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Avendaño-Herrera R, Lopez P, Echeverría-Bugueño M, Araya-León H, Irgang R. Characterization of Tenacibaculum maritimum isolated from diseased salmonids farmed in Chile reveals high serological and genetic heterogeneity. JOURNAL OF FISH DISEASES 2024; 47:e13965. [PMID: 38801516 DOI: 10.1111/jfd.13965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/13/2024] [Accepted: 05/16/2024] [Indexed: 05/29/2024]
Abstract
The diversity of Tenacibaculum maritimum in Chile remains poorly understood, particularly in terms of antigenic and genetic diversity. This information is crucial for the future development of a vaccine against tenacibaculosis and would increase understanding of this important fish pathogen. With this aim, the biochemical, antigenic, and genetic characteristics were analysed for 14 T. maritimum isolates, recovered from diseased Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) farmed in Chile between 1998 and 2022. Biochemical analysis showed a homogeneity among all the Chilean T. maritimum isolates and all four other strains included for comparison purposes. Serological characterization using dot-blot assaying revealed antigenic heterogeneity with the use of unabsorbed antisera. The majority of isolates showed cross-reactions, identifying three main serological patterns. When the PCR-based serotyping scheme was performed, the existence of antigenic heterogeneity was confirmed. Four Atlantic salmon isolates were 4-0; and most isolates, including the rainbow trout isolate, were 3-1 (n = 9). A turbot (Scophthalmus maximus) isolate was 1-0. Using an existing Multilocus Sequence Typing system, two newly identified sequence types (ST193 and ST198) in the database were detected. ST193 encompassed nine isolates obtained from Atlantic salmon and rainbow trout, while ST198 regrouped four isolates, all retrieved from diseased Atlantic salmon in 2022. These findings highlight significant antigenic and genetic diversity among the Chilean isolates. This information is useful for epizootiology and the selection of suitable candidate strain(s) for vaccine development against tenacibaculosis caused by T. maritimum in Chilean salmon farming.
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Affiliation(s)
- Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
| | - Pierre Lopez
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Macarena Echeverría-Bugueño
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Henry Araya-León
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
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Avendaño-Herrera R, Saldarriaga-Córdoba M, Echeverría-Bugueño M, Irgang R. In vitro phenotypic evidence for the utilization of iron from different sources and siderophores production in the fish pathogen Tenacibaculum dicentrarchi. JOURNAL OF FISH DISEASES 2023; 46:1001-1012. [PMID: 37309564 DOI: 10.1111/jfd.13820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/14/2023]
Abstract
Iron uptake during infection is an essential pathogenicity factor of several bacteria, including Tenacibaculum dicentrarchi, an emerging pathogen for salmonid and red conger eel (Genypterus chilensis) farms in Chile. Iron-related protein families were recently found in eight T. dicentrarchi genomes, but biological studies have not yet confirmed functions. The investigation reported herein clearly demonstrated for the first time that T. dicentrarchi possesses different systems for iron acquisition-one involving the synthesis of siderophores and another allowing for the utilization of heme groups. Using 38 isolates of T. dicentrarchi and the type strain CECT 7612T , all strains grew in the presence of the chelating agent 2.2'-dipyridyl (from 50 to 150 μM) and produced siderophores on chrome azurol S plates. Furthermore, 37 of the 38 T. dicentrarchi isolates used at least four of the five iron sources (i.e. ammonium iron citrate, ferrous sulfate, iron chloride hexahydrate, haemoglobin and/or hemin) when added to iron-deficient media, although the cell yield was less when using hemin. Twelve isolates grew in the presence of hemin, and 10 of them used only 100 μM. Under iron-supplemented or iron-restricted conditions, whole cells of three isolates and the type strain showed at least one membrane protein induced in iron-limiting conditions (c.a. 37.9 kDa), regardless of the isolation host. All phenotypic results were confirmed by in-silico genomic T. dicentrarchi analysis. Future studies will aim to establish a relationship between iron uptake ability and virulence in T. dicentrarchi through in vivo assays.
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Affiliation(s)
- Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
| | - Mónica Saldarriaga-Córdoba
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación en Recursos Naturales y Sustentabilidad, Universidad Bernardo O'Higgins, Santiago, Chile
| | - Macarena Echeverría-Bugueño
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
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Nowlan JP, Sies AN, Britney SR, Cameron ADS, Siah A, Lumsden JS, Russell S. Genomics of Tenacibaculum Species in British Columbia, Canada. Pathogens 2023; 12:pathogens12010101. [PMID: 36678448 PMCID: PMC9864904 DOI: 10.3390/pathogens12010101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Tenacibaculum is a genus of Gram-negative filamentous bacteria with a cosmopolitan distribution. The research describing Tenacibaculum genomes stems primarily from Norway and Chile due to their impacts on salmon aquaculture. Canadian salmon aquaculture also experiences mortality events related to the presence of Tenacibaculum spp., yet no Canadian Tenacibaculum genomes are publicly available. Ribosomal DNA sequencing of 16S and four species-specific 16S quantitative-PCR assays were used to select isolates cultured from Atlantic salmon with mouthrot in British Columbia (BC), Canada. Ten isolates representing four known and two unknown species of Tenacibaculum were selected for shotgun whole genome sequencing using the Oxford Nanopore's MinION platform. The genome assemblies achieved closed circular chromosomes for seven isolates and long contigs for the remaining three isolates. Average nucleotide identity analysis identified T. ovolyticum, T. maritimum, T. dicentrarchi, two genomovars of T. finnmarkense, and two proposed novel species T. pacificus sp. nov. type strain 18-2881-AT and T. retecalamus sp. nov. type strain 18-3228-7BT. Annotation in most of the isolates predicted putative virulence and antimicrobial resistance genes, most-notably toxins (i.e., hemolysins), type-IX secretion systems, and oxytetracycline resistance. Comparative analysis with the T. maritimum type-strain predicted additional toxins and numerous C-terminal secretion proteins, including an M12B family metalloprotease in the T. maritimum isolates from BC. The genomic prediction of virulence-associated genes provides important targets for studies of mouthrot disease, and the annotation of the antimicrobial resistance genes provides targets for surveillance and diagnosis in veterinary medicine.
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Affiliation(s)
- Joseph P. Nowlan
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Correspondence:
| | - Ashton N. Sies
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Scott R. Britney
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Andrew D. S. Cameron
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Ahmed Siah
- BC Center for Aquatic Health Sciences, Campbell River, BC V9W 2C2, Canada
| | - John S. Lumsden
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Spencer Russell
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
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Mabrok M, Algammal AM, Sivaramasamy E, Hetta HF, Atwah B, Alghamdi S, Fawzy A, Avendaño-Herrera R, Rodkhum C. Tenacibaculosis caused by Tenacibaculum maritimum: Updated knowledge of this marine bacterial fish pathogen. Front Cell Infect Microbiol 2023; 12:1068000. [PMID: 36683696 PMCID: PMC9853564 DOI: 10.3389/fcimb.2022.1068000] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 11/28/2022] [Indexed: 01/07/2023] Open
Abstract
Tenacibaculosis occurs due to the marine bacterial pathogen Tenacibaculum maritimum. This ulcerative disease causes high mortalities for various marine fish species worldwide. Several external clinical signs can arise, including mouth erosion, epidermal ulcers, fin necrosis, and tail rot. Research in the last 15 years has advanced knowledge on the traits and pathogenesis mechanisms of T. maritimum. Consequently, significant progress has been made in defining the complex host-pathogen relationship. Nevertheless, tenacibaculosis pathogenesis is not yet fully understood. Continued research is urgently needed, as demonstrated by recent reports on the re-emerging nature of tenacibaculosis in salmon farms globally. Current sanitary conditions compromise the development of effective alternatives to antibiotics, in addition to hindering potential preventive measures against tenacibaculosis. The present review compiles knowledge of T. maritimum reported after the 2006 review by Avendaño-Herrera and colleagues. Essential aspects are emphasized, including antigenic and genomic characterizations and molecular diagnostic procedures. Further summarized are the epidemiological foundations of the T. maritimum population structure and elucidations as to the virulence mechanisms of pathogenic isolates, as found using biological, microbiological, and genomic techniques. This comprehensive source of reference will undoubtable serve in tenacibaculosis prevention and control within the marine fish farming industry. Lastly, knowledge gaps and valuable research areas are indicated as potential guidance for future studies.
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Affiliation(s)
- Mahmoud Mabrok
- Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt,Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand,Center of Excellence in Fish Infectious Diseases (CE FID), Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Abdelazeem M. Algammal
- Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
| | - Elayaraja Sivaramasamy
- Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand,Center of Excellence in Fish Infectious Diseases (CE FID), Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Helal F. Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assuit University, Assuit, Egypt
| | - Banan Atwah
- Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Saad Alghamdi
- Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Aml Fawzy
- Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand,Directorate of Veterinary Medicine, Ismailia, Egypt
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña del Mar, Chile,Interdisciplinary Center for Aquaculture Research (INCAR), Viña del Mar, Chile,Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile,*Correspondence: Channarong Rodkhum, ; Ruben Avendaño-Herrera, ;
| | - Channarong Rodkhum
- Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand,Center of Excellence in Fish Infectious Diseases (CE FID), Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand,*Correspondence: Channarong Rodkhum, ; Ruben Avendaño-Herrera, ;
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Avendaño‐Herrera R, Olsen AB, Saldarriaga‐Cordoba M, Colquhoun DJ, Reyes V, Rivera‐Bohle J, Duchaud E, Irgang R. Isolation, identification, virulence potential, and genomic features of
Tenacibaculum piscium
isolates recovered from Chilean salmonids. Transbound Emerg Dis 2022; 69:e3305-e3315. [DOI: 10.1111/tbed.14606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Ruben Avendaño‐Herrera
- Universidad Andrés Bello Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola Facultad de Ciencias de la Vida Viña del Mar Chile
- Centro FONDAP INCAR Universidad Andrés Bello Viña del Mar Chile
| | - Anne Berit Olsen
- Section of Aquatic Biosecurity Research Norwegian Veterinary Institute Bergen Norway
| | - Mónica Saldarriaga‐Cordoba
- Centro FONDAP INCAR Universidad Andrés Bello Viña del Mar Chile
- CIRENYS Universidad Bernardo O'Higgins Santiago Chile
| | | | - Víctor Reyes
- Farmacología en Aquacultura Veterinaria FAV S.A Puerto Varas Chile
| | | | - Eric Duchaud
- UMR 0892‐Virologie et Immunologie Moléculaires Université Paris‐Saclay UVSQ INRAE Jouy‐en‐Josas France
| | - Rute Irgang
- Centro FONDAP INCAR Universidad Andrés Bello Viña del Mar Chile
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Irgang R, Avendaño-Herrera R. Evaluation of the in vitro susceptibility of Tenacibaculum dicentrarchi to tiamulin using minimum inhibitory concentration tests. JOURNAL OF FISH DISEASES 2022; 45:795-799. [PMID: 35262919 DOI: 10.1111/jfd.13604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 06/14/2023]
Abstract
Tenacibaculosis caused by Tenacibaculum dicentrarchi is the third most important bacterial fish infection affecting the Chilean salmon industry. Losses to this disease are most frequently controlled by treatments with florfenicol and oxytetracycline. However, recent tenacibaculosis outbreaks were controlled through the extra-label, oral administration of tiamulin, resulting in high treatment efficiency. In this study, we present an analysis of susceptibility patterns of 32 T. dicentrarchi isolates and the type strain CECT 7612T to tiamulin by determining the minimum inhibitory concentrations (MICs) according to the procedures recommended by the Clinical and Laboratory Standard Institute, but fixing incubation temperature to the more appropriate for the growth of T. dicentrarchi (18 ºC). The MICs of the T. dicentrarchi isolates were unimodally distributed (0.06-1.0 µg/ml range), while the CECT 7612T strain presented an MIC of 0.5 μg/ml. Calculations using Normalized Resistance Interpretation provided epidemiological cut-off values of ≤1.0 µg/ml, with the 33 T. dicentrarchi classified as wild type. In Chile, tiamulin is authorized for use in other livestock species, but application in salmonids is extra-label. Our presented in vitro results suggest that tiamulin is a viable alternative to florfenicol, specifically as tiamulin requires comparatively lower concentrations to inhibit T. dicentrarchi. Considering that tiamulin is also exclusively for veterinary use, is classified as "least important" by the World Health Organization and has not resulted in the development of bacterial resistance, pharmaceutical companies should be requested to register tiamulin and provide alternative antimicrobial treatments for the salmonid industry.
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Affiliation(s)
- Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Viña del Mar, Chile
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
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Saldarriaga-Córdoba M, Irgang R, Avendaño-Herrera R. Comparison between genome sequences of Chilean Tenacibaculum dicentrarchi isolated from red conger eel (Genypterus chilensis) and Atlantic salmon (Salmo salar) focusing on bacterial virulence determinants. JOURNAL OF FISH DISEASES 2021; 44:1843-1860. [PMID: 34369594 DOI: 10.1111/jfd.13503] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 06/13/2023]
Abstract
Tenacibaculum dicentrarchi is an emerging pathogen for salmonid cultures and red conger eel (Genypterus chilensis) in Chile, causing high economic losses not only in Chile but also to the global salmon industry. Infected fish show severe gross skin lesions that are sometimes accompanied by bone exposure. Despite pathogenicity demonstrated by Koch's postulates, no knowledge is currently available regarding the virulence machinery of T. dicentrarchi strains. Comparisons between the genome sequences of the eight T. dicentrarchi strains obtained from G. chilensis and Atlantic salmon (Salmo salar) provide insights on the existence of genomic diversity within this bacterium. The T. dicentrarchi type strain 3509T was used as a reference genome. Depending on the T. dicentrarchi strain, the discovered diversity included genes associated with iron acquisition mechanisms, copper homeostasis encoding, resistance to tetracycline and fluoroquinolones, pathogenic genomic islands and phages. Interestingly, genes encoding the T9SS membrane protein PorP/SprF were retrieved in all of the analysed T. dicentrarchi strains, regardless of the host fish (i.e. red conger eel or Atlantic salmon). However, the T6SS core component protein VgrG was identified in only one Atlantic salmon strain. Three types of peptidase genes and proteins associated with quorum sensing were detected in all of the T. dicentrarchi strains. In turn, all eight strains presented a total of 17 proteins associated with biofilm formation, which was previously confirmed through physiological studies. This comparative analysis will help elucidate and describe the genes and pathways that are likely involved in the virulence process of T. dicentrarchi. All or part of these predicted genes could aid the pathogen during the infective process in fish, making further physiological research necessary for clarification.
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Affiliation(s)
- Mónica Saldarriaga-Córdoba
- Centro de Investigación en Recursos Naturales y Sustentabilidad, Universidad Bernardo O'Higgins, Santiago, Chile
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
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Valdes S, Irgang R, Barros MC, Ilardi P, Saldarriaga-Córdoba M, Rivera-Bohle J, Madrid E, Gajardo-Córdova J, Avendaño-Herrera R. First report and characterization of Tenacibaculum maritimum isolates recovered from rainbow trout (Oncorhynchus mykiss) farmed in Chile. JOURNAL OF FISH DISEASES 2021; 44:1481-1490. [PMID: 34061372 DOI: 10.1111/jfd.13466] [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: 04/23/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 06/12/2023]
Abstract
The present study reports on the first isolation of Tenacibaculum maritimum in rainbow trout (Oncorhynchus mykiss) farmed in Chile. In March 2020, two cages raising rainbow trout (~250 g) in the Los Lagos Region suffered a disease outbreak. In total, 17,554 fish died (3.5%-4.8% accumulated mortality). Microbiological analysis of the diseased fish obtained two representative isolates (i.e. Tm-035 and Tm-036). These were obtained from the external gross skin lesions-typical of tenacibaculosis-of two fish. Phenotyping, PCR tests and sequencing of the 16S rRNA and housekeeping genes confirmed the isolates as T. maritimum. The pathogenic potential of Tm-035 was further assessed by bath challenging Atlantic salmon (Salmo salar), which killed 70 ± 15% of fish within 11 days. Dead fish presented the same external clinical signs as did the farmed rainbow trout specimens. This research further broadens the known host distribution of this pathogen. Furthermore, the virulence experiments demonstrated that T. maritimum does not have a specific host. Additional studies are needed to evaluate the risk of T. maritimum for the O. mykiss farming industry.
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Affiliation(s)
- Sara Valdes
- Farmacología en Aquacultura Veterinaria FAV S.A, Puerto Varas, Chile
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Universidad Andrés Bello, Viña del Mar, Chile
| | - María C Barros
- Farmacología en Aquacultura Veterinaria FAV S.A, Puerto Varas, Chile
| | - Pedro Ilardi
- Farmacología en Aquacultura Veterinaria FAV S.A, Puerto Varas, Chile
| | - Mónica Saldarriaga-Córdoba
- Centro de Investigación en Recursos Naturales y Sustentabilidad, Universidad Bernardo O'Higgins, Santiago, Chile
| | | | - Enrique Madrid
- Farmacología en Aquacultura Veterinaria FAV S.A, Puerto Varas, Chile
| | | | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP, Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Valparaíso, Chile
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