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Eckstrand CD, Torrevillas BK, Wolking RM, Bradway DS, Warg JV, Clayton RD, Williams LB, Pessier AP, Reno JL, McMenamin-Snekvik KM, Thompson J, Baszler T, Snekvik KR. Investigation of laboratory methods for characterization of aquatic viruses in fish infected experimentally with infectious salmon anemia virus. J Vet Diagn Invest 2024; 36:319-328. [PMID: 37203453 PMCID: PMC11110770 DOI: 10.1177/10406387231173332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023] Open
Abstract
Rapid growth in aquaculture has resulted in high-density production systems in ecologically and geographically novel conditions in which the emergence of diseases is inevitable. Well-characterized methods for detection and surveillance of infectious diseases are vital for rapid identification, response, and recovery to protect economic and food security. We implemented a proof-of-concept approach for virus detection using a known high-consequence fish pathogen, infectious salmon anemia virus (ISAV), as the archetypal pathogen. In fish infected with ISAV, we integrated histopathology, virus isolation, whole-genome sequencing (WGS), electron microscopy (EM), in situ hybridization (ISH), and reverse transcription real-time PCR (RT-rtPCR). Fresh-frozen and formalin-fixed tissues were collected from virus-infected, control, and sham-infected Atlantic salmon (Salmo salar). Microscopic differences were not evident between uninfected and infected fish. Viral cytopathic effect was observed in cell cultures inoculated with fresh-frozen tissue homogenates from 3 of 3 ISAV-infected and 0 of 4 uninfected or sham-infected fish. The ISAV genome was detected by shotgun metagenomics in RNA extracted from the medium from 3 of 3 inoculated cell cultures, 3 of 3 infected fish, and 0 of 4 uninfected or sham-infected fish, yielding sufficient coverage for de novo assembly. An ISH probe against ISAV revealed ISAV genome in multiple organs, with abundance in renal hematopoietic tissue. Virus was detected by RT-rtPCR in gill, heart, kidney, liver, and spleen. EM and metagenomic WGS from tissues were challenging and unsuccessful. Our proof-of-concept methodology has promise for detection and characterization of unknown aquatic pathogens and also highlights some associated methodology challenges that require additional investigation.
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Affiliation(s)
- Chrissy D. Eckstrand
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Brandi K. Torrevillas
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Rebecca M. Wolking
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Daniel S. Bradway
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Janet V. Warg
- National Veterinary Services Laboratories, U.S. Department of Agriculture, Ames, IA, USA
| | - Richard D. Clayton
- National Veterinary Services Laboratories, U.S. Department of Agriculture, Ames, IA, USA
| | - Laura B. Williams
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Allan P. Pessier
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Joetta Lynn Reno
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | | | - Jim Thompson
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Timothy Baszler
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
| | - Kevin R. Snekvik
- Washington Animal Disease Diagnostic Laboratory, Washington State University, Pullman, WA, USA
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2
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Aunsmo A, Martinsen L, Bruheim T, Sekkelsten-Kindt MM, Sandtrø A, Gaasø S, Braaen S, Rimstad E. Triploid Atlantic salmon (Salmo salar) may have increased risk of primary field outbreaks of infectious salmon anaemia. JOURNAL OF FISH DISEASES 2022; 45:1733-1743. [PMID: 35914108 PMCID: PMC9805046 DOI: 10.1111/jfd.13695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 07/17/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
The impact that escaped farmed fish may have on wild populations is of major concern for Atlantic salmon (Salmo salar) farming. Triploid fish, being infertile, were originally introduced to mitigate the genetic impact of escaped fish. In the recent years, an increase in the number of infectious salmon anaemia (ISA) outbreaks in Norway has been observed, mainly in the northern parts, which is also where farming of triploid fish has been licensed. The present study investigated the susceptibility of triploid Atlantic salmon to ISA both by field observations and experimental infections. Based on field observations, we found an increased susceptibility, with 9.4 increased odds to primary ISA outbreaks in triploid fish versus diploid fish at production-site level, and a tendency of increased odds (3.4) of ISA in triploid fish at individual cage level at sited with primary outbreaks. At some sites, ISA outbreaks were only diagnosed in cages with triploid fish and not in cages with diploid fish. Primary ISA outbreaks are the source for further spread of the disease, and it is noteworthy that in an experimental trial we found significantly more viral RNA in non-ISA-vaccinated triploid than in non-ISA-vaccinated diploid fish at the peak of the infection. Interestingly, the notable differences of susceptibility to ISA for non-ISA vaccinated diploid and triploid fish observed in field were not repeated experimentally. The possible increased risk of ISA should be considered when evaluating the costs and benefits of triploid salmon in farming. It is recommended to keep triploid and diploid fish in biosecure separated sites, or that triploid fish are not farmed at all.
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Affiliation(s)
- Arnfinn Aunsmo
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
- Laxar Fiskeldi, Reykjavik, Iceland
| | | | | | | | - Ane Sandtrø
- PHARMAQ, Skogmo Industriområde, Overhalla, Norway
| | | | - Stine Braaen
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Espen Rimstad
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Ås, Norway
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3
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Kossack C, Fuentes N, Maisey K. In silico prediction of B and T cell epitopes of infectious salmon anemia virus proteins and molecular modeling of T cell epitopes to salmon major histocompatibility complex (MHC) class I. FISH & SHELLFISH IMMUNOLOGY 2022; 128:335-347. [PMID: 35963560 DOI: 10.1016/j.fsi.2022.08.002] [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: 04/25/2022] [Revised: 07/31/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
Infectious salmon anemia (ISA) can be devastating in farmed Atlantic salmon (Salmo salar). The disease can evolve into epidemics if it is not contained and controlled. ISA epidemics were seen in Norway in the early 1990s and Chile in 2007-2009. Consequently, there is an urgent need to develop a vaccine to prevent or treat the infection. In this study, an immunoinformatic approach was employed to predict 32 lineal B-cell epitopes based on antigenicity and surface accessibility prediction for ISAV fusion (F), hemagglutinin-esterase (HE), and matrix (M) proteins. On the other hand, twelve conformational B-cell epitopes were also predicted. We further identified six antigenic cytotoxic T lymphocyte (CTL) epitopes and investigated the binding interactions with five salmon MHC-I proteins after docking the peptides to the binding groove of the MHC-I proteins. Our results showed that all the predicted epitopes could bind to salmon MHC-I with high negative ΔG values with medium to high binding affinities. Hence, the predicted epitopes have a high potential of being recognized by Atlantic salmon MHC-I to elicit a CD8+ T cell response in salmon. The predicted and analyzed B and T cell antigenic epitopes in this work might present an initial set of peptides for future vaccine development against ISAV. The ability to model and predict these interactions will ultimately lead to the ability to predict potential binding for MHCs and epitopes that were not studied previously. As current knowledge of salmon MHC specificity is limited, studying and modeling interactions in the peptide/MHC complex is a key to resolving unknown epitope specificity.
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Affiliation(s)
- C Kossack
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile
| | - N Fuentes
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile
| | - K Maisey
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile.
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4
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Weli SC, Bernhardt LV, Qviller L, Dale OB, Lillehaug A. Infectious Salmon Anemia Virus Shedding from Infected Atlantic Salmon ( Salmo salar L.)-Application of a Droplet Digital PCR Assay for Virus Quantification in Seawater. Viruses 2021; 13:v13091770. [PMID: 34578351 PMCID: PMC8471646 DOI: 10.3390/v13091770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/25/2021] [Accepted: 09/01/2021] [Indexed: 12/18/2022] Open
Abstract
Infectious salmon anemia virus (ISAV) infection is currently detected by fish sampling for PCR and immunohistochemistry analysis. As an alternative to sampling fish, we evaluated two different membrane filters in combination with four buffers for elution, concentration, and detection of ISAV in seawater, during a bath challenge of Atlantic salmon (Salmo salar L.) post-smolts with high and low concentrations of ISAV. Transmission of ISAV in the bath challenge was confirmed by a high mortality, clinical signs associated with ISA disease, and detection of ISAV RNA in organ tissues and seawater samples. The electronegatively charged filter, combined with lysis buffer, gave significantly higher ISAV RNA detection by droplet digital PCR from seawater (5.6 × 104 ISAV RNA copies/L; p < 0.001). Viral shedding in seawater was first detected at two days post-challenge and peaked on day 11 post-challenge, one day before mortalities started in fish challenged with high dose ISAV, demonstrating that a large viral shedding event occurs before death. These data provide important information for ISAV shedding that is relevant for the development of improved surveillance tools based on water samples, transmission models, and management of ISA.
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Flores-Kossack C, Montero R, Köllner B, Maisey K. Chilean aquaculture and the new challenges: Pathogens, immune response, vaccination and fish diversification. FISH & SHELLFISH IMMUNOLOGY 2020; 98:52-67. [PMID: 31899356 DOI: 10.1016/j.fsi.2019.12.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/29/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
In Chile, the salmon and trout farmed fishing industries have rapidly grown during the last years, becoming one of the most important economic sources for the country. However, infectious diseases caused by bacteria, virus, mycoses and parasites, result in losses of up to 700 million dollars per year for the Chilean aquaculture production with the consequent increase of antibiotic and antiparasitic usage. After 30 years of its first appearance, the main salmon health problem is still the salmonid rickettsial septicaemia (SRS), which together with other disease outbreaks, reveal that vaccines do not provide acceptable levels of long-lasting immune protection in the field. On the other hand, due to the large dependence of the industry on salmonids production, the Chilean government promoted the Aquaculture diversification program by 2009, which includes new species such as Merluccius australis, Cilus gilberti and Genypterus chilensis, however, specific research regarding the immune system and vaccine development are issues that still need to be addressed and must be considered as important as the farm production technologies for new fish species. Based on the experience acquired from the salmonid fish farming, should be mandatory an effort to study the immune system of the new species to develop knowledge for vaccination approaches, aiming to protect these aquaculture species before diseases outbreaks may occur. This review focuses on the current status of the Chilean aquaculture industry, the challenges related to emerging and re-emerging microbial pathogens on salmonid fish farming, and the resulting needs in the development of immune protection by rational designed vaccines. We also discussed about what we have learn from 25 years of salmonid researches and what can be applied to the new Chilean farmed species on immunology and vaccinology.
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Affiliation(s)
- C Flores-Kossack
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile
| | - R Montero
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - B Köllner
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - K Maisey
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile.
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6
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Madhun AS, Mæhle S, Wennevik V, Karlsbakk E. Prevalence and genotypes of infectious salmon anaemia virus (ISAV) in returning wild Atlantic salmon (Salmo salar L.) in northern Norway. JOURNAL OF FISH DISEASES 2019; 42:1217-1221. [PMID: 31192460 PMCID: PMC6851747 DOI: 10.1111/jfd.13021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/12/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Affiliation(s)
| | - Stig Mæhle
- Institute of Marine ResearchBergenNorway
| | | | - Egil Karlsbakk
- Institute of Marine ResearchBergenNorway
- Department of Biological SciencesUniversity of BergenBergenNorway
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7
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Dahle MK, Jørgensen JB. Antiviral defense in salmonids - Mission made possible? FISH & SHELLFISH IMMUNOLOGY 2019; 87:421-437. [PMID: 30708056 DOI: 10.1016/j.fsi.2019.01.043] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/24/2019] [Accepted: 01/27/2019] [Indexed: 06/09/2023]
Abstract
Viral diseases represent one of the major threats for salmonid aquaculture. Survival from viral infections are highly dependent on host innate antiviral immune defense, where interferons are of crucial importance. Neutralizing antibodies and T cell effector mechanisms mediate long-term antiviral protection. Despite an immune cell repertoire comparable to higher vertebrates, farmed fish often fail to mount optimal antiviral protection. In the quest to multiply and spread, viruses utilize a variety of strategies to evade or escape the host immune system. Understanding the specific interplay between viruses and host immunity at depth is crucial for developing successful vaccination and treatment strategies in mammals. However, this knowledge base is still limited for pathogenic fish viruses. Here, we have focused on five RNA viruses with major impact on salmonid aquaculture: Salmonid alphavirus, Infectious salmon anemia virus, Infectious pancreatic necrosis virus, Piscine orthoreovirus and Piscine myocarditis virus. This review explore the protective immune responses that salmonids mount to these viruses and the existing knowledge on how the viruses counteract and/or bypass the immune response, including their IFN antagonizing effects and their mechanisms to establish persisting infections.
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Affiliation(s)
- Maria K Dahle
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø, The Arctic University of Norway, Norway; Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
| | - Jorunn B Jørgensen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø, The Arctic University of Norway, Norway.
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8
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Arenas M, Araujo NM, Branco C, Castelhano N, Castro-Nallar E, Pérez-Losada M. Mutation and recombination in pathogen evolution: Relevance, methods and controversies. INFECTION GENETICS AND EVOLUTION 2017; 63:295-306. [PMID: 28951202 DOI: 10.1016/j.meegid.2017.09.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 02/06/2023]
Abstract
Mutation and recombination drive the evolution of most pathogens by generating the genetic variants upon which selection operates. Those variants can, for example, confer resistance to host immune systems and drug therapies or lead to epidemic outbreaks. Given their importance, diverse evolutionary studies have investigated the abundance and consequences of mutation and recombination in pathogen populations. However, some controversies persist regarding the contribution of each evolutionary force to the development of particular phenotypic observations (e.g., drug resistance). In this study, we revise the importance of mutation and recombination in the evolution of pathogens at both intra-host and inter-host levels. We also describe state-of-the-art analytical methodologies to detect and quantify these two evolutionary forces, including biases that are often ignored in evolutionary studies. Finally, we present some of our former studies involving pathogenic taxa where mutation and recombination played crucial roles in the recovery of pathogenic fitness, the generation of interspecific genetic diversity, or the design of centralized vaccines. This review also illustrates several common controversies and pitfalls in the analysis and in the evaluation and interpretation of mutation and recombination outcomes.
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Affiliation(s)
- Miguel Arenas
- Department of Biochemistry, Genetics and Immunology, University of Vigo, Vigo, Spain; Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Porto, Portugal; Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.
| | - Natalia M Araujo
- Laboratory of Molecular Virology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
| | - Catarina Branco
- Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Porto, Portugal; Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.
| | - Nadine Castelhano
- Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Porto, Portugal; Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.
| | - Eduardo Castro-Nallar
- Universidad Andrés Bello, Center for Bioinformatics and Integrative Biology, Facultad de Ciencias Biológicas, Santiago, Chile.
| | - Marcos Pérez-Losada
- Computational Biology Institute, Milken Institute School of Public Health, George Washington University, Ashburn, VA 20147, Washington, DC, United States; CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal.
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9
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Cárdenas C, Ojeda N, Labra A, Marshall SH. An updated proposal for classification of infectious salmon anemia virus strains. Arch Virol 2017; 162:2861-2867. [DOI: 10.1007/s00705-017-3440-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/31/2017] [Indexed: 10/19/2022]
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10
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Christiansen DH, McBeath AJA, Aamelfot M, Matejusova I, Fourrier M, White P, Petersen PE, Falk K. First field evidence of the evolution from a non-virulent HPR0 to a virulent HPR-deleted infectious salmon anaemia virus. J Gen Virol 2017; 98:595-606. [PMID: 28475029 DOI: 10.1099/jgv.0.000741] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The putatively non-virulent subtype of infectious salmon anaemia virus (ISAV), ISAV-HPR0, is proposed to act as a progenitor and reservoir for all virulent ISAVs and thus represent a potential risk factor for the emergence of infectious salmon anaemia (ISA) disease. Here, we provide the first evidence of genetic and functional evolution from an ISAV-HPR0 variant (FO/07/12) to a low-virulent ISAV virus (FO/121/14) in a Faroese Atlantic salmon marine farm. The FO/121/14 virus infection was not associated with specific clinical signs of ISA and was confined to a single net-pen, while various ISAV-HPR0 subtypes were found circulating in most epidemiologically linked marine and freshwater farms. Sequence analysis of all eight segments revealed that the FO/121/14 virus was identical, apart from a substitution in the fusion (F) gene (Q266L) and a deletion in the haemagglutinin-esterase (HE) gene, to the FO/07/12 variant from a freshwater farm, which supplied smolts exclusively to the FO/121/14-positive net-pen. An immersion challenge with the FO/121/14 virus induced a systemic infection in Atlantic salmon associated with a low mortality and mild clinical signs confirming its low pathogenicity. Our results demonstrate that mutations in the F protein and deletions in the highly polymorphic region (HPR) of the HE protein represent a minimum requirement for ISAV to gain virulence and to switch cell tropism from a localized epithelial infection to a systemic endotheliotropic infection. This documents that ISAV-HPR0 represents a reservoir and risk factor for the emergence of ISA disease.
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Affiliation(s)
- Debes H Christiansen
- Faroese Food and Veterinary Authority, National Reference Laboratory for Fish Diseases, Tórshavn, Faroe Islands
| | | | | | | | | | - Patricia White
- Marine Scotland Science, Marine Laboratory, Aberdeen, Scotland
| | - Petra E Petersen
- Faroese Food and Veterinary Authority, National Reference Laboratory for Fish Diseases, Tórshavn, Faroe Islands
| | - Knut Falk
- Norwegian Veterinary Institute, Oslo, Norway
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11
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Caruffo M, Maturana C, Kambalapally S, Larenas J, Tobar JA. Protective oral vaccination against infectious salmon anaemia virus in Salmo salar. FISH & SHELLFISH IMMUNOLOGY 2016; 54:54-9. [PMID: 26994669 DOI: 10.1016/j.fsi.2016.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 02/13/2016] [Accepted: 03/10/2016] [Indexed: 05/19/2023]
Abstract
Infectious salmon anemia (ISA) is a systemic disease caused by an orthomyxovirus, which has a significant economic impact on the production of Atlantic salmon (Salmo salar). Currently, there are several commercial ISA vaccines available, however, those products are applied through injection, causing stress in the fish and leaving them susceptible to infectious diseases due to the injection process and associated handling. In this study, we evaluated an oral vaccine against ISA containing a recombinant viral hemagglutinin-esterase and a fusion protein as antigens. Our findings indicated that oral vaccination is able to protect Atlantic salmon against challenge with a high-virulence Chilean isolate. The oral vaccination was also correlated with the induction of IgM-specific antibodies. On the other hand, the vaccine was unable to modulate expression of the antiviral related gene Mx, showing the importance of the humoral response to the disease survival. This study provides new insights into fish protection and immune response induced by an oral vaccine against ISA, but also promises future development of preventive solutions or validation of the current existing therapies.
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Affiliation(s)
- Mario Caruffo
- Virbac-Centrovet, Av. Salomón Sack 255, Cerrillos, Santiago, Chile; Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa, 11735, La Pintana, Santiago, Chile
| | - Carlos Maturana
- Virbac-Centrovet, Av. Salomón Sack 255, Cerrillos, Santiago, Chile
| | - Swetha Kambalapally
- Advanced Bionutrition Corp., 7155 Columbia Gateway Drive, Suite H. Columbia, MD, 21046, USA
| | - Julio Larenas
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa, 11735, La Pintana, Santiago, Chile
| | - Jaime A Tobar
- Virbac-Centrovet, Av. Salomón Sack 255, Cerrillos, Santiago, Chile.
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12
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Localised Infection of Atlantic Salmon Epithelial Cells by HPR0 Infectious Salmon Anaemia Virus. PLoS One 2016; 11:e0151723. [PMID: 26999815 PMCID: PMC4801213 DOI: 10.1371/journal.pone.0151723] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/03/2016] [Indexed: 12/13/2022] Open
Abstract
Infectious salmon anaemia (ISA) is an important, systemic viral disease of farmed Atlantic salmon, Salmo salar L. Endothelial cells are the main target cells for highly virulent HPR-deleted ISA virus (ISAV) types. Here we examine the pathogenesis of non-virulent ISAV HPR0 infections, presenting evidence of an epithelial tropism for this virus type, including actual infection and replication in the epithelial cells. Whereas all HPR0 RT-qPCR positive gills prepared for cryosection tested positive by immunohistochemistry (IHC) and immunofluorescent labelling, only 21% of HPR0 RT-qPCR positive formalin-fixed paraffin-embedded gills were IHC positive, suggesting different methodological sensitivities. Only specific epithelial cell staining was observed and no staining was observed in endothelial cells of positive gills. Furthermore, using an ISAV segment 7 RT-PCR assay, we demonstrated splicing of HPR0, suggesting initial activation of the replication machinery in the epithelial gill cells. Immunological responses were investigated by the expression of interferon-related genes (e.g. Mx and γIP) and by ELISA for presence of anti-ISAV antibodies on samples taken sequentially over several months during an episode of transient HPR0 infection. All fish revealed a variable, but increased expression of the immunological markers in comparison to normal healthy fish. Taken together, we conclude that HPR0 causes a localized epithelial infection of Atlantic salmon.
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Gustafson L, Remmenga M, Sandoval Del Valle O, Ibarra R, Antognoli M, Gallardo A, Rosenfeld C, Doddis J, Enriquez Sais R, Bell E, Lara Fica M. Area contact networks and the spatio-temporal spread of infectious salmon anemia virus (ISAV) in Chile. Prev Vet Med 2016; 125:135-46. [PMID: 26774449 DOI: 10.1016/j.prevetmed.2016.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/21/2015] [Accepted: 01/03/2016] [Indexed: 10/22/2022]
Abstract
Area management, the coordination of production and biosecurity practices across neighboring farms, is an important disease control strategy in aquaculture. Area management in aquaculture escalated in prominence in response to outbreaks of infectious salmon anemia (ISA) internationally. Successes in disease control have been attributed to the separation achieved through area-level synchronized stocking, fallowing, movement restrictions, and fomite or pest control. Area management, however, is costly; often demanding extra biosecurity, lengthy or inconveniently timed fallows, and localization of equipment, personnel, and services. Yet, this higher-order organizational structure has received limited epidemiologic attention. Chile's National Fisheries and Aquaculture Service instigated area management practices in response to the 2007 emergence of ISA virus (ISAV). Longitudinal data simultaneously collected allowed retrospective evaluation of the impact of component tenets on virus control. Spatiotemporal analyses identified hydrographic linkages, shared ports, and fish transfers from areas with recent occurrence of ISAV as the strongest predictors of virus spread between areas, though specifics varied by ISAV type (here categorized as HPR0 for the non-virulent genotypes, and HPRv otherwise). Hydrographic linkages were most predictive in the period before implementation of enhanced biosecurity and fallowing regulations, suggesting that viral load can impact spread dynamics. HPR0 arose late in the study period, so few HPRv events were available by which to explore the hypothesis of HPR0 as progenitor of outbreaks. However, spatiotemporal patterns in HPRv occurrence were predictive of subsequent patterns in HPR0 detection, suggesting a parallel, or dependent, means of spread. Better data precision, breadth and consistency, common challenges for retrospective studies, could improve model fit; and, for HPR0, specification of diagnostic test accuracy would improve interpretation.
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Affiliation(s)
- L Gustafson
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States.
| | - M Remmenga
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States
| | - O Sandoval Del Valle
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
| | - R Ibarra
- SalmonChile, Department of Fish Health, Instituto Tecnologico del Salmon, Av. Juan Soler Manfredini 41, OF 1802 Puerto Montt, Chile
| | - M Antognoli
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States
| | - A Gallardo
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
| | - C Rosenfeld
- Instituto de Medicina Preventiva Veterinaria Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - J Doddis
- Instituto de Medicina Preventiva Veterinaria Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - R Enriquez Sais
- Lab de Biotecnologia y Patologia Acuatica Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - E Bell
- Colorado Department of Public Health and Environment, 4300 Cherry Creek Drive South, Denver, CO 80246, United States
| | - M Lara Fica
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
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14
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Kibenge MJ, Iwamoto T, Wang Y, Morton A, Routledge R, Kibenge FS. Discovery of variant infectious salmon anaemia virus (ISAV) of European genotype in British Columbia, Canada. Virol J 2016; 13:3. [PMID: 26732772 PMCID: PMC4702313 DOI: 10.1186/s12985-015-0459-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/28/2015] [Indexed: 12/12/2022] Open
Abstract
Background Infectious salmon anaemia (ISA) virus (ISAV) belongs to the genus Isavirus, family Orthomyxoviridae. ISAV occurs in two basic genotypes, North American and European. The European genotype is more widespread and shows greater genetic variation and greater virulence variation than the North American genotype. To date, all of the ISAV isolates from the clinical disease, ISA, have had deletions in the highly polymorphic region (HPR) on ISAV segment 6 (ISAV-HPRΔ) relative to ISAV-HPR0, named numerically from ISAV-HPR1 to over ISAV-HPR30. ISA outbreaks have only been reported in farmed Atlantic salmon, although ISAV has been detected by RT-PCR in wild fish. It is recognized that asymptomatically ISAV-infected fish exist. There is no universally accepted ISAV RT-qPCR TaqMan® assay. Most diagnostic laboratories use the primer-probe set targeting a 104 bp-fragment on ISAV segment 8. Some laboratories and researchers have found a primer-probe set targeting ISAV segment 7 to be more sensitive. Other researchers have published different ISAV segment 8 primer-probe sets that are highly sensitive. Methods In this study, we tested 1,106 fish tissue samples collected from (i) market-bought farmed salmonids and (ii) wild salmon from throughout British Columbia (BC), Canada, for ISAV using real time RT-qPCR targeting segment 8 and/or conventional RT-PCR with segment 8 primers and segment 6 HPR primers, and by virus isolation attempts using Salmon head kidney (SHK-1 and ASK-2) cell line monolayers. The sequences from the conventional PCR products were compared by multiple alignment and phylogenetic analyses. Results Seventy-nine samples were “non-negative” with at least one of these tests in one or more replicates. The ISAV segment 6 HPR sequences from the PCR products matched ISAV variants, HPR5 on 29 samples, one sample had both HPR5 and HPR7b and one matched HPR0. All sequences were of European genotype. In addition, alignment of sequences of the conventional PCR product segment 8 showed they had a single nucleotide mutation in the region of the probe sequence and a 9-nucleotide overlap with the reverse primer sequence of the real time RT-qPCR assay. None of the classical ISAV segment 8 sequences in the GenBank have this mutation in the probe-binding site of the assay, suggesting the presence of a novel ISAV variant in BC. A phylogenetic tree of these sequences showed that some ISAV sequences diverted early from the classical European genotype sequences, while others have evolved separately. All virus isolation attempts on the samples were negative, and thus the samples were considered “negative” in terms of the threshold trigger set for Canadian federal regulatory action; i.e., successful virus isolation in cell culture. Conclusions This is the first published report of the detection of ISAV sequences in fish from British Columbia, Canada. The sequences detected, both of ISAV-HPRΔ and ISAV-HPR0 are of European genotype. These sequences are different from the classical ISAV segment 8 sequences, and this difference suggests the presence of a new ISAV variant of European genotype in BC. Our results further suggest that ISAV-HPRΔ strains can be present without clinical disease in farmed fish and without being detected by virus isolation using fish cell lines. Electronic supplementary material The online version of this article (doi:10.1186/s12985-015-0459-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Molly Jt Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, P.E.I., C1A 4P3, Canada.
| | - Tokinori Iwamoto
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, P.E.I., C1A 4P3, Canada. .,Current address: Diagnostic Services Unit, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, P.E.I., C1A 4P3, Canada.
| | - Yingwei Wang
- Department of Computer Science, University of Prince Edward Island, 550 University Ave., Charlottetown, P.E.I., C1A 4P3, Canada.
| | - Alexandra Morton
- Raincoast Research Society, Box 399, 390 1st Street, Sointula, BC, V0N 3E0, Canada.
| | - Richard Routledge
- Department of Statistics and Actuarial Science, Simon Fraser University, 8888 University Drive, Burnaby, B.C., V5A 1S6, Canada.
| | - Frederick Sb Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, P.E.I., C1A 4P3, Canada.
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15
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Development of a reverse genetic system for infectious salmon anemia virus: rescue of recombinant fluorescent virus by using salmon internal transcribed spacer region 1 as a novel promoter. Appl Environ Microbiol 2016; 81:1210-24. [PMID: 25480750 DOI: 10.1128/aem.03153-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Infectious salmon anemia (ISA) is a serious disease of marine-farmed Atlantic salmon (Salmo salar) caused by ISA virus (ISAV), belonging to the genus Isavirus, family Orthomyxoviridae. There is an urgent need to understand the virulence factors and pathogenic mechanisms of ISAV and to develop new vaccine approaches. Using a recombinant molecular biology approach, we report the development of a plasmid-based reverse genetic system for ISAV, which includes the use of a novel fish promoter, the Atlantic salmon internal transcribed spacer region 1 (ITS-1). Salmon cells cotransfected with pSS-URG-based vectors expressing the eight viral RNA segments and four cytomegalovirus (CMV)-based vectors that express the four proteins of the ISAV ribonucleoprotein complex allowed the generation of infectious recombinant ISAV (rISAV). We generated three recombinant viruses, wild-type rISAV(901_09) and rISAVr(S6-NotI-HPR) containing a NotI restriction site and rISAV(S6/EGFP-HPR) harboring the open reading frame of enhanced green fluorescent protein (EGFP), both within the highly polymorphic region (HPR) of segment 6. All rescued viruses showed replication activity and cytopathic effect in Atlantic salmon kidney-infected cells. The fluorescent recombinant viruses also showed a characteristic cytopathic effect in salmon cells, and the viruses replicated to a titer of 6.5105 PFU/ml,similar to that of the wild-type virus. This novel reverse genetics system offers a powerful tool to study the molecular biology of ISAV and to develop a new generation of ISAV vaccines to prevent and mitigate ISAV infection, which has had a profound effect on the salmon industry.
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16
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Kurath G, Winton JR, Dale OB, Purcell MK, Falk K, Busch RA. Atlantic salmon, Salmo salar L. are broadly susceptible to isolates representing the North American genogroups of infectious hematopoietic necrosis virus. JOURNAL OF FISH DISEASES 2016; 39:55-67. [PMID: 25381936 DOI: 10.1111/jfd.12323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 09/19/2014] [Accepted: 09/22/2014] [Indexed: 06/04/2023]
Abstract
Beginning in 1992, three epidemic waves of infectious hematopoietic necrosis, often with high mortality, occurred in farmed Atlantic salmon Salmo salar L. on the west coast of North America. We compared the virulence of eleven strains of infectious hematopoietic necrosis virus (IHNV), representing the U, M and L genogroups, in experimental challenges of juvenile Atlantic salmon in freshwater. All strains caused mortality and there was wide variation within genogroups: cumulative mortality for five U-group strains ranged from 20 to 100%, four M-group strains ranged 30-63% and two L-group strains varied from 41 to 81%. Thus, unlike Pacific salmonids, there was no apparent correlation of virulence in a particular host species with virus genogroup. The mortality patterns indicated two different phenotypes in terms of kinetics of disease progression and final per cent mortality, with nine strains having moderate virulence and two strains (from the U and L genogroups) having high virulence. These phenotypes were investigated by histopathology and immunohistochemistry to describe the variation in the course of IHNV disease in Atlantic salmon. The results from this study demonstrate that IHNV may become a major threat to farmed Atlantic salmon in other regions of the world where the virus has been, or may be, introduced.
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Affiliation(s)
- G Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - J R Winton
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - O B Dale
- Norwegian Veterinary Institute, Oslo, Norway
| | - M K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - K Falk
- Norwegian Veterinary Institute, Oslo, Norway
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17
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Kibenge F, Kibenge M. Orthomyxoviruses of Fish. AQUACULTURE VIROLOGY 2016. [PMCID: PMC7173593 DOI: 10.1016/b978-0-12-801573-5.00019-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The family Orthomyxoviridae is well known for containing influenza viruses with a segmented RNA genome that is prone to gene reassortment in mixed infections (known as antigenic shift) resulting in new virus subtypes that cause pandemics, and cumulative mutations (known as antigenic drift), resulting in new virus strains that cause epidemics. This family also contains infectious salmon anemia virus (ISAV) and tilapia lake virus (TiLV), which are a unique orthomyxoviruses that infect fish and is unable to replicate above room temperature (24°C). This chapter describes the comparative virology of members in the family Orthomyxoviridae in general, helping to understand the emergent teleost orthomyxoviruses, ISAV and TiLV. The most current information on virus–host interactions of the fish orthomyxoviruses, particularly ISAV, as they relate to variations in virus structure, virulence, persistence, host range and immunological aspects is presented in detail.
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18
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Fourrier M, Lester K, Markussen T, Falk K, Secombes CJ, McBeath A, Collet B. Dual Mutation Events in the Haemagglutinin-Esterase and Fusion Protein from an Infectious Salmon Anaemia Virus HPR0 Genotype Promote Viral Fusion and Activation by an Ubiquitous Host Protease. PLoS One 2015; 10:e0142020. [PMID: 26517828 PMCID: PMC4627773 DOI: 10.1371/journal.pone.0142020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/15/2015] [Indexed: 11/24/2022] Open
Abstract
In Infectious salmon anaemia virus (ISAV), deletions in the highly polymorphic region (HPR) in the near membrane domain of the haemagglutinin-esterase (HE) stalk, influence viral fusion. It is suspected that selected mutations in the associated Fusion (F) protein may also be important in regulating fusion activity. To better understand the underlying mechanisms involved in ISAV fusion, several mutated F proteins were generated from the Scottish Nevis and Norwegian SK779/06 HPR0. Co-transfection with constructs encoding HE and F were performed, fusion activity assessed by content mixing assay and the degree of proteolytic cleavage by western blot. Substitutions in Nevis F demonstrated that K276 was the most likely cleavage site in the protein. Furthermore, amino acid substitutions at three sites and two insertions, all slightly upstream of K276, increased fusion activity. Co-expression with HE harbouring a full-length HPR produced high fusion activities when trypsin and low pH were applied. In comparison, under normal culture conditions, groups containing a mutated HE with an HPR deletion were able to generate moderate fusion levels, while those with a full length HPR HE could not induce fusion. This suggested that HPR length may influence how the HE primes the F protein and promotes fusion activation by an ubiquitous host protease and/or facilitate subsequent post-cleavage refolding steps. Variations in fusion activity through accumulated mutations on surface glycoproteins have also been reported in other orthomyxoviruses and paramyxoviruses. This may in part contribute to the different virulence and tissue tropism reported for HPR0 and HPR deleted ISAV genotypes.
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Affiliation(s)
- Mickael Fourrier
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
- * E-mail:
| | - Katherine Lester
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
| | | | - Knut Falk
- Epidemiology, Norwegian Veterinary Institute, Oslo, Norway
| | | | - Alastair McBeath
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
| | - Bertrand Collet
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
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19
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McBeath A, Aamelfot M, Christiansen DH, Matejusova I, Markussen T, Kaldhusdal M, Dale OB, Weli SC, Falk K. Immersion challenge with low and highly virulent infectious salmon anaemia virus reveals different pathogenesis in Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2015; 38:3-15. [PMID: 24820820 DOI: 10.1111/jfd.12253] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 06/03/2023]
Abstract
The salmonid orthomyxovirus infectious salmon anaemia virus (ISAV) causes disease of varying severity in farmed Atlantic salmon, Salmo salar L. Field observations suggest that host factors, the environment and differences between ISAV strains attribute to the large variation in disease progression. Variation in host mortality and dissemination of ISAV isolates with high and low virulence (based on a previously published injection challenge) were investigated using immersion challenge. Virus dissemination was determined using real-time PCR and immunohistochemistry in several organs, including blood. Surprisingly, the low virulent virus (LVI) replicated and produced nucleoprotein at earlier time points post-infection compared to the virus of high virulence (HVI). This was particularly noticeable in the gills as indicated by different viral load profiles. However, the HVI reached a higher maximum viral load in all tested organs and full blood. This was associated with a higher mortality of 100% as compared to 20% in the LVI group by day 23 post-infection. Immersion challenge represented a more natural infection method and suggested that specific entry routes into the fish may be of key importance between ISAV strains. The results suggest that a difference in virulence is important for variations in virus dissemination and pathogenesis (disease development).
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Affiliation(s)
- A McBeath
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
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20
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Godoy MG, Suarez R, Lazo ES, Llegues KO, Kibenge MJT, Wang Y, Kibenge FSB. Genetic analysis and comparative virulence of infectious salmon anemia virus (ISAV) types HPR7a and HPR7b from recent field outbreaks in Chile. Virol J 2014; 11:204. [PMID: 25472899 PMCID: PMC4272776 DOI: 10.1186/s12985-014-0204-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/15/2014] [Indexed: 12/02/2022] Open
Abstract
Background Infectious salmon anemia (ISA) is a serious disease of marine farmed Atlantic salmon, Salmo salar L. caused by ISA virus (ISAV). ISAV genomic segments 5 and 6 encode surface glycoproteins hemagglutinin-esterase (HE) and F protein important for the pathogenicity of ISAV. In this study, we describe the genetic characteristics and relationship between ISAV-HPR7a and ISAV-HPR7b strains that caused the ISA outbreaks in Chile in 2013 and 2014, respectively, and the evolution of the ISAV clades since 2009 based on segment 5 and 6 sequences. Methods The study material included samples from six ISA cases in Chile. RNA was extracted from salmon tissues and ISAV isolated from cell culture; segments 5 and 6 were amplified by RT-PCR and compared by alignment with ISAV sequences from the GenBank database. Results ISAV-HPR7a and ISAV-HPR7b belong to the European Genotype I strains only found in Europe and Chile, and in both cases, show high similarity in segments 5 and 6 with identity between 95–96%. Our data confirm the hypothesis that the original virus was introduced to Chile in 1996. Compared to the 2007 ISAV-HPR7b isolate, the 2014 ISAV-HPR7b does not have an insertion in segment 5 and was associated with low mortality, which suggests that ISAV virulence was attenuated by the absence of the insertion in segment 5. In contrast, the highly virulent ISAV-HPR14 from April 2013 outbreak did not have the insertion in segment 5 either. Conclusion Variability in the ISAV virulence markers supports the quasispecies theory that multiple evolution forces are likely to shape ISAV genetic diversity. Our findings provide evidence of continuing evolution of ISAV in the Chilean aquaculture industry. Electronic supplementary material The online version of this article (doi:10.1186/s12985-014-0204-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marcos G Godoy
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile. .,Facultad de Medicina Veterinaria, Universidad San Sebastian, Lago Panguipulli 1390, Puerto Montt, Chile. .,ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile.
| | - Rudy Suarez
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile.
| | - Eduardo S Lazo
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile.
| | - Katerina O Llegues
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile.
| | - Molly J T Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada.
| | - Yingwei Wang
- Department of Computer Science and Information Technology, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada.
| | - Frederick S B Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada.
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21
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Abstract
Nearly half of all seafood consumed globally comes from aquaculture, a method of food production that has expanded rapidly in recent years. Increasing seafood consumption has been proposed as part of a strategy to combat the current non-communicable disease (NCD) pandemic, but public health, environmental, social, and production challenges related to certain types of aquaculture production must be addressed. Resolving these complicated human health and ecologic trade-offs requires systems thinking and collaboration across many fields; the One Health concept is an integrative approach that brings veterinary and human health experts together to combat zoonotic disease. We propose applying and expanding the One Health approach to facilitate collaboration among stakeholders focused on increasing consumption of seafood and expanding aquaculture production, using methods that minimize risks to public health, animal health, and ecology. This expanded application of One Health may also have relevance to other complex systems with similar trade-offs.
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Affiliation(s)
- Juan G. Gormaz
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Independencia 1027, Región Metropolitana Santiago, Chile
| | - Jillian P. Fry
- Johns Hopkins Center for a Livable Future, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205 USA
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205 USA
| | - Marcia Erazo
- School of Public Health, Faculty of Medicine, University of Chile, Independencia 1027, Región Metropolitana Santiago, Chile
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Región Metropolitana Santiago, Chile
| | - David C. Love
- Johns Hopkins Center for a Livable Future, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205 USA
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205 USA
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22
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Portnoy DS, Hollenbeck CM, Vidal RR, Gold JR. A comparison of neutral and immune genetic variation in Atlantic salmon, Salmo salar L. in Chilean aquaculture facilities. PLoS One 2014; 9:e99358. [PMID: 24918941 PMCID: PMC4053429 DOI: 10.1371/journal.pone.0099358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 05/14/2014] [Indexed: 12/17/2022] Open
Abstract
Genetic diversity was assessed in samples of cultured Atlantic salmon, Salmo salar L., obtained from facilities in Chile between 2005 and 2010, a period of time during which the infectious pathogens Infectious Salmon Anemia (ISA) virus, Caligus rogercresseyi (sea lice), and Piscirickettsia salmonis (salmon rickettsial syndrome) were common. Two panels of microsatellite markers were utilized: one with microsatellites with no known gene associations (neutral) and one featuring microsatellites linked to putative immune-related genes (immune-related). Allelic richness and gene diversity across samples were significantly greater in neutral loci as compared to immune-related loci. Both diversity measures were homogeneous among samples for immune-related loci and heterogeneous among samples for neutral loci. Immune-related loci were identified as F(ST) outliers in pairwise comparisons of samples at a 10-fold higher frequency than neutral loci. These results indicate that neutral and immune-related portions of the Atlantic salmon genome may have differed in response to the gauntlet of pathogens and that monitoring of specific, well characterized immune-related loci as well as neutral loci in cultured species could be useful when disease control and prevention is a goal.
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Affiliation(s)
- David S. Portnoy
- Department of Life Sciences, Texas A&M University, Corpus Christi, Texas, United States of America
- Marine Genomics Laboratory Harte Research Institute, Texas A&M University, Corpus Christi, Texas, United States of America
- * E-mail:
| | - Christopher M. Hollenbeck
- Marine Genomics Laboratory Harte Research Institute, Texas A&M University, Corpus Christi, Texas, United States of America
| | - R. Rodrigo Vidal
- Laboratory of Molecular Ecology, Genomics, and Evolutionary Studies, Department of Biology, University of Santiago de Chile, Santiago, Chile
| | - John R. Gold
- Department of Life Sciences, Texas A&M University, Corpus Christi, Texas, United States of America
- Marine Genomics Laboratory Harte Research Institute, Texas A&M University, Corpus Christi, Texas, United States of America
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23
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Raggi P, Lopez P, Diaz A, Carrasco D, Silva A, Velez A, Opazo R, Magne F, Navarrete PA. Debaryomyces hanseniiandRhodotorula mucilaginosacomprised the yeast core gut microbiota of wild and reared carnivorous salmonids, croaker and yellowtail. Environ Microbiol 2014; 16:2791-803. [DOI: 10.1111/1462-2920.12397] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/06/2014] [Accepted: 01/07/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Patricia Raggi
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
| | - Paulina Lopez
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
| | - Angélica Diaz
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
| | - Diana Carrasco
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
| | - Alfonso Silva
- Laboratorio de Cultivo de Peces; Universidad Católica del Norte; Coquimbo Chile
| | - Antonio Velez
- Centro de Desarrollo y Transferencia Tecnológica (CDTT); Fundación Chile; Tongoy Chile
| | - Rafael Opazo
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
| | - Fabien Magne
- CNRS UMR7212-Inserm U944-Université Paris Diderot; Conservatoire National des Arts et Métiers (CNAM); Paris France
- Institut de Recherche pour le Développement, delegation; Santiago Chile
| | - Paola A. Navarrete
- Laboratorio de Biotecnología; INTA; Universidad de Chile; Santiago Chile
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Vike S, Oelckers K, Duesund H, Erga SR, Gonzalez J, Hamre B, Frette O, Nylund A. Infectious salmon anemia (ISA) virus: infectivity in seawater under different physical conditions. JOURNAL OF AQUATIC ANIMAL HEALTH 2014; 26:33-42. [PMID: 24689956 DOI: 10.1080/08997659.2013.864720] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Infectious salmon anemia (ISA) virus (genus Isavirus, family Orthomyxoviridae), present in all major salmon producing countries, is the causative agent for a serious and commercially important disease affecting Atlantic Salmon Salmo salar. Nearly all ISA outbreaks occur in the marine production phase and knowledge about survival time for ISA virions in seawater is crucial for an adequate strategy to combat the disease. To acquire knowledge about this important factor, a study of ISA virus exposed to four different physical conditions was carried out. The virions' survival was tested in sterile seawater, sterile seawater with normal ultraviolet light radiation (UVR), natural seawater, and natural seawater with UVR. During the 72-h experiment both presence of ISA virus RNA and the infectivity of ISA virions were monitored. The result of this study showed that the infectivity of ISA virions is lost within 3 h of exposure to natural seawater or sterile seawater with UVR. However, it was possible to detect ISA virus RNA throughout the experimental period. This indicates that the effect of both UVR and biological activity of natural seawater limits the survival time of ISA virions under normal conditions. The survival time of ISA virions in sterile seawater was less than 24 h. Based on the available literature and the present study it is not very likely that passive horizontal transmission in seawater over long distances can occur. This is due to the following factors: (1) the effect of UVR and biological activity on ISA virions infectivity found in the present study, (2) the speed and dilution effect in seawater currents in salmon farming areas, (3) the temperature during the major outbreak periods, and (4) the need for an infective dose of ISA virions to reach naive Atlantic Salmon.
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Affiliation(s)
- Siri Vike
- a Cermaq , Dronning Eufemias gate 16 , Oslo , N-0102 , Norway
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25
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Fourrier M, Lester K, Thoen E, Mikalsen A, Evensen Ø, Falk K, Collet B, McBeath A. Deletions in the highly polymorphic region (HPR) of infectious salmon anaemia virus HPR0 haemagglutinin-esterase enhance viral fusion and influence the interaction with the fusion protein. J Gen Virol 2014; 95:1015-1024. [PMID: 24486627 DOI: 10.1099/vir.0.061648-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Since the discovery of a non-virulent infectious salmon anaemia virus (ISAV) HPR0 variant, many studies have speculated on the functional role of deletions within the highly polymorphic region (HPR) of genomic segment 6, which codes for the haemagglutinin-esterase (HE) protein. To address this issue, mutant HE proteins with deletions in their HPR were generated from the Scottish HPR0 template (NWM10) and fusion-inducing activity was measured using lipid (octadecyl rhodamine B) and content mixing assays (firefly luciferase). Segment six HPR was found to have a strong influence on ISAV fusion, and deletions in this near-membrane region predominantly increased the fusion-inducing ability of the resulting HE proteins. The position and length of the HPR deletions were not significant factors, suggesting that they may affect fusion non-specifically. In comparison, the amino acid composition of the associated fusion (F) protein was a more crucial criterion. Antibody co-patching and confocal fluorescence demonstrated that the HE and F proteins were highly co-localized, forming defined clusters on the cell surface post-transfection. The binding of erythrocyte ghosts on the attachment protein caused a reduction in the percentage of co-localization, suggesting that ISAV fusion might be triggered through physical separation of the F and HE proteins. In this process, HPR deletion appeared to modulate and reduce the strength of interaction between the two glycoproteins, causing more F protein to be released and activated. This work provides a first insight into the mechanism of virulence acquisition through HPR deletion, with fusion enhancement acting as a major contributing factor.
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Affiliation(s)
- Mickael Fourrier
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - Katherine Lester
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - Even Thoen
- Norwegian Veterinary Institute, Oslo, Norway
| | - Aase Mikalsen
- Norwegian School of Veterinary Science, Oslo, Norway
| | | | - Knut Falk
- Norwegian Veterinary Institute, Oslo, Norway
| | - Bertrand Collet
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - Alastair McBeath
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
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Cárdenas C, Carmona M, Gallardo A, Labra A, Marshall SH. Coexistence in field samples of two variants of the infectious salmon anemia virus: a putative shift to pathogenicity. PLoS One 2014; 9:e87832. [PMID: 24498206 PMCID: PMC3907575 DOI: 10.1371/journal.pone.0087832] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/30/2013] [Indexed: 12/31/2022] Open
Abstract
Genetic reassortment plays an important role in the evolution of several segmented RNA viruses and in the epidemiology of their associated diseases. In particular, orthomyxoviruses show rapid fluctuation in the proportion of viral variants coexisting in an infected individual, especially under strong selective pressure. This is particularly relevant in salmon production carried out under confined and stressful conditions where one of the most feared pathogenic agents is the Infectious Salmon Anemia Virus, an orthomyxovirus family member whose biological behavior is only recently beginning to be understood. Pathogenicity of the virus has been mainly associated with deletions of the HPR region in coding segment 6 and the presence or absence of a specific insertion in a key region in coding segment 5. In this study we report, for the first time in Chile, the coexistence of two variants in fully asymptomatic fish. Of five samples analyzed, two were identified as the non-pathogenic variant, HPR0, and two as the highly pathogenic HPR7b variant, though with no clinical signs detectable in the fish. Interestingly, one of the samples unequivocally carried both variants, again without any clinical signs. Considering that in none of the samples the typical insertion in coding segment 5 was detected, it is our impression that this may represent a shift from the non-pathogenic HPR0 variant towards the highly infective HPR7b variant. If this were the case, the transition may be triggered first by deleting the corresponding sequence of the HPR region of segment 6, followed by the putative insertion in segment 5 to generate a virulent strain.
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Affiliation(s)
- Constanza Cárdenas
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Fraunhofer Chile Research, Santiago, Chile
| | | | | | - Alvaro Labra
- Laboratorio de Patógenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Servicio Nacional de Pesca y Acuicultura, Valparaíso, Chile
| | - Sergio H. Marshall
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Laboratorio de Patógenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Facultad de Ciencias, campus Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Fraunhofer Chile Research, Santiago, Chile
- * E-mail:
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Abstract
Over the past decade, aquaculture has grown at an average annual growth rate of approximately 6 % worldwide despite many challenges. Viral diseases are one of the major challenges that are threatening a sustainable growth of finfish farming globally. Vaccination of farmed fish plays an important role in commercial fish farming to mitigate viral diseases. In this review, we summarized the major viral diseases that have caused serious economic losses, and emerging diseases that pose a potential threat to aquaculture. The current status of viral vaccines in farmed fish are discussed, particularly the different types of vaccines that were licensed in recent years and are now commercially available, and the routes of delivery of those vaccines including the merits and demerits of each of these delivery method. Furthermore, the article provides an overview of different experimental vaccines that have been reported in the literatures in recent years besides highlighting the future need for developing cost-effective, oral vaccines that can be easily applicable at farm level.
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Markussen T, Sindre H, Jonassen CM, Tengs T, Kristoffersen AB, Ramsell J, Numanovic S, Hjortaas MJ, Christiansen DH, Dale OB, Falk K. Ultra-deep pyrosequencing of partial surface protein genes from infectious Salmon Anaemia virus (ISAV) suggest novel mechanisms involved in transition to virulence. PLoS One 2013; 8:e81571. [PMID: 24303056 PMCID: PMC3841194 DOI: 10.1371/journal.pone.0081571] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 10/14/2013] [Indexed: 11/22/2022] Open
Abstract
Uncultivable HPR0 strains of infectious salmon anaemia viruses (ISAVs) infecting gills are non-virulent putative precursors of virulent ISAVs (vISAVs) causing systemic disease in farmed Atlantic salmon (Salmo salar). The transition to virulence involves two molecular events, a deletion in the highly polymorphic region (HPR) of the hemagglutinin-esterase (HE) gene and a Q266→L266 substitution or insertion next to the putative cleavage site (R267) in the fusion protein (F). We have performed ultra-deep pyrosequencing (UDPS) of these gene regions from healthy fish positive for HPR0 virus carrying full-length HPR sampled in a screening program, and a vISAV strain from an ISA outbreak at the same farming site three weeks later, and compared the mutant spectra. As the UDPS data shows the presence of both HE genotypes at both sampling times, and the outbreak strain was unlikely to be directly related to the HPR0 strain, this is the first report of a double infection with HPR0s and vISAVs. For F amplicon reads, mutation frequencies generating L266 codons in screening samples and Q266 codons in outbreak samples were not higher than at any random site. We suggest quasispecies heterogeneity as well as RNA structural properties are linked to transition to virulence. More specifically, a mechanism where selected single point mutations in the full-length HPR alter the RNA structure facilitating single- or sequential deletions in this region is proposed. The data provides stronger support for the deletion hypothesis, as opposed to recombination, as the responsible mechanism for generating the sequence deletions in HE.
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Affiliation(s)
- Turhan Markussen
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
- * E-mail:
| | - Hilde Sindre
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | | | - Torstein Tengs
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | | | - Jon Ramsell
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | - Sanela Numanovic
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | - Monika J. Hjortaas
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | - Debes H. Christiansen
- National Reference Laboratory for Fish Diseases, Food and Veterinary Authority, Torshavn, Faroe Islands
| | - Ole Bendik Dale
- Department of Laboratory Services, Norwegian Veterinary Institute, Oslo, Norway
| | - Knut Falk
- Department of Health Surveillance, Norwegian Veterinary Institute, Oslo, Norway
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Godoy MG, Kibenge MJT, Suarez R, Lazo E, Heisinger A, Aguinaga J, Bravo D, Mendoza J, Llegues KO, Avendaño-Herrera R, Vera C, Mardones F, Kibenge FSB. Infectious salmon anaemia virus (ISAV) in Chilean Atlantic salmon (Salmo salar) aquaculture: emergence of low pathogenic ISAV-HPR0 and re-emergence of virulent ISAV-HPR∆: HPR3 and HPR14. Virol J 2013; 10:344. [PMID: 24268071 PMCID: PMC4222741 DOI: 10.1186/1743-422x-10-344] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 11/18/2013] [Indexed: 11/10/2022] Open
Abstract
ABSTACT Infectious salmon anaemia (ISA) is a serious disease of marine-farmed Atlantic salmon (Salmo salar) caused by ISA virus (ISAV), which belongs to the genus Isavirus, family Orthomyxoviridae. ISA is caused by virulent ISAV strains with deletions in a highly polymorphic region (HPR) of the hemagglutinin-esterase (HE) protein (designated virulent ISAV-HPR∆). This study shows the historic dynamics of ISAV-HPR∆ and ISAV-HPR0 in Chile, the genetic relationship among ISAV-HPR0 reported worldwide and between ISAV-HPR0 and ISAV-HPR∆ in Chile, and reports the 2013 ISA outbreak in Chile. The first ISA outbreak in Chile occurred from mid-June 2007 to 2010 and involved the virulent ISAV-HPR7b, which was then replaced by a low pathogenic ISAV-HPR0 variant. We analyzed this variant in 66 laboratory-confirmed ISAV-HPR0 cases in Chile in comparison to virulent ISAV-HPR∆ that caused two new ISA outbreaks in April 2013. Multiple alignment and phylogenetic analysis of HE sequences from all ISAV-HPR0 viruses allowed us to identify three genomic clusters, which correlated with three residue patterns of ISAV-HPR0 (360PST362, 360PAN362 and 360PAT362) in HPR. The virus responsible for the 2013 ISAV-HPR∆ cases in Chile belonged to ISAV-HPR3 and ISAV-HPR14, and in phylogenetic analyses, both clustered with the ISAV-HPR0 found in Chile. The ISAV-HPR14 had the ISAV-HPR0 residue pattern 360PAT362, which is the only type of ISAV-HPR0 variant found in Chile. This suggested to us that the 2013 ISAV-HPR∆ re-emerged from ISAV-HPR0 that is enzootic in Chilean salmon aquaculture and were not new introductions of virulent ISAV-HPR∆ to Chile. The clinical presentations and diagnostic evidence of the 2013 ISA cases indicated a mixed infection of ISAV with the ectoparasite Caligus rogercresseyi and the bacterium Piscirickettsia salmonis, which underscores the need for active ISAV surveillance in areas where ISAV-HPR0 is enzootic, to ensure early detection and control of new ISA outbreaks, as it is considered a risk factor. This is the first report of ISA linked directly to the presence of ISAV-HPR0, and provides strong evidence supporting the contention that ISAV-HPR0 shows a strong relationship to virulent ISAV-HPR∆ viruses and the possibility that it could mutate to virulent ISAV-HPR∆.
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Affiliation(s)
- Marcos G Godoy
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 8, Puerto Montt, Chile
- Facultad de Ciencias, Universidad San Sebastián, Lago Panguipulli 1390, Puerto Montt, Chile
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Molly JT Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, P.E.I., C1A 4P3, Canada
| | - Rudy Suarez
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 8, Puerto Montt, Chile
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Eduardo Lazo
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | | | - Javier Aguinaga
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Diego Bravo
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Julio Mendoza
- Mainstream Chile S.A, Av. Diego Portales 2000, piso 10 y 11, Puerto Montt, Chile
| | - Katerina O Llegues
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 8, Puerto Montt, Chile
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Rubén 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), Víctor Lamas 1290, PO Box 160-C, Concepción, Chile
| | - Cristian Vera
- ETECMA, Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
| | - Fernando Mardones
- Center for Animal Disease Modeling and Surveillance (CADMS), Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
| | - Frederick SB Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, P.E.I., C1A 4P3, Canada
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Mardones FO, Jansen PA, Valdes-Donoso P, Jarpa M, Lyngstad TM, Jimenez D, Carpenter TE, Perez AM. Within-farm spread of infectious salmon anemia virus (ISAV) in Atlantic salmon Salmo salar farms in Chile. DISEASES OF AQUATIC ORGANISMS 2013; 106:7-16. [PMID: 24062548 DOI: 10.3354/dao02639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Spread of infectious salmon anemia virus (ISAV) at the cage level was quantified using a subset of data from 23 Atlantic salmon Salmo salar farms located in southern Chile. Data collected from official surveillance activities were systematically organized to obtain detailed information on infectious salmon anemia (ISA) outbreaks. Descriptive statistics for outbreak duration, proportion of infected fish, and time to secondary infection were calculated to quantify the magnitude of ISAV incursions. Linear and multiple failure time (MFT) regression models were used to determine factors associated with the cage-level reproduction number (Rc) and hazard rate (HR) for recurrent events, respectively. In addition, the Knox test was used to assess if cage-to-cage transmissions were clustered in space and time. Findings suggest that within farms, ISA outbreaks, on average, lasted 30 wk (median = 26 wk, 95% CI = 24 to 37 wk) and affected 57.3% (95% CI = 47.7 to 67.0%) of susceptible cages. The median time to secondarily diagnosed cages was 23 d. Occurrence of clinical ISAV outbreaks was significantly associated with increased Rc, whereas increased HR was significantly associated with clinical outbreaks and with a large number of fish. Spatio-temporal analysis failed to identify clustering of cage cases, suggesting that within-farm ISAV spread is independent of the spatial location of the cages. Results presented here will help to better understand ISAV transmission, to improve the design of surveillance programs in Chile and other regions in which salmon are intensively farmed, and to examine the economic impact of ISAV and related management strategies on various cost and demand shifting factors.
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Affiliation(s)
- F O Mardones
- Center for Animal Disease Modeling and Surveillance (CADMS), Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
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Kibenge MJT, Iwamoto T, Wang Y, Morton A, Godoy MG, Kibenge FSB. Whole-genome analysis of piscine reovirus (PRV) shows PRV represents a new genus in family Reoviridae and its genome segment S1 sequences group it into two separate sub-genotypes. Virol J 2013; 10:230. [PMID: 23844948 PMCID: PMC3711887 DOI: 10.1186/1743-422x-10-230] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/05/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Piscine reovirus (PRV) is a newly discovered fish reovirus of anadromous and marine fish ubiquitous among fish in Norwegian salmon farms, and likely the causative agent of heart and skeletal muscle inflammation (HSMI). HSMI is an increasingly economically significant disease in Atlantic salmon (Salmo salar) farms. The nucleotide sequence data available for PRV are limited, and there is no genetic information on this virus outside of Norway and none from wild fish. METHODS RT-PCR amplification and sequencing were used to obtain the complete viral genome of PRV (10 segments) from western Canada and Chile. The genetic diversity among the PRV strains and their relationship to Norwegian PRV isolates were determined by phylogenetic analyses and sequence identity comparisons. RESULTS PRV is distantly related to members of the genera Orthoreovirus and Aquareovirus and an unambiguous new genus within the family Reoviridae. The Canadian and Norwegian PRV strains are most divergent in the segment S1 and S4 encoded proteins. Phylogenetic analysis of PRV S1 sequences, for which the largest number of complete sequences from different "isolates" is available, grouped Norwegian PRV strains into a single genotype, Genotype I, with sub-genotypes, Ia and Ib. The Canadian PRV strains matched sub-genotype Ia and Chilean PRV strains matched sub-genotype Ib. CONCLUSIONS PRV should be considered as a member of a new genus within the family Reoviridae with two major Norwegian sub-genotypes. The Canadian PRV diverged from Norwegian sub-genotype Ia around 2007 ± 1, whereas the Chilean PRV diverged from Norwegian sub-genotype Ib around 2008 ± 1.
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Affiliation(s)
- Molly JT Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI C1A 4P3, Canada
| | - Tokinori Iwamoto
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI C1A 4P3, Canada
| | - Yingwei Wang
- Department of Computer Science and Information Technology, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI C1A 4P3, Canada
| | - Alexandra Morton
- Raincoast Research Society, Box 399, 390 1st Street, Sointula, BC V0N 3E0, Canada
| | - Marcos G Godoy
- Centro de Investigaciones Biológicas Aplicadas (CIBA), Diego de Almagro Norte 1013, No. 10, Puerto Montt, Chile
- Universidad San Sebastián. Facultad de Ciencias, Lago Panguipulli 1390, Puerto Montt, Chile
- ETECMA, Diego de Almagro Norte 1013 No. 10, Sector Cardonal, Puerto Montt, X Región, Chile
| | - Frederick SB Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI C1A 4P3, Canada
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Tello M, Saavedra JM, Spencer E. Analysis of the use of codon pairs in the HE gene of the ISA virus shows a correlation between bias in HPR codon-pair use and mortality rates caused by the virus. Virol J 2013; 10:180. [PMID: 23742749 PMCID: PMC3684539 DOI: 10.1186/1743-422x-10-180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/28/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Segment 6 of the ISA virus codes for hemoagglutinin-esterase (HE). This segment is highly variable, with more than 26 variants identified. The major variation is observed in what is called the high polymorphism region (HPR). The role of the different HPR zones in the viral cycle or evolution remains unknown. However viruses that present the HPR0 are avirulent, while viruses with important deletions in this region have been responsible for outbreaks with high mortality rates. In this work, using bioinformatic tools, we examined the influence of different HPRs on the adaptation of HE genes to the host translational machinery and the relationship to observed virulence. METHODS Translational efficiency of HE genes and their HPR were estimated analyzing codon-pair bias (CPB), adaptation to host codon use (codon adaptation index-CAI) and the adaptation to available tRNAs (tAI). These values were correlated with reported mortality for the respective ISA virus and the ΔG of RNA folding. tRNA abundance was inferred from tRNA gene numbers identified in the Salmo salar genome using tRNAScan-SE. Statistical correlation between data was performed using a non-parametric test. RESULTS We found that HPR0 contains zones with codon pairs of low frequency and low availability of tRNA with respect to salmon codon-pair usage, suggesting that HPR modifies HE translational efficiency. Although calculating tAI was impossible because one third of tRNAs (~60.000) were tRNA-ala, translational efficiency measured by CPB shows that as HPR size increases, the CPB value of the HE gene decreases (P = 2x10⁻⁷, ρ = -0.675, n = 63) and that these values correlate positively with the mortality rates caused by the virus (ρ = 0.829, P = 2x10⁻⁷, n = 11). The mortality associated with different virus isolates or their corresponding HPR sizes were not related with the ΔG of HPR RNA folding, suggesting that the secondary structure of HPR RNA does not modify virulence. CONCLUSIONS Our results suggest that HPR size affects the efficiency of gene translation, which modulates the virulence of the virus by a mechanism similar to that observed in production of live attenuated vaccines through deoptimization of codon-pair usage.
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Affiliation(s)
- Mario Tello
- Centro de Biotecnología Acuícola, Facultad de Química y Biología, Universidad de Santiago de Chile, Alameda 3363, Santiago, Chile.
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Cabello FC, Godfrey HP, Tomova A, Ivanova L, Dölz H, Millanao A, Buschmann AH. Antimicrobial use in aquaculture re-examined: its relevance to antimicrobial resistance and to animal and human health. Environ Microbiol 2013; 15:1917-42. [PMID: 23711078 DOI: 10.1111/1462-2920.12134] [Citation(s) in RCA: 396] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/10/2013] [Accepted: 02/14/2013] [Indexed: 12/18/2022]
Abstract
The worldwide growth of aquaculture has been accompanied by a rapid increase in therapeutic and prophylactic usage of antimicrobials including those important in human therapeutics. Approximately 80% of antimicrobials used in aquaculture enter the environment with their activity intact where they select for bacteria whose resistance arises from mutations or more importantly, from mobile genetic elements containing multiple resistance determinants transmissible to other bacteria. Such selection alters biodiversity in aquatic environments and the normal flora of fish and shellfish. The commonality of the mobilome (the total of all mobile genetic elements in a genome) between aquatic and terrestrial bacteria together with the presence of residual antimicrobials, biofilms, and high concentrations of bacteriophages where the aquatic environment may also be contaminated with pathogens of human and animal origin can stimulate exchange of genetic information between aquatic and terrestrial bacteria. Several recently found genetic elements and resistance determinants for quinolones, tetracyclines, and β-lactamases are shared between aquatic bacteria, fish pathogens, and human pathogens, and appear to have originated in aquatic bacteria. Excessive use of antimicrobials in aquaculture can thus potentially negatively impact animal and human health as well as the aquatic environment and should be better assessed and regulated.
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Affiliation(s)
- Felipe C Cabello
- Department of Microbiology and Immunology, New York Medical College, Valhalla, NY, 10595, USA.
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Hick P, Gore K, Whittington R. Molecular epidemiology of betanodavirus—Sequence analysis strategies and quasispecies influence outbreak source attribution. Virology 2013; 436:15-23. [DOI: 10.1016/j.virol.2012.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 09/28/2012] [Accepted: 10/05/2012] [Indexed: 11/24/2022]
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Lyngstad TM, Kristoffersen AB, Hjortaas MJ, Devold M, Aspehaug V, Larssen RB, Jansen PA. Low virulent infectious salmon anaemia virus (ISAV-HPR0) is prevalent and geographically structured in Norwegian salmon farming. DISEASES OF AQUATIC ORGANISMS 2012; 101:197-206. [PMID: 23324416 DOI: 10.3354/dao02520] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Infectious salmon anaemia (ISA) is a severe disease in farmed Atlantic salmon Salmo salar that has caused epidemic outbreaks in most salmon-producing countries worldwide. The disease is caused by virulent ISA virus (ISAV). Low virulent variants of the virus, characterised by a full-length sequence in the highly polymorphic region of segment 6 in the virus genome, have been reported with increasing frequencies. These variants of the virus, termed HPR0, have been proposed to be ancestors of virulent ISAV. We examined this idea through studies of the phylogeographic and environmental distribution of ISAV-HPR0, as well as phylogeographic associations between virulent ISAV and ISAV-HPR0. Samples from 232 fish groups were screened for ISAV. Real-time RT-PCR was used for detection of ISAV, and the ISAV haemagglutinin esterase (HE) gene was characterised for positive samples. A Mantel test was used to test phylogeographic associations between pairs of ISAV-HPR0 HE gene sequences. A rank test was used to test associations between HE gene sequences from virulent ISAV and ISAV-HPR0. ISAV-HPR0 was detected in fish groups both in freshwater and marine environments, and in juveniles, on-grown marine salmon and broodstock salmon. Genetic and geographic distances between pairs of ISAV-HPR0 HE gene sequences were positively correlated, suggesting that the population of ISAV-HPR0 is geographically structured. Finally, we found a spatial association between fish groups with virulent ISAV (n = 21) and fish groups with ISAV-HPR0 (n = 27), supporting the hypothesis that ISAV-HPR0 may undergo a transition to virulent ISAV.
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Affiliation(s)
- Trude M Lyngstad
- Norwegian Veterinary Institute, PO Box 750 Sentrum, 0106 Oslo, Norway.
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Kibenge FS, Godoy MG, Fast M, Workenhe S, Kibenge MJ. Countermeasures against viral diseases of farmed fish. Antiviral Res 2012; 95:257-81. [DOI: 10.1016/j.antiviral.2012.06.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/01/2012] [Accepted: 06/09/2012] [Indexed: 12/24/2022]
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Integrative molecular phylogeography in the context of infectious diseases on the human-animal interface. Parasitology 2012; 139:1939-51. [PMID: 22931895 DOI: 10.1017/s0031182012001102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The rate of new emerging infectious diseases entering the human population has increased over the past century, with pathogens originating from animals or from products of animal origin accounting for the vast majority. Primary risk factors for the emergence and spread of emerging zoonoses include expansion and intensification of animal agriculture and long-distance live animal transport, live animal markets, bushmeat consumption and habitat destruction. Developing effective control strategies is contingent upon the ability to test causative hypotheses of disease transmission within a statistical framework. Broadly speaking, molecular phylogeography offers a framework in which specific hypotheses regarding pathogen gene flow and dispersal within an ecological context can be compared. A number of different methods has been developed for this application. Here, our intent is firstly to discuss the application of a wide variety of statistically based methods (including Bayesian reconstruction, network parsimony analysis and regression) to specific viruses (influenza, salmon anaemia virus, foot and mouth disease and Rift Valley Fever) that have been associated with animal farming/movements; and secondly to place them in the larger framework of the threat of potential zoonotic events as well as the economic and biosecurity implications of pathogen outbreaks among our animal food sources.
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Plarre H, Nylund A, Karlsen M, Brevik Ø, Sæther PA, Vike S. Evolution of infectious salmon anaemia virus (ISA virus). Arch Virol 2012; 157:2309-26. [DOI: 10.1007/s00705-012-1438-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 06/29/2012] [Indexed: 12/31/2022]
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Sepúlveda D, Cárdenas C, Carmona M, Marshall SH. Novel strategy to evaluate infectious salmon anemia virus variants by high resolution melting. PLoS One 2012; 7:e37265. [PMID: 22719837 PMCID: PMC3373561 DOI: 10.1371/journal.pone.0037265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 04/18/2012] [Indexed: 12/29/2022] Open
Abstract
Genetic variability is a key problem in the prevention and therapy of RNA-based virus infections. Infectious Salmon Anemia virus (ISAv) is an RNA virus which aggressively attacks salmon producing farms worldwide and in particular in Chile. Just as with most of the Orthomyxovirus, ISAv displays high variability in its genome which is reflected by a wider infection potential, thus hampering management and prevention of the disease. Although a number of widely validated detection procedures exist, in this case there is a need of a more complex approach to the characterization of virus variability. We have adapted a procedure of High Resolution Melting (HRM) as a fine-tuning technique to fully differentiate viral variants detected in Chile and projected to other infective variants reported elsewhere. Out of the eight viral coding segments, the technique was adapted using natural Chilean variants for two of them, namely segments 5 and 6, recognized as virulence-associated factors. Our work demonstrates the versatility of the technique as well as its superior resolution capacity compared with standard techniques currently in use as key diagnostic tools.
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Affiliation(s)
- Dagoberto Sepúlveda
- Laboratorio de Patógenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
| | - Constanza Cárdenas
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Marisela Carmona
- Laboratorio de Patógenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
| | - Sergio H. Marshall
- Laboratorio de Patógenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
- Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- * E-mail:
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Cortez-San Martin M, Rivas-Aravena A, Guajardo S, Castillo MT, Jashes M, Sandino AM, Spencer E. Simultaneous detection of the IPN and ISA viruses in outbreaks of clinical disease and mortality in farmed Atlantic salmon, Salmo salar L., in Chile. JOURNAL OF FISH DISEASES 2012; 35:461-465. [PMID: 22524494 DOI: 10.1111/j.1365-2761.2012.01359.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- M Cortez-San Martin
- Laboratorio de Virología, Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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Carmona M, Sepúlveda D, Cárdenas C, Nilo L, Marshall SH. Denaturing gradient gel electrophoresis (DGGE) as a powerful novel alternative for differentiation of epizootic ISA virus variants. PLoS One 2012; 7:e37353. [PMID: 22624020 PMCID: PMC3356253 DOI: 10.1371/journal.pone.0037353] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 04/20/2012] [Indexed: 11/18/2022] Open
Abstract
Infectious Salmon Anemia is a devastating disease critically affecting world-wide salmon production. Chile has been particularly stricken by this disease which in all cases has been directly related with its causative agent, a novel orthomyxovirus which presents specific and distinctive infective features. Among these, two molecular markers have been directly associated with pathogenicity in two of the eight RNA sub genomic coding units of the virus: an insertion hot spot region present in viral segment 5 and a Highly Polymorphic Region (HPR) located in viral segment 6. Here we report the successful adaptation of a PCR-dependent denaturing gel electrophoresis technique (DGGE), which enables differentiation of selected reported HPR epizootic variants detected in Chile. At the same time, the technique allows us to distinguish one nucleotide differences in sequences associated with the intriguing, and still not well-understood, insertion events which tend to occur on RNA Segment 5. Thus, the versatility of the technique opens new opportunities for improved understanding of the complex biology of all ISA variants as well as possible applications to other highly variable pathogens.
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Affiliation(s)
- Marisela Carmona
- Laboratorio de Patologenos Acuícolas, Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Campus Curauma, Valparaíso, Chile
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Castro-Nallar E, Cortez-San Martín M, Mascayano C, Molina C, Crandall KA. Molecular phylodynamics and protein modeling of infectious salmon anemia virus (ISAV). BMC Evol Biol 2011; 11:349. [PMID: 22132866 PMCID: PMC3267707 DOI: 10.1186/1471-2148-11-349] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 12/02/2011] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND ISAV is a member of the Orthomyxoviridae family that affects salmonids with disastrous results. It was first detected in 1984 in Norway and from then on it has been reported in Canada, United States, Scotland and the Faroe Islands. Recently, an outbreak was recorded in Chile with negative consequences for the local fishing industry. However, few studies have examined available data to test hypotheses associated with the phylogeographic partitioning of the infecting viral population, the population dynamics, or the evolutionary rates and demographic history of ISAV. To explore these issues, we collected relevant sequences of genes coding for both surface proteins from Chile, Canada, and Norway. We addressed questions regarding their phylogenetic relationships, evolutionary rates, and demographic history using modern phylogenetic methods. RESULTS A recombination breakpoint was consistently detected in the Hemagglutinin-Esterase (he) gene at either side of the Highly Polymorphic Region (HPR), whereas no recombination breakpoints were detected in Fusion protein (f) gene. Evolutionary relationships of ISAV revealed the 2007 Chilean outbreak group as a monophyletic clade for f that has a sister relationship to the Norwegian isolates. Their tMRCA is consistent with epidemiological data and demographic history was successfully recovered showing a profound bottleneck with further population expansion. Finally, selection analyses detected ongoing diversifying selection in f and he codons associated with protease processing and the HPR region, respectively. CONCLUSIONS Our results are consistent with the Norwegian origin hypothesis for the Chilean outbreak clade. In particular, ISAV HPR0 genotype is not the ancestor of all ISAV strains, although SK779/06 (HPR0) shares a common ancestor with the Chilean outbreak clade. Our analyses suggest that ISAV shows hallmarks typical of RNA viruses that can be exploited in epidemiological and surveillance settings. In addition, we hypothesized that genetic diversity of the HPR region is governed by recombination, probably due to template switching and that novel fusion gene proteolytic sites confer a selective advantage for the isolates that carry them. Additionally, protein modeling allowed us to relate the results of phylogenetic studies with the predicted structures. This study demonstrates that phylogenetic methods are important tools to predict future outbreaks of ISAV and other salmon pathogens.
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Affiliation(s)
- Eduardo Castro-Nallar
- Department of Biology, 401 Widtsoe Building, Brigham Young University, Provo, UT 84602-5181, USA.
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Presence of a full-length highly polymorphic region (HPR) in the ISAV haemagglutinin-esterase does not affect the primary functions of receptor binding and esterase activity. Arch Virol 2011; 156:2285-9. [PMID: 21935625 DOI: 10.1007/s00705-011-1106-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/05/2011] [Indexed: 10/17/2022]
Abstract
The putatively avirulent infectious salmon anaemia virus (ISAV) HPR0 variant has key phenotypic differences to isolates from disease outbreaks in Atlantic salmon farms. It appears to not cause disease, potentially displays a different tissue tropism and has yet to be isolated in conventional ISAV-permissive cell lines. This study focussed on identifying the biological basis for the observed differences by examining the properties of the haemagglutinin-esterase (HE) proteins derived from NWM10 (HPR0), Nevis 390/98 (HPR7 pathogenic strain) and mutant combinations of the two. Using a transfection-based system and haemadsorption analysis in salmon cell lines, this study demonstrated for the first time that an HPR0 HE was fully functional in terms of receptor-binding and -destroying activity and also suggested that the presence of a full-length HPR alone did not appear to affect these functions.
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Peeler EJ, Taylor NGH. The application of epidemiology in aquatic animal health -opportunities and challenges. Vet Res 2011; 42:94. [PMID: 21834990 PMCID: PMC3182899 DOI: 10.1186/1297-9716-42-94] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 08/11/2011] [Indexed: 11/17/2022] Open
Abstract
Over recent years the growth in aquaculture, accompanied by the emergence of new and transboundary diseases, has stimulated epidemiological studies of aquatic animal diseases. Great potential exists for both observational and theoretical approaches to investigate the processes driving emergence but, to date, compared to terrestrial systems, relatively few studies exist in aquatic animals. Research using risk methods has assessed routes of introduction of aquatic animal pathogens to facilitate safe trade (e.g. import risk analyses) and support biosecurity. Epidemiological studies of risk factors for disease in aquaculture (most notably Atlantic salmon farming) have effectively supported control measures. Methods developed for terrestrial livestock diseases (e.g. risk-based surveillance) could improve the capacity of aquatic animal surveillance systems to detect disease incursions and emergence. The study of disease in wild populations presents many challenges and the judicious use of theoretical models offers some solutions. Models, parameterised from observational studies of host pathogen interactions, have been used to extrapolate estimates of impacts on the individual to the population level. These have proved effective in estimating the likely impact of parasite infections on wild salmonid populations in Switzerland and Canada (where the importance of farmed salmon as a reservoir of infection was investigated). A lack of data is often the key constraint in the application of new approaches to surveillance and modelling. The need for epidemiological approaches to protect aquatic animal health will inevitably increase in the face of the combined challenges of climate change, increasing anthropogenic pressures, limited water sources and the growth in aquaculture.
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Affiliation(s)
- Edmund J Peeler
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset, DT4 8UB, UK
| | - Nicholas GH Taylor
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset, DT4 8UB, UK
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Mutoloki S, Evensen Ø. Sequence similarities of the capsid gene of Chilean and European isolates of infectious pancreatic necrosis virus point towards a common origin. J Gen Virol 2011; 92:1721-1726. [DOI: 10.1099/vir.0.030270-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The Chilean salmonid industry was developed by importing breeding materials, a practice still in effect due to deficits in the national supply of roe. Importation of breeding materials is often associated with the transmission of pathogens. The objectives of this study were to compare the infectious pancreatic necrosis virus (IPNV) isolates from Chile to those of European origin and to determine the diversity of the Chilean IPNV. The VP2 genes of IPNV from Chilean fish (whose eggs originated from Scotland, Iceland and Norway) were compared to isolates from fish in Norway and Ireland. The results show that the isolates are identical (97–99 %) and cluster into one genogroup. Our findings support previous reports of association between the trade-in breeding materials and transmission of pathogens. Furthermore, our results demonstrate the genotypic diversity of Chilean IPNV isolates. These findings have important implications for IPNV disease diagnosis and control in Chile.
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Affiliation(s)
- Stephen Mutoloki
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, PO Box 8146 Dep., 0033 Oslo, Norway
| | - Øystein Evensen
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, PO Box 8146 Dep., 0033 Oslo, Norway
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Snow M. The contribution of molecular epidemiology to the understanding and control of viral diseases of salmonid aquaculture. Vet Res 2011; 42:56. [PMID: 21466673 PMCID: PMC3080810 DOI: 10.1186/1297-9716-42-56] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 12/01/2010] [Indexed: 11/26/2022] Open
Abstract
Molecular epidemiology is a science which utilizes molecular biology to define the distribution of disease in a population (descriptive epidemiology) and relies heavily on integration of traditional (or analytical) epidemiological approaches to identify the etiological determinants of this distribution. The study of viral pathogens of aquaculture has provided many exciting opportunities to apply such tools. This review considers the extent to which molecular epidemiological studies have contributed to better understanding and control of disease in aquaculture, drawing on examples of viral diseases of salmonid fish of commercial significance including viral haemorrhagic septicaemia virus (VHSV), salmonid alphavirus (SAV) and infectious salmon anaemia virus (ISAV). Significant outcomes of molecular epidemiological studies include: Improved taxonomic classification of viruses A better understanding of the natural distribution of viruses An improved understanding of the origins of viral pathogens in aquaculture An improved understanding of the risks of translocation of pathogens outwith their natural host range An increased ability to trace the source of new disease outbreaks Development of a basis for ensuring development of appropriate diagnostic tools An ability to classify isolates and thus target future research aimed at better understanding biological function While molecular epidemiological studies have no doubt already made a significant contribution in these areas, the advent of new technologies such as pyrosequencing heralds a quantum leap in the ability to generate descriptive molecular sequence data. The ability of molecular epidemiology to fulfil its potential to translate complex disease pathways into relevant fish health policy is thus unlikely to be limited by the generation of descriptive molecular markers. More likely, full realisation of the potential to better explain viral transmission pathways will be dependent on the ability to assimilate and analyse knowledge from a range of more traditional information sources. The development of methods to systematically record and share such epidemiologically important information thus represents a major challenge for fish health professionals in making the best future use of molecular data in supporting fish health policy and disease control.
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Affiliation(s)
- Michael Snow
- Marine Scotland Science, 375 Victoria Road, Aberdeen, AB11 9DB Scotland, UK.
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Birkbeck TH, Feist SW, Verner-Jeffreys DW. Francisella infections in fish and shellfish. JOURNAL OF FISH DISEASES 2011; 34:173-187. [PMID: 21306585 DOI: 10.1111/j.1365-2761.2010.01226.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A series of recent reports have implicated bacteria from the family Francisellaceae as the cause of disease in farmed and wild fish and shellfish species such as Atlantic cod, Gadus morhua L., tilapia, Oreochromis spp., Atlantic salmon, Salmo salar L., three-line grunt, Parapristipoma trilineatum (Thunberg), ornamental cichlid species, hybrid striped bass Morone chrysops x M. saxatilis and, recently, a shellfish species, the giant abalone, Haliotisgigantea Gmelin. The range of taxa affected will very probably rise as it is likely that there has been considerable under-reporting to date of these disease agents. In common with other Francisella species, their isolation and culture require specialized solid and liquid media containing cysteine and a source of iron. This likely restricted earlier efforts to identify them correctly as the cause of disease in aquatic animals. The most information to date relates to disease in cod, caused by F. noatunensis and tilapia, caused by F. noatunensis subsp. orientalis (also termed F. asiatica), both causing granulomatous inflammatory reactions. Mortalities in both species can be high and, as the disease can likely be transferred via live fish movements, they pose a significant threat to tilapia and cod aquaculture operations. Although the fish-pathogenic Francisella species are classified in the same genus as the human pathogens F. tularensis, causative agent of tularemia, and F. philomiragia, the risk to humans from the fish and shellfish pathogenic Francisella species is considered very low.
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Affiliation(s)
- T H Birkbeck
- University of London Marine Biological Station, Millport, Isle of Cumbrae, Scotland, UK
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Gomez-Casado E, Estepa A, Coll J. A comparative review on European-farmed finfish RNA viruses and their vaccines. Vaccine 2011; 29:2657-71. [DOI: 10.1016/j.vaccine.2011.01.097] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 12/09/2010] [Accepted: 01/30/2011] [Indexed: 11/29/2022]
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Aldrin M, Lyngstad TM, Kristoffersen AB, Storvik B, Borgan Ø, Jansen PA. Modelling the spread of infectious salmon anaemia among salmon farms based on seaway distances between farms and genetic relationships between infectious salmon anaemia virus isolates. J R Soc Interface 2011; 8:1346-56. [PMID: 21325314 DOI: 10.1098/rsif.2010.0737] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Infectious salmon anaemia (ISA) is an important infectious disease in Atlantic salmon farming causing recurrent epidemic outbreaks worldwide. The focus of this paper is on tracing the spread of ISA among Norwegian salmon farms. To trace transmission pathways for the ISA virus (ISAV), we use phylogenetic relationships between virus isolates in combination with space-time data on disease occurrences. The rate of ISA infection of salmon farms is modelled stochastically, where seaway distances between farms and genetic distances between ISAV isolates from infected farms play prominent roles. The model was fitted to data covering all cohorts of farmed salmon and the history of all farms with ISA between 2003 and summer 2009. Both seaway and genetic distances were significantly associated with the rate of ISA infection. The fitted model predicts that the risk of infection from a neighbourhood infectious farm decreases with increasing seaway distance between the two farms. Furthermore, for a given infected farm with a given ISAV genotype, the source of infection is significantly more likely to be ISAV of a small genetic distance than of moderate or large genetic distances. Nearly half of the farms with ISA in the investigated period are predicted to have been infected by an infectious farm in their neighbourhood, whereas the remaining half of the infected farms had unknown sources. For many of the neighbourhood infected farms, it was possible to point out one or a few infectious farms as the most probable sources of infection. This makes it possible to map probable infection pathways.
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Affiliation(s)
- M Aldrin
- Norwegian Computing Center, PO Box 114 Blindern N-0314 Oslo, Norway.
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