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Ford CE, Dunn CD, Leis EM, Thiel WA, Goldberg TL. Five Species of Wild Freshwater Sport Fish in Wisconsin, USA, Reveal Highly Diverse Viromes. Pathogens 2024; 13:150. [PMID: 38392888 PMCID: PMC10891596 DOI: 10.3390/pathogens13020150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Studies of marine fish have revealed distant relatives of viruses important to global fish and animal health, but few such studies exist for freshwater fish. To investigate whether freshwater fish also host such viruses, we characterized the viromes of five wild species of freshwater fish in Wisconsin, USA: bluegill (Lepomis macrochirus), brown trout (Salmo trutta), lake sturgeon (Acipenser fulvescens), northern pike (Esox lucius), and walleye (Sander vitreus). We analyzed 103 blood serum samples collected during a state-wide survey from 2016 to 2020 and used a metagenomic approach for virus detection to identify known and previously uncharacterized virus sequences. We then characterized viruses phylogenetically and quantified prevalence, richness, and relative abundance for each virus. Within these viromes, we identified 19 viruses from 11 viral families: Amnoonviridae, Circoviridae, Coronaviridae, Hepadnaviridae, Peribunyaviridae, Picobirnaviridae, Picornaviridae, Matonaviridae, Narnaviridae, Nudnaviridae, and Spinareoviridae, 17 of which were previously undescribed. Among these viruses was the first fish-associated coronavirus from the Gammacoronavirus genus, which was present in 11/15 (73%) of S. vitreus. These results demonstrate that, similar to marine fish, freshwater fish also harbor diverse relatives of viruses important to the health of fish and other animals, although it currently remains unknown what effect, if any, the viruses we identified may have on fish health.
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Affiliation(s)
- Charlotte E. Ford
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (C.E.F.); (C.D.D.)
| | - Christopher D. Dunn
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (C.E.F.); (C.D.D.)
| | - Eric M. Leis
- U.S. Fish and Wildlife Service, La Crosse Fish Health Center—Midwest Fisheries Center, Onalaska, WI 54650, USA;
| | - Whitney A. Thiel
- Robert P. Hanson Laboratories, University of Wisconsin-Madison, Madison, WI 53706, USA;
| | - Tony L. Goldberg
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (C.E.F.); (C.D.D.)
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2
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Romero JF, Gardner IA, Hammell L, Groman D, Whelan D, O'Brien N, Hawkins LJ, Burnley H, Thakur K. Descriptive epidemiology of variants of infectious salmon anaemia virus in four Atlantic salmon farms in Newfoundland and Labrador, Canada. JOURNAL OF FISH DISEASES 2022; 45:919-930. [PMID: 35397120 DOI: 10.1111/jfd.13617] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
An incursion of infectious salmon anaemia virus (ISAV) was detected in 2020 in southern Newfoundland, Canada. This resulted in an outbreak affecting four marine farms stocking Atlantic salmon (Salmo salar L.) vaccinated against ISAV. This study provides the first description of epidemiologic characteristics of an ISAV outbreak in 2020 and 2021, and detected ISAV variants at the population level. Fish kidneys were screened for ISAV by real-time RT-PCR and non-negative samples were submitted for genotyping and further diagnostic testing. Nine distinct ISAV variants were identified: five European and three North American (NA) HPRΔ ISAV, and one NA-HPR0 ISAV variant. A notable finding was the concurrent detection of both an HPR0 and an HPRΔ ISAV variant in one individual fish. In two farms, both European and NA variants were simultaneously detected, while in the other two farms either NA or European variants were identified, but not both together. Generally, mortality increases followed rises in ISAV prevalence and cycle threshold values on RT-PCR decreased with time. Epidemiologic descriptions of ISAV outbreaks in Atlantic Canada contributes to the understanding of local disease dynamics and identification of changes thereof. Such insights are essential for the strengthening of disease management plans.
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Affiliation(s)
- João F Romero
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
- Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Ian A Gardner
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
- Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Larry Hammell
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
- Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - David Groman
- Aquatic Diagnostic Services, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Daryl Whelan
- Department of Fisheries, Forestry and Agriculture, Aquatic Animal Health Division, St. John's, Newfoundland and Labrador, Canada
| | - Nicole O'Brien
- Department of Fisheries, Forestry and Agriculture, Aquatic Animal Health Division, St. John's, Newfoundland and Labrador, Canada
| | | | - Holly Burnley
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
- Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Krishna Thakur
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
- Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
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3
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Rimstad E, Markussen T. Infectious salmon anaemia virus-molecular biology and pathogenesis of the infection. J Appl Microbiol 2020; 129:85-97. [PMID: 31885186 DOI: 10.1111/jam.14567] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 11/29/2022]
Abstract
Aquaculture has a long history in many parts of the world, but it is still young at an industrial scale. Marine fish farming in open nets of a single fish species at high densities compared to their wild compatriots opens a plethora of possible infections. Infectious salmon anaemia (ISA) is an example of disease that surfaced after large-scale farming of Atlantic salmon (Salmo salar) appeared. Here, a review of the molecular biology of the ISA virus (ISAV) with emphasis on its pathogenicity is presented. The avirulent HPR0 variant of ISAV has resisted propagation in cell cultures, which has restricted the ability to perform in vivo experiments with this variant. The transition from avirulent HPR0 to virulent HPRΔ has not been methodically studied under controlled experimental conditions, and the triggers of the transition from avirulent to virulent forms have not been mapped. Genetic segment reassortment, recombination and mutations are important mechanisms in ISAV evolution, and for the development of virulence. In the 25 years since the ISAV was identified, large amounts of sequence data have been collected for epidemiologic and transmission studies, however, the lack of good experimental models for HPR0 make the risk evaluation of the presence of this avirulent, ubiquitous variant uncertain. This review summarizes the current knowledge related to molecular biology and pathogenicity of this important aquatic orthomyxovirus.
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Affiliation(s)
- E Rimstad
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - T Markussen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
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4
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Probiotic mediated colonization resistance against E.coli infection in experimentally challenged Caenorhabditis elegans. Microb Pathog 2019; 127:39-47. [DOI: 10.1016/j.micpath.2018.11.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/26/2018] [Accepted: 11/26/2018] [Indexed: 01/05/2023]
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Cárdenas C, Ojeda N, Labra Á, Marshall SH. Molecular features associated with the adaptive evolution of Infectious Salmon Anemia Virus (ISAV) in Chile. INFECTION GENETICS AND EVOLUTION 2018; 68:203-211. [PMID: 30592977 DOI: 10.1016/j.meegid.2018.12.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 12/12/2018] [Accepted: 12/24/2018] [Indexed: 02/05/2023]
Abstract
Infectious salmon anemia virus (ISAV) is an Orthomyxovirus challenging salmon production, with a particular impact in Chile. During 2007-2010 a devastating and of unexpected consequences epizootic event almost destroyed a blooming industry in the country. The event was caused by an aggressive variant with a distinctive deletion in Segment 6, one of the eight genomic segments of the virus. After the outburst, although the infective viral variant seemed to have disappeared, a non-infective variant, not previously reported, was discovered and is characterized by a complete, non-deleted coding segment 6, which has prevailed in the fish population until now. This variant, known as HPR0, appears to be the ancestor strain of ISAV from which novel infective variants are generated. Additional variations in segment 5 have also been associated with the virulence observed in the field, an analysis of the differences in these two protein coding segments has been performed. It appears to us that a combinatorial effect exists between the features displayed by segments 5 and 6 which modulate the intensity of viral outbursts. As a result, a theoretical integrative model is presented which explains the different degree of virulence observed in the field based only on molecular data, this could help estimating the intensity of damage a given variant might exert over a productive farm.
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Affiliation(s)
- Constanza Cárdenas
- Núcleo de Biotecnología Curauma Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
| | - Nicolás Ojeda
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
| | - Álvaro Labra
- Laboratorio de referencia ISAV - OIE- Sernapesca, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
| | - Sergio H Marshall
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile; Núcleo de Biotecnología Curauma Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile; Laboratorio de referencia ISAV - OIE- Sernapesca, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
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6
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Gallagher MD, Matejusova I, Nguyen L, Ruane NM, Falk K, Macqueen DJ. Nanopore sequencing for rapid diagnostics of salmonid RNA viruses. Sci Rep 2018; 8:16307. [PMID: 30397226 PMCID: PMC6218516 DOI: 10.1038/s41598-018-34464-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/19/2018] [Indexed: 12/16/2022] Open
Abstract
Analysis of pathogen genome variation is essential for informing disease management and control measures in farmed animals. For farmed fish, the standard approach is to use PCR and Sanger sequencing to study partial regions of pathogen genomes, with second and third-generation sequencing tools yet to be widely applied. Here we demonstrate rapid and accurate sequencing of two disease-causing viruses affecting global salmonid aquaculture, salmonid alphavirus (SAV) and infectious salmon anaemia virus (ISAV), using third-generation nanopore sequencing on the MinION platform (Oxford Nanopore Technologies). Our approach complements PCR from infected material with MinION sequencing to recover genomic information that matches near perfectly to Sanger-verified references. We use this method to present the first SAV subtype-6 genome, which branches as the sister to all other SAV lineages in a genome-wide phylogenetic reconstruction. MinION sequencing offers an effective strategy for fast, genome-wide analysis of fish viruses, with major potential applications for diagnostics and robust investigations into the origins and spread of disease outbreaks.
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Affiliation(s)
- Michael D Gallagher
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, EH25 9RG, United Kingdom
| | - Iveta Matejusova
- Marine Scotland Science, Marine Laboratory, Aberdeen, AB11 9DB, United Kingdom
| | - Lien Nguyen
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom
| | - Neil M Ruane
- Fish Health Unit, Marine Institute, Rinville Oranmore, Co, Galway, Ireland
| | - Knut Falk
- Norwegian Veterinary Institute, Ullevålsveien 68, 0454, Oslo, Norway
| | - Daniel J Macqueen
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom.
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, EH25 9RG, United Kingdom.
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7
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Gagné N, LeBlanc F. Overview of infectious salmon anaemia virus (ISAV) in Atlantic Canada and first report of an ISAV North American-HPR0 subtype. JOURNAL OF FISH DISEASES 2018; 41:421-430. [PMID: 28782809 DOI: 10.1111/jfd.12670] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 06/07/2023]
Abstract
The infectious salmon anaemia virus (ISAV) is an important viral disease of farmed Atlantic salmon that has caused considerable financial losses for salmon farmers around the world, including Atlantic Canada. It is listed as a notifiable disease by the World Organization for Animal Health, and to this day, culling of infected cages or farms remains the current practice in many countries to mitigate the spread of the virus. In Atlantic Canada, ISAV was first detected in 1996 and continues to be detected. While some outbreaks seemed to have arisen from isolated infections of unknown source, others were local clusters resulting from horizontal spread of infection. This study provides a description of the detected ISAV isolates in Atlantic Canada between 2012 and 2016, and explores the phylogenetic relatedness between these ISAV isolates. A key finding is the detection for the first time of a North American-HPR0 ISAV subtype, which was predicted to exist for many years. Through phylogenetic analysis, a scenario emerges with at least three separate incursions of ISAV in Atlantic Canada. An initial ISAV introduction follows a genotypic separation between North America and Europe which resulted in the NA and EU genotypes known today; this separation predates the salmon aquaculture industry. The second incursion of ISAV from Europe to North America led to a sublineage in Atlantic Canada consisting of EU-HPR∆ isolates detected in Nova Scotia and New Brunswick, and the predominant form of ISAV-HPR0 (EU). Finally, we observed what could be the third and most recent incursion of ISAV in Newfoundland, in the form of an isolate highly similar to ISAV EU-HPR0 isolates found in the Faroe Islands and the one isolate from Norway.
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Affiliation(s)
- N Gagné
- Fisheries and Oceans Canada, Gulf Fisheries Center, Moncton, NB, Canada
| | - F LeBlanc
- Fisheries and Oceans Canada, Gulf Fisheries Center, Moncton, NB, Canada
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8
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Lago M, Rodríguez JF, Bandín I, Dopazo CP. Aquabirnavirus polyploidy: a new strategy to modulate virulence? J Gen Virol 2016; 97:1168-1177. [PMID: 26902908 DOI: 10.1099/jgv.0.000434] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One of the main research issues regarding infectious pancreatic necrosis virus (IPNV) is its virulence mechanisms. The basis for understanding the molecular virulence determinants of this virus was established over the last decade when it was demonstrated that certain amino acid domains in the VP2 and VP2-NS inter-region determined the level of virulence of IPNV. However, certain variability was still inexplicable and therefore other factors may also be involved. To this end, it was demonstrated recently that infectious bursal disease virus (IBDV), a virus in a different genus of the same family as IPNV, can package more than two dsRNA segments, and that polyploidy may be associated with virulence. In the present report, we analysed the viral fractions obtained after gradient centrifugation to demonstrate that IPNV virions can also package more than two segments, thus indicating that polyploidy is a common birnavirus trait. The differential replication ex vivo and virulence in vivo additionally suggested that such a characteristic is involved in the modulation of virus infectivity. However, although the ex vivo results clearly demonstrated that the replication capacity was enhanced as the viral ploidy increased, the in vivo results could not strongly support a direct relationship between ploidy and virulence to the host, thus suggesting that other virulence determinants are also involved.
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Affiliation(s)
- M Lago
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain
| | - José F Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología/CSIC,Cantoblanco, 28049 Madrid,Spain
| | - I Bandín
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain
| | - C P Dopazo
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain
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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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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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11
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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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