and success to the amoeba-resisting microorganisms (ARMs).
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Affiliation(s)
- Claire Bertelli
- Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne Lausanne, Switzerland
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66
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Hospodsky D, Qian J, Nazaroff WW, Yamamoto N, Bibby K, Rismani-Yazdi H, Peccia J. Human occupancy as a source of indoor airborne bacteria. PLoS One 2012; 7:e34867. [PMID: 22529946 PMCID: PMC3329548 DOI: 10.1371/journal.pone.0034867] [Citation(s) in RCA: 271] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 03/06/2012] [Indexed: 02/01/2023] Open
Abstract
Exposure to specific airborne bacteria indoors is linked to infectious and noninfectious adverse health outcomes. However, the sources and origins of bacteria suspended in indoor air are not well understood. This study presents evidence for elevated concentrations of indoor airborne bacteria due to human occupancy, and investigates the sources of these bacteria. Samples were collected in a university classroom while occupied and when vacant. The total particle mass concentration, bacterial genome concentration, and bacterial phylogenetic populations were characterized in indoor, outdoor, and ventilation duct supply air, as well as in the dust of ventilation system filters and in floor dust. Occupancy increased the total aerosol mass and bacterial genome concentration in indoor air PM(10) and PM(2.5) size fractions, with an increase of nearly two orders of magnitude in airborne bacterial genome concentration in PM(10). On a per mass basis, floor dust was enriched in bacterial genomes compared to airborne particles. Quantitative comparisons between bacterial populations in indoor air and potential sources suggest that resuspended floor dust is an important contributor to bacterial aerosol populations during occupancy. Experiments that controlled for resuspension from the floor implies that direct human shedding may also significantly impact the concentration of indoor airborne particles. The high content of bacteria specific to the skin, nostrils, and hair of humans found in indoor air and in floor dust indicates that floors are an important reservoir of human-associated bacteria, and that the direct particle shedding of desquamated skin cells and their subsequent resuspension strongly influenced the airborne bacteria population structure in this human-occupied environment. Inhalation exposure to microbes shed by other current or previous human occupants may occur in communal indoor environments.
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Affiliation(s)
- Denina Hospodsky
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
| | - Jing Qian
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
| | - William W. Nazaroff
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, United States of America
| | - Naomichi Yamamoto
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
- Japan Society of the Promotion of Science, Ichiban-cho 8, Chiyoda-ku, Tokyo, Japan
| | - Kyle Bibby
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
| | - Hamid Rismani-Yazdi
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
| | - Jordan Peccia
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States of America
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Coulon C, Eterpi M, Greub G, Collignon A, McDonnell G, Thomas V. Amoebal host range, host-free survival and disinfection susceptibility of environmental Chlamydiae as compared to Chlamydia trachomatis. ACTA ACUST UNITED AC 2012; 64:364-73. [PMID: 22141597 DOI: 10.1111/j.1574-695x.2011.00919.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 11/30/2011] [Accepted: 11/30/2011] [Indexed: 11/28/2022]
Abstract
The term 'Chlamydia-like organisms' encompasses obligate intracellular bacterial species phylogenetically close to Chlamydiaceae. Most are associated with free-living amoebae, and several could be responsible for respiratory tract infections and abortion in human and animals. Despite increasing concern about their pathogenic role, the prevalence, biodiversity and ecology of Chlamydia-related bacteria still remain largely unknown. In this study, six members of the Chlamydiales were tested, including Parachlamydia acanthamoebae (two different strains), Protochlamydia naegleriophila, Waddlia chondrophila, Criblamydia sequanensis and Chlamydia trachomatis as a reference. Intracellular growth was tested in 11 different Acanthamoeba strains, demonstrating significant differences in host susceptibilities to infection depending on strains investigated. Survival of host-free bacteria in suspension or dried onto surfaces was also explored, demonstrating that Chlamydia-like organisms present better survival capacity than C. trachomatis. Longer survival times were observed for bacteria suspended in rich culture medium, with survivors being detected after 10 weeks incubation. We also tested susceptibility of host-free Chlamydia-like organisms to several disinfection treatments. Each chemical biocide tested reduced viability of host-free Chlamydia by more than 4 logs. Conversely, all Chlamydia-like organisms tested resisted exposure at 55 °C for 10 min, while C. trachomatis was completely inactivated.
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68
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Taylor M, Mediannikov O, Raoult D, Greub G. Endosymbiotic bacteria associated with nematodes, ticks and amoebae. ACTA ACUST UNITED AC 2011; 64:21-31. [PMID: 22126456 DOI: 10.1111/j.1574-695x.2011.00916.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 11/21/2011] [Accepted: 11/21/2011] [Indexed: 01/20/2023]
Abstract
Endosymbiosis is a mutualistic, parasitic or commensal symbiosis in which one symbiont is living within the body of another organism. Such symbiotic relationship with free-living amoebae and arthropods has been reported with a large biodiversity of microorganisms, encompassing various bacterial clades and to a lesser extent some fungi and viruses. By contrast, current knowledge on symbionts of nematodes is still mainly restricted to Wolbachia and its interaction with filarial worms that lead to increased pathogenicity of the infected nematode. In this review article, we aim to highlight the main characteristics of symbionts in term of their ecology, host cell interactions, parasitism and co-evolution, in order to stimulate future research in a field that remains largely unexplored despite the availability of modern tools.
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Affiliation(s)
- Mark Taylor
- Molecular and Biochemical Parasitology Group, Liverpool School of Tropical Medicine, Liverpool, UK
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69
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Niemi S, Greub G, Puolakkainen M. Chlamydia-related bacteria in respiratory samples in Finland. Microbes Infect 2011; 13:824-7. [DOI: 10.1016/j.micinf.2011.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/15/2011] [Accepted: 04/15/2011] [Indexed: 10/18/2022]
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70
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Bozzaro S, Eichinger L. The professional phagocyte Dictyostelium discoideum as a model host for bacterial pathogens. Curr Drug Targets 2011; 12:942-54. [PMID: 21366522 PMCID: PMC3267156 DOI: 10.2174/138945011795677782] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 10/26/2010] [Indexed: 01/24/2023]
Abstract
The use of simple hosts such as Dictyostelium discoideum in the study of host pathogen interactions offers a number of advantages and has steadily increased in recent years. Infection-specific genes can often only be studied in a very limited way in man and even in the mouse model their analysis is usually expensive, time consuming and technically challenging or sometimes even impossible. In contrast, their functional analysis in D. discoideum and other simple model organisms is often easier, faster and cheaper. Because host-pathogen interactions necessarily involve two organisms, it is desirable to be able to genetically manipulate both the pathogen and its host. Particularly suited are those hosts, like D. discoideum, whose genome sequence is known and annotated and for which excellent genetic and cell biological tools are available in order to dissect the complex crosstalk between host and pathogen. The review focusses on host-pathogen interactions of D. discoideum with Legionella pneumophila, mycobacteria, and Salmonella typhimurium which replicate intracellularly.
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Affiliation(s)
- Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University of Turin, Ospedale S. Luigi, 10043 Orbassano, Italy.
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71
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Lamoth F, Jaton K, Vaudaux B, Greub G. Parachlamydia and Rhabdochlamydia: Emerging Agents of Community-Acquired Respiratory Infections in Children. Clin Infect Dis 2011; 53:500-1. [DOI: 10.1093/cid/cir420] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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72
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Thomas V, Bertelli C, Collyn F, Casson N, Telenti A, Goesmann A, Croxatto A, Greub G. Lausannevirus, a giant amoebal virus encoding histone doublets. Environ Microbiol 2011; 13:1454-66. [DOI: 10.1111/j.1462-2920.2011.02446.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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73
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Thomas JM, Ashbolt NJ. Do free-living amoebae in treated drinking water systems present an emerging health risk? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:860-9. [PMID: 21194220 DOI: 10.1021/es102876y] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
There is an expanding body of evidence that free-living amoebae (FLA) increase both the numbers and virulence of water-based, human-pathogenic, amoeba-resisting microorganisms (ARM). Legionella spp., Mycobacterium spp., and other opportunistic human pathogens are known to be both ARM and also the etiologic agents of potentially fatal human lung infections. However, comparatively little is known about the FLA that may facilitate ARM growth in drinking water. This review examines the available literature on FLA in treated drinking water systems; in total 26 studies from 18 different countries. FLA were reported to breakthrough the water treatment barrier and enter distribution systems, in addition to the expected post-treatment system ingress. Once in the distribution system there is evidence of FLA colonization and regrowth especially in reservoirs and in-premise plumbing storage tanks. At the point of use the average FLA detection rate was 45% but highly variable (n = 16, σ = 31) due to both differences in both assay methods and the type of water systems examined. This review reveals that FLA are consistently detected in treated drinking water systems around the world and present a yet unquantified emerging health risk. However, more research is urgently required before accurate risks assessments can be undertaken to assess the impacts on human health, in households and institutions, due to exposure to FLA facilitated pathogenic ARM.
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Affiliation(s)
- Jacqueline M Thomas
- Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, NSW 2052 Australia.
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Roger T, Casson N, Croxatto A, Entenza JM, Pusztaszeri M, Akira S, Reymond MK, Le Roy D, Calandra T, Greub G. Role of MyD88 and Toll-like receptors 2 and 4 in the sensing of Parachlamydia acanthamoebae. Infect Immun 2010; 78:5195-201. [PMID: 20837714 PMCID: PMC2981336 DOI: 10.1128/iai.00786-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/27/2010] [Accepted: 09/02/2010] [Indexed: 02/02/2023] Open
Abstract
Parachlamydia acanthamoebae is a Chlamydia-related organism whose pathogenic role in pneumonia is supported by serological and molecular clinical studies and an experimental mouse model of lung infection. Toll-like receptors (TLRs) play a seminal role in sensing microbial products and initiating innate immune responses. The aim of this study was to investigate the roles of MyD88, TLR2, and TLR4 in the interaction of Parachlamydia with macrophages. Here, we showed that Parachlamydia entered bone-marrow derived macrophages (BMDMs) in a TLR-independent manner but did not multiply intracellularly. Interestingly, compared to live bacteria, heat-inactivated Parachlamydia induced the production of substantial amounts of tumor necrosis factor alpha (TNF), interleukin-6 (IL-6), and IL-12p40 by BMDMs and of TNF and IL-6 by peritoneal macrophages as well as RAW 264.7 and J774 macrophage cell lines. Cytokine production by BMDMs, which was partially inhibited upon trypsin treatment of Parachlamydia, was dependent on MyD88, TLR4, and, to a lesser extent, TLR2. Finally, MyD88(-/-), TLR4(-/-), and TLR2(-/-) mice were as resistant as wild-type mice to lung infection following the intratracheal instillation of Parachlamydia. Thus, in contrast to Chlamydia pneumoniae, Parachlamydia acanthamoebae weakly stimulates macrophages, potentially compensating for its low replication capacity in macrophages by escaping the innate immune surveillance.
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Affiliation(s)
- Thierry Roger
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Nicola Casson
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Antony Croxatto
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - José Manuel Entenza
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Marc Pusztaszeri
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shizuo Akira
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Marlies Knaup Reymond
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Didier Le Roy
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Thierry Calandra
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Gilbert Greub
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Center for Research on Intracellular Bacteria, Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland, Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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Abstract
Intracellular bacteria live in an environment rich in most essential metabolites but need special mechanisms to access these substrates. Nucleotide transport proteins (NTTs) catalyze the import of ATP and other nucleotides from the eukaryotic host into the bacterial cell and render de novo synthesis of these compounds dispensable. The draft genome sequence of Simkania negevensis strain Z, a chlamydial organism considered a newly emerging pathogen, revealed four genes encoding putative nucleotide transport proteins (SnNTT1 to SnNTT4), all of which are transcribed during growth of S. negevensis in Acanthamoeba host cells, as confirmed by reverse transcription-PCR. Using heterologous expression in Escherichia coli, we could show that SnNTT1 functions as an ATP/ADP antiporter, SnNTT2 as a guanine nucleotide/ATP/H(+) symporter driven by the membrane potential, and SnNTT3 as a nucleotide triphosphate antiporter. In addition, SnNTT3 is able to transport dCTP, which has not been shown for a prokaryotic transport protein before. No substrate could be identified for SnNTT4. Taking these data together, S. negevensis employs a set of nucleotide transport proteins to efficiently tap its host's energy and nucleotide pools. Although similar to other chlamydiae, these transporters show distinct and unique adaptations with respect to substrate specificities and mode of transport.
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Legionella pneumophila strain 130b possesses a unique combination of type IV secretion systems and novel Dot/Icm secretion system effector proteins. J Bacteriol 2010; 192:6001-16. [PMID: 20833813 DOI: 10.1128/jb.00778-10] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Legionella pneumophila is a ubiquitous inhabitant of environmental water reservoirs. The bacteria infect a wide variety of protozoa and, after accidental inhalation, human alveolar macrophages, which can lead to severe pneumonia. The capability to thrive in phagocytic hosts is dependent on the Dot/Icm type IV secretion system (T4SS), which translocates multiple effector proteins into the host cell. In this study, we determined the draft genome sequence of L. pneumophila strain 130b (Wadsworth). We found that the 130b genome encodes a unique set of T4SSs, namely, the Dot/Icm T4SS, a Trb-1-like T4SS, and two Lvh T4SS gene clusters. Sequence analysis substantiated that a core set of 107 Dot/Icm T4SS effectors was conserved among the sequenced L. pneumophila strains Philadelphia-1, Lens, Paris, Corby, Alcoy, and 130b. We also identified new effector candidates and validated the translocation of 10 novel Dot/Icm T4SS effectors that are not present in L. pneumophila strain Philadelphia-1. We examined the prevalence of the new effector genes among 87 environmental and clinical L. pneumophila isolates. Five of the new effectors were identified in 34 to 62% of the isolates, while less than 15% of the strains tested positive for the other five genes. Collectively, our data show that the core set of conserved Dot/Icm T4SS effector proteins is supplemented by a variable repertoire of accessory effectors that may partly account for differences in the virulences and prevalences of particular L. pneumophila strains.
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Megacities as sources for pathogenic bacteria in rivers and their fate downstream. Int J Microbiol 2010; 2011. [PMID: 20885968 PMCID: PMC2946570 DOI: 10.1155/2011/798292] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/09/2010] [Accepted: 07/19/2010] [Indexed: 12/27/2022] Open
Abstract
Poor sanitation, poor treatments of waste water, as well as catastrophic floods introduce pathogenic bacteria into rivers, infecting and killing many people. The goal of clean water for everyone has to be achieved with a still growing human population and their rapid concentration in large cities, often megacities. How long introduced pathogens survive in rivers and what their niches are remain poorly known but essential to control water-borne diseases in megacities. Biofilms are often niches for various pathogens because they possess high resistances against environmental stress. They also facilitate gene transfers of antibiotic resistance genes which become an increasing health problem. Beside biofilms, amoebae are carriers of pathogenic bacteria and niches for their survival. An overview about our current understanding of the fate and niches of pathogens in rivers, the multitude of microbial community interactions, and the impact of severe flooding, a prerequisite to control pathogens in polluted rivers, is given.
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78
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Loret JF, Greub G. Free-living amoebae: Biological by-passes in water treatment. Int J Hyg Environ Health 2010; 213:167-75. [PMID: 20418158 DOI: 10.1016/j.ijheh.2010.03.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 03/24/2010] [Accepted: 03/24/2010] [Indexed: 11/30/2022]
Abstract
Free-living amoebae constitute reservoirs for many bacteria including not only well-known pathogens but also emerging pathogens responsible for respiratory diseases, and contribute to the protection, survival and dissemination of these bacteria in water systems, despite the application of disinfection or thermal treatments. In this article we review the available information on the presence of free-living amoebae and amoebae-resisting bacteria in drinking water systems, on the factors that contribute to their presence in the water and/or the biofilms, on the possible control measures and their effectiveness, and we identify some gaps in current knowledge needing further research.
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Affiliation(s)
- Jean-François Loret
- Suez Environnement, CIRSEE, 38 rue du Président Wilson, 78230 Le Pecq, France.
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79
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Corsaro D, Pages GS, Catalan V, Loret JF, Greub G. Biodiversity of amoebae and amoeba-associated bacteria in water treatment plants. Int J Hyg Environ Health 2010; 213:158-66. [PMID: 20403728 DOI: 10.1016/j.ijheh.2010.03.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 02/18/2010] [Accepted: 03/19/2010] [Indexed: 11/27/2022]
Abstract
In this study, we enlarged our previous investigation focusing on the biodiversity of chlamydiae and amoebae in a drinking water treatment plant, by the inclusion of two additional plants and by searching also for the presence of legionellae and mycobacteria. Autochthonous amoebae were recovered onto non-nutritive agar, identified by 18S rRNA gene sequencing, and screened for the presence of bacterial endosymbionts. Bacteria were also searched for by Acanthamoeba co-culture. From a total of 125 samples, we recovered 38 amoebae, among which six harboured endosymbionts (three chlamydiae and three legionellae). In addition, we recovered by amoebal co-culture 11 chlamydiae, 36 legionellae (no L. pneumophila), and 24 mycobacteria (all rapid-growers). Two plants presented a similar percentage of samples positive for chlamydiae (11%), mycobacteria (20%) and amoebae (27%), whereas in the third plant the number of recovered bacteria was almost twice higher. Each plant exhibited a relatively high specific microbiota. Amoebae were mainly represented by various Naegleria species, Acanthamoeba species and Hartmannella vermiformis. Parachlamydiaceae were the most abundant chlamydiae (8 strains in total), and in this study we recovered a new genus-level strain, along with new chlamydiae previously reported. Similarly, about 66% of the recovered legionellae and 47% of the isolated mycobacteria could represent new species. Our work highlighted a high species diversity among legionellae and mycobacteria, dominated by putative new species, and it confirmed the presence of chlamydiae in these artificial water systems.
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Affiliation(s)
- Daniele Corsaro
- Center for Research on Intracellular Bacteria, Institute of Microbiology, Faculty of Biology and Medecine, University of Lausanne, Bugnon 46, 1011 Lausanne, Switzerland
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