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Collingro A, Köstlbacher S, Siegl A, Toenshoff ER, Schulz F, Mitchell SO, Weinmaier T, Rattei T, Colquhoun DJ, Horn M. The Fish Pathogen "Candidatus Clavichlamydia salmonicola"-A Missing Link in the Evolution of Chlamydial Pathogens of Humans. Genome Biol Evol 2023; 15:evad147. [PMID: 37615694 PMCID: PMC10448858 DOI: 10.1093/gbe/evad147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2023] [Indexed: 08/25/2023] Open
Abstract
Chlamydiae like Chlamydia trachomatis and Chlamydia psittaci are well-known human and animal pathogens. Yet, the chlamydiae are a much larger group of evolutionary ancient obligate intracellular bacteria that includes predominantly symbionts of protists and diverse animals. This makes them ideal model organisms to study evolutionary transitions from symbionts in microbial eukaryotes to pathogens of humans. To this end, comparative genome analysis has served as an important tool. Genome sequence data for many chlamydial lineages are, however, still lacking, hampering our understanding of their evolutionary history. Here, we determined the first high-quality draft genome sequence of the fish pathogen "Candidatus Clavichlamydia salmonicola", representing a separate genus within the human and animal pathogenic Chlamydiaceae. The "Ca. Clavichlamydia salmonicola" genome harbors genes that so far have been exclusively found in Chlamydia species suggesting that basic mechanisms important for the interaction with chordate hosts have evolved stepwise in the history of chlamydiae. Thus, the genome sequence of "Ca. Clavichlamydia salmonicola" allows to constrain candidate genes to further understand the evolution of chlamydial virulence mechanisms required to infect mammals.
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Affiliation(s)
- Astrid Collingro
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Stephan Köstlbacher
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Alexander Siegl
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Elena R Toenshoff
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich (ETH), Zürich, Switzerland
| | - Frederik Schulz
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- DOE Joint Genome Institute, Berkeley, California, USA
| | | | - Thomas Weinmaier
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Thomas Rattei
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | | | - Matthias Horn
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
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2
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Quezada‐Rodriguez PR, Taylor RS, Downes J, Egan F, White S, Brenan A, Rigby M, Nowak BF, Ruane NM, Wynne JW. Prevalence of epitheliocystis in freshwater Atlantic salmon reared in flow-through and recirculation aquaculture systems. JOURNAL OF FISH DISEASES 2022; 45:1721-1731. [PMID: 36017570 PMCID: PMC9805179 DOI: 10.1111/jfd.13694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/11/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
Epitheliocystis, an intracellular bacterial infection in the gills and skin epithelium, has been frequently reported in Atlantic salmon (Salmo salar) during freshwater production in a number of countries. This study describes the prevalence and intensity of a natural epitheliocystis infection present in the gills of two strains of Atlantic salmon reared in either a flow-through (FT) or a recirculation aquaculture system (RAS) in Ireland. Repeated sampling of gills prior to and throughout seawater transfer, histology and quantitative real-time PCR were used to determine infection prevalence and intensity. Despite no clinical gill disease, and minor histopathological changes, epitheliocystis lesions were identified in histology at all time points. Specific PCR confirmed the presence of Candidatus Clavichlamydia salmonicola in both strains and its number of copies was correlated with intensity of epitheliocystis lesions. A significant interaction between hatchery system and fish strain on the prevalence and intensity of gill epitheliocystis was found both using histological and molecular methods. Specifically, fish from FT had higher prevalence and intensity than RAS reared fish and within FT, the Irish cohort were more affected than Icelandic.
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Affiliation(s)
- Petra R. Quezada‐Rodriguez
- Livestock and AquacultureCommonwealth Scientific and Industrial Research Organisation, Agriculture and FoodHobartTasmaniaAustralia
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaLauncestonTasmaniaAustralia
| | - Richard S. Taylor
- Livestock and AquacultureCommonwealth Scientific and Industrial Research Organisation, Agriculture and FoodHobartTasmaniaAustralia
| | | | | | | | | | - Megan Rigby
- Livestock and AquacultureCommonwealth Scientific and Industrial Research Organisation, Agriculture and FoodHobartTasmaniaAustralia
| | - Barbara F. Nowak
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaLauncestonTasmaniaAustralia
| | | | - James W. Wynne
- Livestock and AquacultureCommonwealth Scientific and Industrial Research Organisation, Agriculture and FoodHobartTasmaniaAustralia
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3
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Liu F, Feng Y, Geng Y, Chen D, Ou Yang P, Huang X, Guo H, Zuo Z, Deng H, Fang J. Epitheliocystis caused by a novel Chlamydia emerging in Spinibarbus denticulatus in China. DISEASES OF AQUATIC ORGANISMS 2022; 150:31-36. [PMID: 35796509 DOI: 10.3354/dao03672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Epitheliocystis is an emerging and global aquaculture disease caused by a diverse range of bacteria of the order Chlamydiales. Here we report a case of epitheliocystis caused by a novel Chlamydia bacterium, which resulted in 40% mortality in cultured cyprinids (Spinibarbus denticulatus). The affected fish exhibited lethargy, were observed swimming near the oxygen pump and subsequently died. Histopathology analysis revealed that lesions were concentrated mainly on the gills. The epithelial cells of the damaged gill lamellae showed hyperplasia, fusion and adhesion, and were characterized by inflammation and necrosis. Inclusion bodies were observed in some proliferating epithelial cells at the tips of the gill lamellae and were accompanied by different degrees of mucous cell proliferation. Transmission electron microscopy examination clearly showed the morphological characteristics of chlamydia-like bacteria in epithelial cells. In addition, 16S rRNA sequencing (752 bp) and molecular phylogenetic analyses revealed that epitheliocystis agents detected in S. denticulatus belonged to a novel family, Chlamydiaceae. This is the first report of epitheliocystis in cultured fish in China, and the findings in this study increase the range of hosts affected by epitheliocystis.
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Affiliation(s)
- Fan Liu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
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4
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Novacovsky GN, Palacios MG, Sueiro MC. Epitheliocystis in wild marine fishes and its relation with anthropogenic pollution. JOURNAL OF FISH BIOLOGY 2021; 99:1519-1523. [PMID: 34159586 DOI: 10.1111/jfb.14826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 05/28/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
Epitheliocystis is a fish disease with recorded in increasing numbers globally. Here we show that (a) pollution-exposed wild marine fishes have higher infection prevalence than nonexposed individuals from reference sites, suggesting that anthropogenic pollution predisposes individuals to this disease in natural systems, (b) the effect of pollution on infection status did not vary significantly between two sympatric fish species, and (c) infected and noninfected individuals from both species did not differ significantly in selected immune and general-health parameters, a result that deserves further study with increased sample sizes.
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Affiliation(s)
- Gabriela N Novacovsky
- Centro para el Estudio de Sistemas Marinos, Centro Nacional Patagónico - Consejo Nacional de Investigaciones Científicas y Técnicas), Puerto Madryn, Argentina
| | - María G Palacios
- Centro para el Estudio de Sistemas Marinos, Centro Nacional Patagónico - Consejo Nacional de Investigaciones Científicas y Técnicas), Puerto Madryn, Argentina
| | - María C Sueiro
- Centro para el Estudio de Sistemas Marinos, Centro Nacional Patagónico - Consejo Nacional de Investigaciones Científicas y Técnicas), Puerto Madryn, Argentina
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5
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Taylor-Brown A, Pillonel T, Greub G, Vaughan L, Nowak B, Polkinghorne A. Metagenomic Analysis of Fish-Associated Ca. Parilichlamydiaceae Reveals Striking Metabolic Similarities to the Terrestrial Chlamydiaceae. Genome Biol Evol 2018; 10:2587-2595. [PMID: 30202970 PMCID: PMC6171736 DOI: 10.1093/gbe/evy195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2018] [Indexed: 12/13/2022] Open
Abstract
Chlamydiae are an example of obligate intracellular bacteria that possess highly reduced, compact genomes (1.0-3.5 Mbp), reflective of their abilities to sequester many essential nutrients from the host that they no longer need to synthesize themselves. The Chlamydiae is a phylum with a very wide host range spanning mammals, birds, fish, invertebrates, and unicellular protists. This ecological and phylogenetic diversity offers ongoing opportunities to study intracellular survival and metabolic pathways and adaptations. Of particular evolutionary significance are Chlamydiae from the recently proposed Ca. Parilichlamydiaceae, the earliest diverging clade in this phylum, species of which are found only in aquatic vertebrates. Gill extracts from three Chlamydiales-positive Australian aquaculture species (Yellowtail kingfish, Striped trumpeter, and Barramundi) were subject to DNA preparation to deplete host DNA and enrich microbial DNA, prior to metagenome sequencing. We assembled chlamydial genomes corresponding to three Ca. Parilichlamydiaceae species from gill metagenomes, and conducted functional genomics comparisons with diverse members of the phylum. This revealed highly reduced genomes more similar in size to the terrestrial Chlamydiaceae, standing in contrast to members of the Chlamydiae with a demonstrated cosmopolitan host range. We describe a reduction in genes encoding synthesis of nucleotides and amino acids, among other nutrients, and an enrichment of predicted transport proteins. Ca. Parilichlamydiaceae share 342 orthologs with other chlamydial families. We hypothesize that the genome reduction exhibited by Ca. Parilichlamydiaceae and Chlamydiaceae is an example of within-phylum convergent evolution. The factors driving these events remain to be elucidated.
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Affiliation(s)
- Alyce Taylor-Brown
- USC Animal Research Centre, Faculty of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
| | - Trestan Pillonel
- Institute of Microbiology, University of Lausanne and University Hospital Center, Switzerland
| | - Gilbert Greub
- Institute of Microbiology, University of Lausanne and University Hospital Center, Switzerland
| | - Lloyd Vaughan
- Institute of Veterinary Pathology, University of Zurich, Switzerland.,Pathovet AG, Tagelswangen, Switzerland
| | - Barbara Nowak
- Institute of Marine and Antarctic Studies, University of Tasmania, Newnham, Tasmania, Australia
| | - Adam Polkinghorne
- USC Animal Research Centre, Faculty of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
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6
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Blandford MI, Taylor-Brown A, Schlacher TA, Nowak B, Polkinghorne A. Epitheliocystis in fish: An emerging aquaculture disease with a global impact. Transbound Emerg Dis 2018; 65:1436-1446. [PMID: 29790651 DOI: 10.1111/tbed.12908] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/23/2018] [Accepted: 04/23/2018] [Indexed: 12/11/2022]
Abstract
Epitheliocystis is a skin and gill disease in fish caused by pathogenic intracellular bacteria. The disease has been reported in at least 90 species of marine and freshwater fish in both the southern and northern hemispheres. It affects a number of commercially important aquaculture species, including salmon, kingfish and bream. In infected fish, cysts typically develop in the gill epithelia, promoting the fusion of gill lamellae. Infections can lead to respiratory distress and death, particularly in cultured and juvenile fish with cases rarely reported in wild fish. Modern molecular techniques are challenging the conventional wisdoms regarding the epidemiology of epitheliocystis, showing now that a number of distinct bacterial pathogens from completely different phyla can cause this disease. Here, we review the state of knowledge, including updates on aetiology, host range, diagnosis and treatments. Traditionally, bacteria from the phylum Chlamydiae were the only known pathogenic agents of epitheliocystis, but aetiology is now recognized as being more complex, including a range of Proteobacteria. Notwithstanding recent advances in identifying the pathogens, the reservoirs and modes of transmission remain largely unknown. Recent genome sequencing of the growing number of epitheliocystis agents suggests that many bacteria causing this disease are unique to individual species of fish. Environmental conditions that approach or exceed animals' physiological tolerances (e.g. atypical temperature, salinity or pH levels) are thought to contribute to disease development and progression. Empirical data and evidence concerning epidemiology, aetiology and treatments are, however, in many cases limited, highlighting the need for more work to better characterize this disease across the different hosts and locales affected.
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Affiliation(s)
| | - Alyce Taylor-Brown
- USC Animal Research Centre, University of the Sunshine Coast, Maroochydore D.C., QLD, Australia
| | - Thomas A Schlacher
- USC Animal Research Centre, University of the Sunshine Coast, Maroochydore D.C., QLD, Australia.,School of Science & Engineering, University of the Sunshine Coast, Maroochydore D.C., QLD, Australia
| | - Barbara Nowak
- Institute of Marine and Antarctic Studies, University of Tasmania, Newnham, TAS, Australia
| | - Adam Polkinghorne
- USC Animal Research Centre, University of the Sunshine Coast, Maroochydore D.C., QLD, Australia
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7
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Sood N, Pradhan PK, Verma DK, Yadav MK, Dev AK, Swaminathan TR, Sood NK. Candidatus Actinochlamydia pangasiae sp. nov. (Chlamydiales, Actinochlamydiaceae), a bacterium associated with epitheliocystis in Pangasianodon hypophthalmus. JOURNAL OF FISH DISEASES 2018; 41:281-290. [PMID: 28940578 DOI: 10.1111/jfd.12711] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Chlamydial infections are recognised as causative agent of epitheliocystis, reported from over 90 fish species. In the present study, the farmed striped catfish Pangasianodon hypophthalmus (14-15 cm, 70-90 g) with a history of cumulative mortality of about 23% during June and July 2015, were brought to the laboratory. The histopathological examination of gills from the affected fish revealed presence of granular basophilic intracellular inclusions, mostly at the base of the interlamellar region and in gill filaments. A concurrent infection with Trichodina spp., Ichthyobodo spp. and Dactylogyrus spp. was observed in the gills. The presence of chlamydial DNA in the gills of affected fish was confirmed by amplification and sequencing of 16S rRNA gene. BLAST-n analysis of these amplicons revealed maximum similarity (96%) with Candidatus Actinochlamydia clariae. On the basis of phylogenetic analysis, it was inferred that the epitheliocystis agents from striped catfish were novel and belonged to the taxon Ca. Actinochlamydia. It is proposed that epitheliocystis agents from striped catfish will be named as Ca. Actinochlamydia pangasiae. The 16S rRNA gene amplicons from novel chlamydiae were labelled and linked to inclusions by in situ hybridisation. This is the first report of epitheliocystis from India in a new fish host P. hypophthalmus.
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Affiliation(s)
- N Sood
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - P K Pradhan
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - D K Verma
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - M K Yadav
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - A K Dev
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - T R Swaminathan
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, Kochi, Kerala
| | - N K Sood
- Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India
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8
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Guevara Soto M, Vidondo B, Vaughan L, Rubin JF, Segner H, Samartin S, Schmidt-Posthaus H. Investigations into the temporal development of epitheliocystis infections in brown trout: a histological study. JOURNAL OF FISH DISEASES 2017; 40:811-819. [PMID: 27670837 DOI: 10.1111/jfd.12562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/30/2016] [Accepted: 08/30/2016] [Indexed: 06/06/2023]
Abstract
Epitheliocystis in Swiss brown trout (Salmo trutta) is a chlamydial infection, mainly caused by Candidatus Piscichlamydia salmonis and Candidatus Clavichlamydia salmonicola. To gain a better understanding of the temporal development of infections in wild brown trout, we investigated epitheliocystis infections during the course of the summer and autumn months of a single year (2015), and compared this to sampling points over the span of the years 2012-2014. The survey focused on tributaries (Venoge and Boiron) of the Rhone flowing in to Lake Geneva. When evaluated histologically, epitheliocystis infections were found throughout the period of investigation with the exception of the month of June. Fifty to 86 animals per sampling were investigated. Highest prevalence and infection intensities were seen in September. A correlation between epitheliocystis infection and water temperatures was not evident. Interyear comparison revealed consistent levels of prevalence and infection intensities in late summer. The absence of infections in June, combined with the consistent interyear results, indicates seasonal fluctuation of epitheliocystis infections in brown trout with a reservoir persisting during winter months from which infections can re-initiate each year. This could either be at levels below detection limits within the brown trout population itself or in an alternative host.
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Affiliation(s)
- M Guevara Soto
- Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
| | - B Vidondo
- Institute of Veterinary Public Health, University of Bern, Bern, Switzerland
| | - L Vaughan
- Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland
| | - J-F Rubin
- Fondation de la Maison de la Rivière, Tolochenaz, Switzerland
| | - H Segner
- Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
| | - S Samartin
- Institute of Veterinary Public Health, University of Bern, Bern, Switzerland
| | - H Schmidt-Posthaus
- Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
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9
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Seth-Smith HMB, Katharios P, Dourala N, Mateos JM, Fehr AGJ, Nufer L, Ruetten M, Guevara Soto M, Vaughan L. Ca. Similichlamydia in Epitheliocystis Co-infection of Gilthead Seabream Gills: Unique Morphological Features of a Deep Branching Chlamydial Family. Front Microbiol 2017; 8:508. [PMID: 28424665 PMCID: PMC5371595 DOI: 10.3389/fmicb.2017.00508] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/13/2017] [Indexed: 12/01/2022] Open
Abstract
The Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) bacterial superphylum constitutes a broad range of organisms with an intriguing array of ultrastructural morphologies, including intracellular membranes and compartments and their corresponding complex genomes encoding these forms. The phylum Chlamydiae are all obligate intracellular bacteria and, although much is already known of their genomes from various families and how these regulate the various morphological forms, we know remarkably little about what is likely the deepest rooting clade of this phylum, which has only been found to contain pathogens of marine and fresh water vertebrates. The disease they are associated with is called epitheliocystis; however, analyses of the causative agents is hindered by an inability to cultivate them for refined in vitro experimentation. For this reason, we have developed tools to analyse both the genomes and the ultrastructures of bacteria causing this disease, directly from infected tissues. Here we present structural data for a member of the family Ca. Similichlamydiaceae from this deep-rooted clade, which we have identified using molecular tools, in epitheliocystis lesions of gilthead seabream (Sparus aurata) in Greece. We present evidence that the chlamydial inclusions appear to develop in a perinuclear location, similar to other members of the phylum and that a chlamydial developmental cycle is present, with chlamydial forms similar to reticular bodies (RBs) and elementary bodies (EBs) detected. Division of the RBs appeared to follow a budding process, and larger RBs with multiple condensed nucleoids were detected using both transmission electron microscopy (TEM) and by focused-ion beam, scanning electron microscopy (FIB-SEM). As model hosts, fish offer many advantages for investigation, and we hope by these efforts to encourage others to explore the biology of fish pathogens from the PVC.
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Affiliation(s)
- Helena M B Seth-Smith
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland.,Functional Genomics Center Zürich, University of ZürichZürich, Switzerland
| | - Pantelis Katharios
- Hellenic Center for Marine Research, Institute of Marine Biology, Biotechnology and AquacultureHeraklion, Greece
| | | | - José M Mateos
- Center for Microscopy and Image Analysis, University of ZürichZürich, Switzerland
| | - Alexander G J Fehr
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland
| | - Lisbeth Nufer
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland
| | - Maja Ruetten
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland.,Pathovet AGTagelswangen, Switzerland
| | - Maricruz Guevara Soto
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland.,Department of Infectious Diseases and Pathobiology, Centre of Fish and Wildlife Health, University of BernBern, Switzerland
| | - Lloyd Vaughan
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of ZürichZürich, Switzerland.,Pathovet AGTagelswangen, Switzerland
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10
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Taylor-Brown A, Pillonel T, Bridle A, Qi W, Bachmann NL, Miller TL, Greub G, Nowak B, Seth-Smith HMB, Vaughan L, Polkinghorne A. Culture-independent genomics of a novel chlamydial pathogen of fish provides new insight into host-specific adaptations utilized by these intracellular bacteria. Environ Microbiol 2017; 19:1899-1913. [PMID: 28205377 DOI: 10.1111/1462-2920.13694] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/02/2017] [Accepted: 02/07/2017] [Indexed: 12/12/2022]
Abstract
Several Chlamydiales families are associated with epitheliocystis, a common condition of the fish gill epithelium. These families share common ancestors with the Chlamydiaceae and environmental Chlamydiae. Due to the lack of culture systems, little is known about the biology of these chlamydial fish pathogens. We investigated epitheliocystis in cultured Orange-spotted grouper (Epinephelus coioides) from North Queensland, Australia. Basophilic inclusions were present in the gills of 22/31 fish and the presence of the chlamydial pathogen in the cysts was confirmed by in situ hybridization. Giant grouper (Epinephelus lanceolatus) cultured in the same systems were epitheliocystis free. 16S rRNA gene sequencing revealed a novel member of the Candidatus Parilichlamydiaceae: Ca. Similichlamydia epinephelii. Using metagenomic approaches, we obtained an estimated 68% of the chlamydial genome, revealing that this novel chlamydial pathogen shares a number of key pathogenic hallmarks with the Chlamydiaceae, including an intact Type III Secretion system and several chlamydial virulence factors. This provides additional evidence that these pathogenic mechanisms were acquired early in the evolution of this unique bacterial phylum. The identification and genomic characterization of Ca. S. epinephelii provides new opportunities to study the biology of distantly-related chlamydial pathogens while shining a new light on the evolution of pathogenicity of the Chlamydiaceae.
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Affiliation(s)
- Alyce Taylor-Brown
- Centre for Animal Health Innovation, Faculty of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland, 4556, Australia
| | - Trestan Pillonel
- Institute of Microbiology, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Andrew Bridle
- Institute of Marine and Antarctic Studies, University of Tasmania, Newnham, Tasmania, 7248, Australia
| | - Weihong Qi
- Functional Genomics Centre, University of Zurich, Zurich, CH-8057, Switzerland
| | - Nathan L Bachmann
- Centre for Animal Health Innovation, Faculty of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland, 4556, Australia
| | - Terrence L Miller
- Centre for Sustainable Tropical Fisheries and Aquaculture, College of Marine and Environmental Sciences, James Cook University, Cairns, Queensland, 4878, Australia
| | - Gilbert Greub
- Institute of Microbiology, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Barbara Nowak
- Institute of Marine and Antarctic Studies, University of Tasmania, Newnham, Tasmania, 7248, Australia
| | - Helena M B Seth-Smith
- Functional Genomics Centre, University of Zurich, Zurich, CH-8057, Switzerland.,Institute of Veterinary Pathology, University of Zurich, Zurich, CH-8057, Switzerland
| | - Lloyd Vaughan
- Institute of Veterinary Pathology, University of Zurich, Zurich, CH-8057, Switzerland
| | - Adam Polkinghorne
- Centre for Animal Health Innovation, Faculty of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland, 4556, Australia
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11
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Qi W, Vaughan L, Katharios P, Schlapbach R, Seth-Smith HMB. Host-Associated Genomic Features of the Novel Uncultured Intracellular Pathogen Ca. Ichthyocystis Revealed by Direct Sequencing of Epitheliocysts. Genome Biol Evol 2016; 8:1672-89. [PMID: 27190004 PMCID: PMC4943182 DOI: 10.1093/gbe/evw111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2016] [Indexed: 12/24/2022] Open
Abstract
Advances in single-cell and mini-metagenome sequencing have enabled important investigations into uncultured bacteria. In this study, we applied the mini-metagenome sequencing method to assemble genome drafts of the uncultured causative agents of epitheliocystis, an emerging infectious disease in the Mediterranean aquaculture species gilthead seabream. We sequenced multiple cyst samples and constructed 11 genome drafts from a novel beta-proteobacterial lineage, Candidatus Ichthyocystis. The draft genomes demonstrate features typical of pathogenic bacteria with an obligate intracellular lifestyle: a reduced genome of up to 2.6 Mb, reduced G + C content, and reduced metabolic capacity. Reconstruction of metabolic pathways reveals that Ca Ichthyocystis genomes lack all amino acid synthesis pathways, compelling them to scavenge from the fish host. All genomes encode type II, III, and IV secretion systems, a large repertoire of predicted effectors, and a type IV pilus. These are all considered to be virulence factors, required for adherence, invasion, and host manipulation. However, no evidence of lipopolysaccharide synthesis could be found. Beyond the core functions shared within the genus, alignments showed distinction into different species, characterized by alternative large gene families. These comprise up to a third of each genome, appear to have arisen through duplication and diversification, encode many effector proteins, and are seemingly critical for virulence. Thus, Ca Ichthyocystis represents a novel obligatory intracellular pathogenic beta-proteobacterial lineage. The methods used: mini-metagenome analysis and manual annotation, have generated important insights into the lifestyle and evolution of the novel, uncultured pathogens, elucidating many putative virulence factors including an unprecedented array of novel gene families.
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Affiliation(s)
- Weihong Qi
- Functional Genomics Center Zurich, University of Zurich, Switzerland
| | - Lloyd Vaughan
- Vetsuisse Faculty, Institute for Veterinary Pathology, University of Zurich, Switzerland
| | - Pantelis Katharios
- Hellenic Center for Marine Research, Institute of Marine Biology, Biotechnology and Aquaculture, Heraklion, Greece
| | - Ralph Schlapbach
- Functional Genomics Center Zurich, University of Zurich, Switzerland
| | - Helena M B Seth-Smith
- Functional Genomics Center Zurich, University of Zurich, Switzerland Vetsuisse Faculty, Institute for Veterinary Pathology, University of Zurich, Switzerland
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Guevara Soto M, Vaughan L, Segner H, Wahli T, Vidondo B, Schmidt-Posthaus H. Epitheliocystis Distribution and Characterization in Brown Trout (Salmo trutta) from the Headwaters of Two Major European Rivers, the Rhine and Rhone. Front Physiol 2016; 7:131. [PMID: 27148070 PMCID: PMC4834352 DOI: 10.3389/fphys.2016.00131] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/24/2016] [Indexed: 11/13/2022] Open
Abstract
We present a first description of the distribution and characterization of epitheliocystis infections in brown trout (Salmo trutta) from the upper catchments of two major European rivers, the Rhine and the Rhone. Overall, epitheliocystis was widely distributed, with 70% of the Rhine and 67% of the Rhone sites harboring epitheliocystis positive brown trout. The epitheliocystis agents Candidatus Piscichlamydia salmonis and Candidatus Clavichlamydia salmonicola could be identified in both catchments, although their relative proportions differed from site to site. Additionally, in two rivers in the Rhine catchment, a new species of Candidatus Similichlamydia was identified. Based on the histology, infection intensity, and severity of pathological changes were significantly more pronounced in mixed chlamydial infections, whereas single infections showed only low numbers of cysts and mild pathology. Infections could be found over a wide range of temperatures, which showed no correlation to infection prevalence or intensity.
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Affiliation(s)
- Maricruz Guevara Soto
- Department of Infectious Diseases and Pathobiology, Centre of Fish and Wildlife Health, University of Bern Bern, Switzerland
| | - Lloyd Vaughan
- Department of Pathobiology, Institute of Veterinary Pathology, University of Zurich Zurich, Switzerland
| | - Helmut Segner
- Department of Infectious Diseases and Pathobiology, Centre of Fish and Wildlife Health, University of Bern Bern, Switzerland
| | - Thomas Wahli
- Department of Infectious Diseases and Pathobiology, Centre of Fish and Wildlife Health, University of Bern Bern, Switzerland
| | - Beatriz Vidondo
- Department of Clinical Research and Veterinary Public Health, Veterinary Public Health Institute, University of Bern Bern, Switzerland
| | - Heike Schmidt-Posthaus
- Department of Infectious Diseases and Pathobiology, Centre of Fish and Wildlife Health, University of Bern Bern, Switzerland
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