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Weawsawang W, Homsombat T, Nuanmanee S, Saleetid N, Thawonsuwan J, Pumchan A, Hirono I, Kondo H, Unajak S. Characterization of Photobacterium damselae subsp. damselae isolated from diseased Asian seabass (Lates calcarifer) and the preliminary development of a formalin-killed cell vaccine. JOURNAL OF FISH DISEASES 2024:e13987. [PMID: 39072799 DOI: 10.1111/jfd.13987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/25/2024] [Accepted: 06/06/2024] [Indexed: 07/30/2024]
Abstract
Asian seabass (Lates calcarifer) is an economically important fish species that is widely cultivated in Thailand. However, aquaculture of Asian seabass is limited by infectious diseases. One of the most serious diseases is photobacteriosis, caused by Photobacterium damselae. Vaccination is recognized as an efficient disease prevention and pathogen control method for strengthening the aquaculture industry. To promote vaccine development, the characterization of pathogenic bacteria and their pathogenesis is required. In this study, isolates of P. damselae were obtained from commercial aquaculture farms in Thailand during 2019-2021. Analyses of 16S rRNA and the urease subunit alpha genes identified the isolates as P. damselae subsp. damselae (Phdd). Antibiotic susceptibility analyses showed that all Phdd isolates were resistant to amoxicillin (10 μg). Haemolysis and phospholipase activities were used to categorize P. damselae into three groups based on their biological activities. The pathogenicity of four candidates (SK136, PD001, PD002 and T11L) was tested in Asian seabass. Isolate SK136 showed the highest virulence, with a lethal dose (LD50) of 1.47 × 105 CFU/fish, whereas isolate PD001 did not show any virulence. Genotypic characterization, based on multi-locus sequence typing analysis, demonstrated that all candidates were novel strains with new sequence types (64, 65, 66 and 67). Preliminary vaccination using formalin-killed cells (FKCs) protected Asian seabass from artificial challenges. Taken together, these results provide fundamental knowledge for vaccine development against Phdd infection in Asian seabass.
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Affiliation(s)
- Warisara Weawsawang
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Kasetsart Vaccines and Biologics Innovation Centre, Bangkok, Thailand
| | - Theeyathart Homsombat
- Coastal Aquaculture Research and Development Division, Department of Fisheries, Ministry of Agriculture and Cooperatives, Bangkok, Thailand
| | - Saransiri Nuanmanee
- Coastal Aquaculture Research and Development Division, Department of Fisheries, Ministry of Agriculture and Cooperatives, Bangkok, Thailand
| | - Nattakan Saleetid
- Coastal Aquaculture Research and Development Division, Department of Fisheries, Ministry of Agriculture and Cooperatives, Bangkok, Thailand
| | - Jumroensri Thawonsuwan
- Coastal Aquaculture Research and Development Division, Department of Fisheries, Ministry of Agriculture and Cooperatives, Bangkok, Thailand
| | - Ansaya Pumchan
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Kasetsart Vaccines and Biologics Innovation Centre, Bangkok, Thailand
| | - Ikuo Hirono
- Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Minato-ku, Japan
| | - Hidehiro Kondo
- Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Minato-ku, Japan
| | - Sasimanas Unajak
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Kasetsart Vaccines and Biologics Innovation Centre, Bangkok, Thailand
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Triga A, Smyrli M, Katharios P. Pathogenic and Opportunistic Vibrio spp. Associated with Vibriosis Incidences in the Greek Aquaculture: The Role of Vibrio harveyi as the Principal Cause of Vibriosis. Microorganisms 2023; 11:1197. [PMID: 37317171 DOI: 10.3390/microorganisms11051197] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 04/26/2023] [Accepted: 04/28/2023] [Indexed: 06/16/2023] Open
Abstract
A monitoring program to follow vibriosis incidents in the Greek marine aquaculture was implemented over the past 13 years. 273 isolates, from various cases originating from eight regions and nine hosts, were collected and characterized. The main aquaculture species of the survey were the European seabass (Dicentrarchus labrax) and the gilthead seabream (Sparus aurata). Various species of Vibrionaceae were associated with vibriosis. Vibrio harveyi had the highest prevalence and was isolated throughout the year from all hosts. During the warm months, Vibrio harveyi prevailed with frequent co-isolations of Photobacterium damselae subsp. damselae and Vibrio alginolyticus, while during spring, other Vibrio species were more abundant, such as Vibrio lentus, Vibrio cyclitrophicus, and Vibrio gigantis. Phylogenetic analysis using the mreB gene and the metabolic fingerprint of the isolates showed great variability within the species of the collection. The severity of the disease and the frequency of outbreaks make vibriosis (that is, mainly attributed to V. harveyi) an important concern for the regional aquaculture sector.
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Affiliation(s)
- Adriana Triga
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), P.O. Box 2214, 71500 Heraklion, Greece
- Department of Biology, University of Crete, P.O. Box 1470, 71110 Heraklion, Greece
| | - Maria Smyrli
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), P.O. Box 2214, 71500 Heraklion, Greece
| | - Pantelis Katharios
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), P.O. Box 2214, 71500 Heraklion, Greece
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Rosado D, Xavier R, Cable J, Severino R, Tarroso P, Pérez-Losada M. Longitudinal sampling of external mucosae in farmed European seabass reveals the impact of water temperature on bacterial dynamics. ISME COMMUNICATIONS 2021; 1:28. [PMID: 36739461 PMCID: PMC9723769 DOI: 10.1038/s43705-021-00019-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/13/2021] [Indexed: 02/06/2023]
Abstract
Fish microbiota are intrinsically linked to health and fitness, but they are highly variable and influenced by both biotic and abiotic factors. Water temperature particularly limits bacterial adhesion and growth, impacting microbial diversity and bacterial infections on the skin and gills. Aquaculture is heavily affected by infectious diseases, especially in warmer months, and industry practices often promote stress and microbial dysbiosis, leading to an increased abundance of potentially pathogenic bacteria. In this regard, fish mucosa health is extremely important because it provides a primary barrier against pathogens. We used 16 rRNA V4 metataxonomics to characterize the skin and gill microbiota of the European seabass, Dicentrarchus labrax, and the surrounding water over 12 months, assessing the impact of water temperature on microbial diversity and function. We show that the microbiota of external mucosae are highly dynamic with consistent longitudinal trends in taxon diversity. Several potentially pathogenic genera (Aliivibrio, Photobacterium, Pseudomonas, and Vibrio) were highly abundant, showing complex interactions with other bacterial genera, some of which with recognized probiotic activity, and were also significantly impacted by changes in temperature. The surrounding water temperature influenced fish microbial composition, structure and function over time (days and months). Additionally, dysbiosis was more frequent in warmer months and during transitions between cold/warm months. We also detected a strong seasonal effect in the fish microbiota, which is likely to result from the compound action of several unmeasured environmental factors (e.g., pH, nutrient availability) beyond temperature. Our results highlight the importance of performing longitudinal studies to assess the impact of environmental factors on fish microbiotas.
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Affiliation(s)
- Daniela Rosado
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal.
| | - Raquel Xavier
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal.
| | - Jo Cable
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Ricardo Severino
- Piscicultura Vale da Lama, Sapal do Vale da Lama, Odiáxere, Lagos, Portugal
| | - Pedro Tarroso
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal
| | - Marcos Pérez-Losada
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal
- Computational Biology Institute, Department of Biostatistics and Bioinformatics, Milken Institute School of Public Health, George Washington University, Washington, DC, USA
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Zhao Z. Comparison of microbial communities and the antibiotic resistome between prawn mono- and poly-culture systems. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 207:111310. [PMID: 32937228 DOI: 10.1016/j.ecoenv.2020.111310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/01/2020] [Accepted: 09/05/2020] [Indexed: 06/11/2023]
Abstract
Antibiotic resistance genes (ARGs) in mariculture sediments pose a potential risk to public health due to their ability to transfer from environmental bacteria to human pathogens. Long term, this may reduce pathogen susceptibility to antibiotics in medical settings. In recent years, the poly-culture of multiple species has become a popular mariculture approach in China, thanks to its environmental and economic benefits. However, differences in microbial communities and antibiotic resistome between mono- and poly-culture systems are still unclear. In this study, microbial community composition and profiles of entire (microbial DNA) and mobile (plasmid and phage) ARGs in prawn mono- and poly-culture systems were investigated using metagenomics. The abundance of several viruses and human pathogens were enhanced in prawn poly-culture ponds, when compared to monoculture systems. In contrast, sediments from poly-culture systems had a lower diversity and ARG abundance when compared to mono-culture approaches. These ARG variations were predominantly related to mobile genetic elements. Prawn mariculture activities exerted a unique selectivity for ARGs in plasmids, and this selectivity was not influenced by culture methods. The findings of this study have important implications for the selection of mariculture systems in preventing pollution with ARGs.
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Affiliation(s)
- Zelong Zhao
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, Liaoning, PR China.
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El-Son MAM, Elbahnaswy S, Ibrahim I. Molecular and histopathological characterization of Photobacterium damselae in naturally and experimentally infected Nile tilapia (Oreochromis niloticus). JOURNAL OF FISH DISEASES 2020; 43:1505-1517. [PMID: 32984991 DOI: 10.1111/jfd.13251] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
Mass mortality has occurred among cultured Nile tilapia, Oreochromis niloticus, on fish farms in Manzala, Dakahlia province, Egypt, in the summer season, 2019. Moribund fish were reported with deep ulcers, septicaemic lesions and sampled for bacterial isolation. In this study, most isolates were subjected to bacteriological examination, antibiotic sensitivity test, 16S rRNA gene sequencing and histopathological examination. Following isolate identification, intraperitoneal challenge of Nile tilapia with a bacterial suspension 2 × 106 CFU/ml was performed. Samples from liver, spleen and kidney were collected for histological and biochemical analysis. The results showed a high similarity (99%) to Photobacterium damselae strains using phylogenetic analysis of 16S rRNA. P. damselae exhibited resistance to amoxicillin and erythromycin, as well it was highly sensitive to chloramphenicol and doxycycline. Moreover, haemorrhage, oedema, hemosiderosis and melanomacrophage activation in the liver and head kidney of infected fish were detected by light and electron microscopy. Also, significant higher levels of CAT and SOD in the spleen and head kidney, as well as the serum levels of NO were observed in experimentally challenged O. niloticus, compared to the control fish. Our data identified P. damselae for the first time from infected Nile tilapia, describing its sensitivity to a variety of antibiotics, histopathological alterations and oxidative stress impact, and it could be useful indicators for understanding P. damselae pathogenesis, which might provide a preventive efficacy for P. damselae.
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Affiliation(s)
- Mai A M El-Son
- Department of Internal Medicine, Infectious and Fish Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Samia Elbahnaswy
- Department of Internal Medicine, Infectious and Fish Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Iman Ibrahim
- Department of Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
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Matanza XM, Osorio CR. Exposure of the Opportunistic Marine Pathogen Photobacterium damselae subsp. damselae to Human Body Temperature Is a Stressful Condition That Shapes the Transcriptome, Viability, Cell Morphology, and Virulence. Front Microbiol 2020; 11:1771. [PMID: 32849395 PMCID: PMC7396505 DOI: 10.3389/fmicb.2020.01771] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 07/06/2020] [Indexed: 01/21/2023] Open
Abstract
Photobacterium damselae subsp. damselae (Pdd), an important pathogen for marine animals, is also an opportunistic human pathogen that can cause fatal necrotizing fasciitis. The regulatory changes triggered by the temperature shift experienced by this marine pathogen upon entering the human body, are completely unknown. Here we report an RNA-seq approach combined with phenotypical assays to study the response of Pdd to cultivation at 37°C in comparison to 25°C. We found that cultivation of a Pdd highly virulent strain for fish and mice, RM-71, at 37°C, initially enhanced bacterial growth in comparison to 25°C as evidenced by the increase in optical density. However, cells were found to undergo a progressive loss of viability after 6 h cultivation at 37°C, and no viable cells could be detected from 30 h cultures at 37°C. In contrast, at 25°C, viable cell counts achieved the highest values at 30 h cultivation. Cells grown at 25°C showed normal rod morphology by scanning electron microscopy analysis whereas cells grown at 37°C exhibited chain-like structures and aberrant long shapes suggesting a defect in daughter cell separation and in septum formation. Cells grown at 37°C also exhibited reduced tolerance to benzylpenicillin. Using a RNA-seq approach we discovered that growth at 37°C triggered a heat-shock response, whereas genes involved in motility and virulence were repressed including iron acquisition systems, the type two secretion system, and damselysin toxin, a major virulence factor of Pdd. Human isolates did not exhibit advantage growing at 37°C compared to fish isolates, and comparative genomics did not reveal gene markers specific of human isolates, suggesting that any Pdd genotype existing in the marine environment might potentially cause disease in humans. Altogether, these data indicate that the potential of Pdd to cause disease in humans is an accidental condition rather than a selected trait, and that human body temperature constitutes a stressful condition for Pdd. This study provides the first transcriptome profile of Pdd exposed at human body temperature, and unveils a number of candidate molecular targets for prevention and control of human infections caused by this pathogen.
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Affiliation(s)
- Xosé M Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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Yu Y, Zhang Z, Wang Y, Liao M, Rong X, Li B, Wang K, Chen J, Zhang H. Complete Genome Sequence of Photobacterium damselae Subsp. damselae Strain SSPD1601 Isolated from Deep-Sea Cage-Cultured Sebastes schlegelii with Septic Skin Ulcer. Int J Genomics 2019; 2019:4242653. [PMID: 31093490 PMCID: PMC6481104 DOI: 10.1155/2019/4242653] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/16/2019] [Accepted: 02/20/2019] [Indexed: 11/21/2022] Open
Abstract
Photobacterium damselae subsp. damselae (PDD) is a Gram-negative bacterium that can infect a variety of aquatic organisms and humans. Based on an epidemiological investigation conducted over the past 3 years, PDD is one of the most important pathogens causing septic skin ulcer in deep-sea cage-cultured Sebastes schlegelii in the Huang-Bohai Sea area and present throughout the year with high abundance. To further understand the pathogenicity of this species, the pathogenic properties and genome of PDD strain SSPD1601 were analyzed. The results revealed that PDD strain SSPD1601 is a rod-shaped cell with a single polar flagellum, and the clinical symptoms were replicated during artificial infection. The SSPD1601 genome consists of two chromosomes and two plasmids, totaling 4,252,294 bp with 3,751 coding sequences (CDSs), 196 tRNA genes, and 47 rRNA genes. Common virulence factors including flagellin, Fur, RstB, hcpA, OMPs, htpB-Hsp60, VasK, and vgrG were found in strain SSPD1601. Furthermore, SSPD1601 is a pPHDD1-negative strain containing the hemolysin gene hlyAch and three putative hemolysins (emrA, yoaF, and VPA0226), which are likely responsible for the pathogenicity of SSPD1601. The phylogenetic analysis revealed SSPD1601 to be most closely related to Phdp Wu-1. In addition, the antibiotic resistance phenotype indicated that SSPD1601 was not sensitive to ceftazidime, pipemidic, streptomycin, cefalexin, bacitracin, cefoperazone sodium, acetylspiramycin, clarithromycin, amikacin, gentamycin, kanamycin, oxacillin, ampicillin, and trimethoprim-sulfamethoxazole, but only the bacitracin resistance gene bacA was detected based on Antibiotic Resistance Genes Database. These results expand our understanding of PDD, setting the stage for further studies of its pathogenesis and disease prevention.
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Affiliation(s)
- Yongxiang Yu
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
| | - Zheng Zhang
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Yingeng Wang
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Meijie Liao
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaojun Rong
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Bin Li
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
| | - Kai Wang
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
| | - Jing Chen
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
| | - Hao Zhang
- Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao 266071, China
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Matanza XM, Osorio CR. Transcriptome changes in response to temperature in the fish pathogen Photobacterium damselae subsp. damselae: Clues to understand the emergence of disease outbreaks at increased seawater temperatures. PLoS One 2018; 13:e0210118. [PMID: 30596794 PMCID: PMC6312309 DOI: 10.1371/journal.pone.0210118] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/17/2018] [Indexed: 01/22/2023] Open
Abstract
The marine bacterium Photobacterium damselae subsp. damselae (Pdd) is a generalist and facultative pathogen that causes disease in a wide range of marine animals including fish species of importance in aquaculture. Disease outbreaks in fish farms have been correlated with an increased water temperature during summer months. In this study, we have used RNA sequencing to analyze the transcriptome of Pdd RM-71 cultured at two different temperatures, which simulated temperature conditions experienced during free swimming lifestyle at mid latitudes in winter months (15°C) and during outbreaks in aquaculture in warm summer months (25°C). The enhanced bacterial growth of Pdd observed at 25°C in comparison to 15°C suggests that an elevated seawater temperature contributes to the build-up of a sufficient bacterial population to cause disease. In comparison to growth at 15°C, growth at 25°C resulted in the upregulation of genes involved in DNA synthesis, nutrient uptake, chemotaxis, flagellar motility, secretion systems and antimicrobial resistance. Plasmid-encoded virulence factors, which include a putative adhesin/invasin OmpU, a transferrin receptor and a serum resistance protein, were also upregulated. Transcription factor RpoS, genes involved in cold shock response, modulation of cell envelope and amino acid metabolism, as well as genes of yet unknown function were downregulated at 25°C. Notably, the gene encoding damselysin cytotoxin (Dly) was among the most highly transcribed genes at the two assayed temperatures, at levels comparable to the most highly expressed housekeeping genes. This study contributes to our understanding of the regulatory networks and biology of a generalist marine bacterial pathogen, and provides evidence that temperature regulates multiple physiological and virulence-related functions in Pdd.
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Affiliation(s)
- Xosé M. Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Carlos R. Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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Terceti MS, Vences A, Matanza XM, Dalsgaard I, Pedersen K, Osorio CR. Molecular Epidemiology of Photobacterium damselae subsp. damselae Outbreaks in Marine Rainbow Trout Farms Reveals Extensive Horizontal Gene Transfer and High Genetic Diversity. Front Microbiol 2018; 9:2155. [PMID: 30283411 PMCID: PMC6156455 DOI: 10.3389/fmicb.2018.02155] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 08/22/2018] [Indexed: 12/13/2022] Open
Abstract
The marine bacterium Photobacterium damselae subsp. damselae is a pathogen for a variety of marine animals, as well as for humans, and is nowadays considered an emerging pathogen for fish of importance in marine aquaculture. Recent studies have suggested that outbreaks in fish farms are caused by multiclonal populations of this subspecies that exist in the environment. Here, we report the study of a collection of 31 strains isolated during the course of disease outbreaks in marine rainbow trout farms in Denmark in 1994, 1995, and 2006, respectively. A phylogenetic analysis based on the toxR gene sequence, and the screening of virulence-related genes uncovered a high genetic heterogeneity, even among strains isolated from the same fish farm at the same time. Moreover, comparative analysis of the whole genome sequences of four selected strains revealed a large number of differentially occurring genes, which included virulence genes, pPHDD1 plasmid, polysaccharide synthesis gene clusters, CRISPR-Cas systems and putative new mobile genetic elements. This study provides sound evidence that P. damselae subsp. damselae outbreaks in Danish rainbow trout farms were caused by multiclonal populations and that horizontal gene transfer constitutes a strong driving force in the generation of intraspecific diversity in this pathogen.
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Affiliation(s)
- Mateus S. Terceti
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Ana Vences
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Xosé M. Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Inger Dalsgaard
- National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Karl Pedersen
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Carlos R. Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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Osorio CR, Vences A, Matanza XM, Terceti MS. Photobacterium damselae subsp. damselae, a generalist pathogen with unique virulence factors and high genetic diversity. J Bacteriol 2018; 200:e00002-18. [PMID: 29440249 PMCID: PMC6040198 DOI: 10.1128/jb.00002-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Photobacterium damselae subsp. damselae causes vibriosis in a variety of marine animals, including fish species of importance in aquaculture. It also may cause wound infections in humans that can progress into a fatal outcome. Two major virulence factors are encoded within the large conjugative plasmid pPHDD1: the phospholipase-D damselysin (Dly) and the pore-forming toxin Phobalysin P (PhlyP). The two toxins exert hemolytic and cytolytic activity in a synergistic manner. Albeit PhlyP has close homologues in many Vibrio species, it has unique features that differentiate it from related toxins. Dly phospholipase constitutes a singular trait of P. damselae subsp. damselae among the Vibrionaceae, although related toxins are found in members of the Aeromonadaceae Fish farm outbreaks can also be caused by plasmidless strains. Such observation led to the characterization of two ubiquitous, chromosome-encoded toxins with lesser cytolytic activity: the pore forming-toxin Phobalysin C (PhlyC) and the phospholipase-hemolysin PlpV. Special attention deserves the high genetic diversity of this pathogen, with a number of strain-specific features including the cell envelope polysaccharide synthesis clusters. Fish outbreaks are likely caused by multiclonal populations which contain both plasmidless and pPHDD1-harbouring isolates, and not by well-adapted clonal complexes. Still, among such a genetic heterogeneity, it is feasible to identify conserved weak points in the biology of this bacterium: the two-component regulatory system RstAB (CarSR) was found to be necessary for maximal production of virulence factors and its inactivation severely impaired virulence.
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Affiliation(s)
- Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
| | - Ana Vences
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
| | - Xosé Manuel Matanza
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
| | - Mateus S Terceti
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
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