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Solarte-Murillo L, Reyes H, Ojeda L, Cárcamo JG, Pontigo JP, Loncoman CA. Analyses and Insights into Genetic Reassortment and Natural Selection as Key Drivers of Piscine orthoreovirus Evolution. Viruses 2024; 16:556. [PMID: 38675898 PMCID: PMC11053957 DOI: 10.3390/v16040556] [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] [Received: 01/05/2024] [Revised: 03/05/2024] [Accepted: 03/08/2024] [Indexed: 04/28/2024] Open
Abstract
Piscine orthoreovirus (PRV) is a pathogen that causes heart and skeletal muscle inflammation in Salmo salar and has also been linked to circulatory disorders in other farmed salmonids, such as Oncorhynchus kisutch and Oncorhynchus mykiss. The virus has a segmented, double-stranded RNA genome, which makes it possible to undergo genetic reassortment and increase its genomic diversity through point mutations. In this study, genetic reassortment in PRV was assessed using the full genome sequences available in public databases. This study used full genome sequences that were concatenated and genome-wide reassortment events, and phylogenetic analyses were performed using the recombination/reassortment detection program version 5 (RDP5 V 5.5) software. Additionally, each segment was aligned codon by codon, and overall mean distance and selection was tested using the Molecular Evolutionary Genetics Analysis X software, version 10.2 (MEGA X version 10.2). The results showed that there were 17 significant reassortment events in 12 reassortant sequences, involving genome exchange between low and highly virulent genotypes. PRV sequences from different salmonid host species did not appear to limit the reassortment. This study found that PRV frequently undergoes reassortment events to increase the diversity of its segmented genome, leading to antigenic variation and increased virulence. This study also noted that to date, no reassortment events have been described between PRV-1 and PRV-3 genotypes. However, the number of complete genomic sequences within each genotype is uneven. This is important because PRV-3 induces cross-protection against PRV-1, making it a potential vaccine candidate.
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Affiliation(s)
- Laura Solarte-Murillo
- Laboratorio de Virología Molecular, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile;
| | - Humberto Reyes
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile;
| | - Loreto Ojeda
- Laboratorio de Bioquímica Farmacológica, Virología y Biotecnología, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile
- Interdisciplinary Center for Aquaculture Research, INCAR, Concepción 4030000, Chile
| | - Juan G. Cárcamo
- Laboratorio de Bioquímica Farmacológica, Virología y Biotecnología, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile
- Interdisciplinary Center for Aquaculture Research, INCAR, Concepción 4030000, Chile
| | - Juan Pablo Pontigo
- Laboratorio Institucional, Facultad de Ciencias de la Naturaleza, Escuela de Medicina Veterinaria, Universidad San Sebastián, Puerto Montt 5400000, Chile;
| | - Carlos A. Loncoman
- Laboratorio de Virología Molecular, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile;
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Tsoulia T, Sundaram AYM, Braaen S, Jørgensen JB, Rimstad E, Wessel Ø, Dahle MK. Transcriptomics of early responses to purified Piscine orthoreovirus-1 in Atlantic salmon ( Salmo salar L.) red blood cells compared to non-susceptible cell lines. Front Immunol 2024; 15:1359552. [PMID: 38420125 PMCID: PMC10899339 DOI: 10.3389/fimmu.2024.1359552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Piscine red blood cells (RBC) are nucleated and have been characterized as mediators of immune responses in addition to their role in gas exchange. Salmonid RBC are major target cells of Piscine orthoreovirus-1 (PRV-1), the etiological agent of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar). PRV-1 replicates in RBC ex vivo, but no viral amplification has been possible in available A. salmon cell lines. To compare RBC basal transcripts and transcriptional responses to PRV-1 in the early phase of infection with non-susceptible cells, we exposed A. salmon RBC, Atlantic salmon kidney cells (ASK) and Salmon head kidney cells (SHK-1) to PRV-1 for 24 h. The RNA-seq analysis of RBC supported their previous characterization as pluripotent cells, as they expressed a wide repertoire of genes encoding pattern recognition receptors (PRRs), cytokine receptors, and genes implicated in antiviral activities. The comparison of RBC to ASK and SHK-1 revealed immune cell features exclusively expressed in RBC, such as genes involved in chemotactic activity in response to inflammation. Differential expression analysis of RBC exposed to PRV-1 showed 46 significantly induced genes (≥ 2-fold upregulation) linked to the antiviral response pathway, including RNA-specific PRRs and interferon (IFN) response factors. In SHK-1, PRV induced a more potent or faster antiviral response (213 genes induced). ASK cells showed a differential response pattern (12 genes induced, 18 suppressed) less characterized by the dsRNA-induced antiviral pathway. Despite these differences, the RIG-I-like receptor 3 (RLR3) in the family of cytosolic dsRNA receptors was significantly induced in all PRV-1 exposed cells. IFN regulatory factor 1 (IRF1) was significantly induced in RBC only, in contrast to IRF3/IRF7 induced in SHK-1. Differences in IRF expression and activity may potentially affect viral propagation.
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Affiliation(s)
- Thomais Tsoulia
- Departments of Aquatic Animal Health and Analysis and Diagnostics, Norwegian Veterinary Institute, Ås, Norway
- Department of Biotechnology, Fisheries and Economy, UiT Arctic University of Norway, Tromsø, Norway
| | - Arvind Y. M. Sundaram
- Departments of Aquatic Animal Health and Analysis and Diagnostics, Norwegian Veterinary Institute, Ås, Norway
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Stine Braaen
- Department of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Jorunn B. Jørgensen
- Department of Biotechnology, Fisheries and Economy, UiT Arctic University of Norway, Tromsø, Norway
| | - Espen Rimstad
- Department of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Øystein Wessel
- Department of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Maria K. Dahle
- Departments of Aquatic Animal Health and Analysis and Diagnostics, Norwegian Veterinary Institute, Ås, Norway
- Department of Biotechnology, Fisheries and Economy, UiT Arctic University of Norway, Tromsø, Norway
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Wang X, Li Y, Dong S, Wang C, Wang Y, Zhang H. Transcriptomic analysis reveals impact of gE/gI/TK deletions on host response to PRV infection. Virol J 2023; 20:303. [PMID: 38115115 PMCID: PMC10731697 DOI: 10.1186/s12985-023-02265-y] [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] [Received: 08/17/2023] [Accepted: 12/09/2023] [Indexed: 12/21/2023] Open
Abstract
BACKGROUND Pseudorabies virus (PRV) causes substantial losses in the swine industry worldwide. Attenuated PRV strains with deletions of immunomodulatory genes glycoprotein E (gE), glycoprotein I (gI) and thymidine kinase (TK) are candidate vaccines. However, the effects of gE/gI/TK deletions on PRV-host interactions are not well understood. METHODS To characterize the impact of gE/gI/TK deletions on host cells, we analyzed and compared the transcriptomes of PK15 cells infected with wild-type PRV (SD2017), PRV with gE/gI/TK deletions (SD2017gE/gI/TK) using RNA-sequencing. RESULTS The attenuated SD2017gE/gI/TK strain showed increased expression of inflammatory cytokines and pathways related to immunity compared to wild-type PRV. Cell cycle regulation and metabolic pathways were also perturbed. CONCLUSIONS Deletion of immunomodulatory genes altered PRV interactions with host cells and immune responses. This study provides insights into PRV vaccine design.
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Affiliation(s)
- Xiaoli Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian, China
| | - Yingguang Li
- Shandong Collaborative Innovation Center for Development of Veterinary Pharmaceuticals, College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Shaoming Dong
- Shandong Collaborative Innovation Center for Development of Veterinary Pharmaceuticals, College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Cong Wang
- China animal husbandry industry Co., Ltd, Beijing, China
| | - Yongming Wang
- Shandong Huahong Biological Engineering Co., Ltd, Binzhou, China
| | - Hongliang Zhang
- Shandong Collaborative Innovation Center for Development of Veterinary Pharmaceuticals, College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China.
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4
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Polinski MP, Vendramin N, Cuenca A, Garver KA. Piscine orthoreovirus: Biology and distribution in farmed and wild fish. JOURNAL OF FISH DISEASES 2020; 43:1331-1352. [PMID: 32935367 DOI: 10.1111/jfd.13228] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
Piscine orthoreovirus (PRV) is a common and widely distributed virus of salmonids. Since its discovery in 2010, the virus has been detected in wild and farmed stocks from North America, South America, Europe and East Asia in both fresh and salt water environments. Phylogenetic analysis suggests three distinct genogroups of PRV with generally discrete host tropisms and/or regional patterns. PRV-1 is found mainly in Atlantic (Salmo salar), Chinook (Oncorhynchus tshawytscha) and Coho (Oncorhynchus kisutch) Salmon of Europe and the Americas; PRV-2 has only been detected in Coho Salmon of Japan; and PRV-3 has been reported primarily in Rainbow Trout (Oncorhynchus mykiss) in Europe. All three genotypes can establish high-load systemic infections by targeting red blood cells for principal replication. Each genotype has also demonstrated potential to cause circulatory disease. At the same time, high-load PRV infections occur in non-diseased salmon and trout, indicating a complexity for defining PRV's role in disease aetiology. Here, we summarize the current body of knowledge regarding PRV following 10 years of study.
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Affiliation(s)
- Mark P Polinski
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - Niccoló Vendramin
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Argelia Cuenca
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Kyle A Garver
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
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5
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Bjørgen H, Kumar S, Gunnes G, Press CM, Rimstad E, Koppang EO. Immunopathological characterization of red focal changes in Atlantic salmon (Salmo salar) white muscle. Vet Immunol Immunopathol 2020; 222:110035. [PMID: 32200172 DOI: 10.1016/j.vetimm.2020.110035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/26/2020] [Accepted: 03/06/2020] [Indexed: 11/18/2022]
Abstract
Farmed Atlantic salmon (Salmo salar) are prone to various conditions affecting the quality of the fillet. A well-known but so far poorly understood condition is the focal red changes in muscle, often referred to as haemorrhages. Such changes are characterized by muscle necrosis, haemorrhages and acute inflammation. They can progress into focal melanised changes, a chronic inflammatory condition with melanin-producing leukocytes. The initial cause of intramuscular haemorrhages is unknown. In this study, we aimed to reveal some of their key immunological features. Samples of red focal changes were investigated by immunohistochemistry (IHC), in situ hybridization (ISH) and RT-qPCR for various immune markers. The results were compared with samples of melanised changes and control muscle, subjected to the same analyses. In all red changes, infiltrates with mononuclear cells were detected, consisting mostly of MHC class I/II+ cells, but also of CD3+ and CD8+ cells. ISH studies on IgM showed few to moderate amounts of B-cells in red focal changes. Trends in the RT-qPCR showed upregulation of genes related to innate immunity in the red changes, whereas genes related to adaptive immunity were upregulated in the melanised changes. An important result was the significant downregulation of the anti-inflammatory cytokine IL10 in all red changes. Our findings indicate that we can rule out an auto invasive nature of the changes. The downregulation of IL10 at an early phase is a trait for the condition.
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Affiliation(s)
- Håvard Bjørgen
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Subramani Kumar
- Centre for Biotechnology, Anna University, Chennai, 600 025, India.
| | - Gjermund Gunnes
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Charles McL Press
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Erling Olaf Koppang
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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6
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Dissemination of Piscine orthoreovirus-1 (PRV-1) in Atlantic Salmon ( Salmo salar) during the Early and Regenerating Phases of Infection. Pathogens 2020; 9:pathogens9020143. [PMID: 32093243 PMCID: PMC7169402 DOI: 10.3390/pathogens9020143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/12/2022] Open
Abstract
Piscine orthoreovirus-1 (PRV-1) can cause heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar), but the line of events from infection, pathologic change, and regeneration has not been thoroughly described. In this study, the cellular localization and variation of PRV-1 RNA and protein levels were analyzed at different times post-exposure in experimentally infected Atlantic salmon. Immunohistochemistry, flow cytometry, and Western blot were used for assessment of the presence of the PRV-1 σ1 protein, while RT-qPCR and in situ hybridization were performed for viral RNA. Histopathologic evaluation demonstrated that PRV-1 infection induced heart lesions typical of HSMI, such as severe epicarditis and myocarditis with degeneration of cardiomyocytes, necrosis, and diffuse cellular infiltration. PRV-1 infection of erythrocytes and the peak viral plasma level preceded virus presence in cardiomyocytes and hepatocytes. Arginase-2-positive, macrophage-like cells observed in the heart indicated possible polarization to M2 macrophages and the onset of regenerative processes, which may contribute to the recovery from HSMI. The virus was cleared from regenerating heart tissue and from hepatocytes, but persisted in erythrocytes.
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7
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Teige LH, Kumar S, Johansen GM, Wessel Ø, Vendramin N, Lund M, Rimstad E, Boysen P, Dahle MK. Detection of Salmonid IgM Specific to the Piscine Orthoreovirus Outer Capsid Spike Protein Sigma 1 Using Lipid-Modified Antigens in a Bead-Based Antibody Detection Assay. Front Immunol 2019; 10:2119. [PMID: 31552049 PMCID: PMC6743345 DOI: 10.3389/fimmu.2019.02119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 08/22/2019] [Indexed: 11/13/2022] Open
Abstract
Bead-based multiplex immunoassays are promising tools for determination of the specific humoral immune response. In this study, we developed a multiplexed bead-based immunoassay for the detection of Atlantic salmon (Salmo salar) antibodies against Piscine orthoreovirus (PRV). Three different genotypes of PRV (PRV-1, PRV-2, and PRV-3) cause disease in farmed salmonids. The PRV outer capsid spike protein σ1 is predicted to be a host receptor binding protein and a target for neutralizing and protective antibodies. While recombinant σ1 performed poorly as an antigen to detect specific antibodies, N-terminal lipid modification of recombinant PRV-1 σ1 enabled sensitive detection of specific IgM in the bead-based assay. The specificity of anti-PRV-1 σ1 antibodies was confirmed by western blotting and pre-adsorption of plasma. Binding of non-specific IgM to beads coated with control antigens also increased after PRV infection, indicating a release of polyreactive antibodies. This non-specific binding was reduced by heat treatment of plasma. The same immunoassay also detected anti-PRV-3 σ1 antibodies from infected rainbow trout. In summary, a refined bead based immunoassay created by N-terminal lipid-modification of the PRV-1 σ1 antigen allowed sensitive detection of anti-PRV-1 and anti-PRV-3 antibodies from salmonids.
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Affiliation(s)
- Lena Hammerlund Teige
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Subramani Kumar
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.,Stem Cell and Cancer Biology Lab, Centre for Biotechnology, Anna University, Chennai, India
| | - Grethe M Johansen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Niccolò Vendramin
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Morten Lund
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway.,PatoGen, Alesund, Norway
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Preben Boysen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Maria K Dahle
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
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8
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Vendramin N, Cuenca A, Sørensen J, Alencar ALF, Christiansen DH, Jacobsen JA, Axen C, Lieffrig F, Ruane NM, Martin P, Sheehan T, Iburg TM, Rimstad E, Olesen NJ. Presence and genetic variability of Piscine orthoreovirus genotype 1 (PRV-1) in wild salmonids in Northern Europe and North Atlantic Ocean. JOURNAL OF FISH DISEASES 2019; 42:1107-1118. [PMID: 31140193 DOI: 10.1111/jfd.13025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/11/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
Piscine orthoreovirus genotype 1 (PRV-1) is widespread in farmed Atlantic salmon (Salmo salar L.) populations in northern Europe, Canada and Chile. PRV-1 occurs in wild fish in Norway and Canada; however, little information of its geographical distribution in wild populations is currently available, and the effect of PRV-1 infection in wild populations is currently unknown. In this study, we present the findings of a survey conducted on 1,130 wild salmonids sampled in Denmark, Sweden, Ireland, Faroe Islands, France, Belgium and Greenland between 2008 and 2017. PRV-1 is reported for the first time in wild salmonids in Denmark, Sweden, Faroe Island and Ireland. The annual PRV-1 prevalence ranged from 0% in France, Belgium and Greenland to 43% in Faroe Islands. In total, 66 samples tested positive for PRV-1, including Atlantic salmon broodfish returning to spawn and Atlantic salmon collected at the feeding ground north of Faroe Islands. The phylogenetic analysis of S1 sequences of the PRV-1 isolates obtained in this survey did not show systematic geographical distribution. This study sheds light on the spread and genetic diversity of the virus identified in populations of free-living fish and provides rationale for screening wild broodfish used in restocking programmes.
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Affiliation(s)
- Niccoló Vendramin
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Argelia Cuenca
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Juliane Sørensen
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Anna L F Alencar
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Debes H Christiansen
- National Reference Laboratory for fish diseases, Faroese Food and Veterinary Authority (FFVA), Torshavn, Faroe Islands
| | - Jan A Jacobsen
- Havstovan Faroe Marine Research Institute (FAMRI), Torshavn, Faroe Islands
| | - Charlotte Axen
- Swedish National Veterinary Institute (SVA), Uppsala, Sweden
| | | | - Neil M Ruane
- Fish Health Unit, Marine Institute, Galway, Ireland
| | | | - Timothy Sheehan
- Northeast Fisheries Science Center, National Marine Fisheries Service, Woods Hole, Massachusetts
| | - Tine M Iburg
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | | | - Niels J Olesen
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
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9
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Evolution of the Piscine orthoreovirus Genome Linked to Emergence of Heart and Skeletal Muscle Inflammation in Farmed Atlantic Salmon ( Salmo salar). Viruses 2019; 11:v11050465. [PMID: 31121920 PMCID: PMC6563308 DOI: 10.3390/v11050465] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 01/09/2023] Open
Abstract
Heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar) was first diagnosed in Norway in 1999. The disease is caused by Piscine orthoreovirus-1 (PRV-1). The virus is prevalent in farmed Atlantic salmon, but not always associated with disease. Phylogeny and sequence analyses of 31 PRV-1 genomes collected over a 30-year period from fish with or without HSMI, grouped the viral sequences into two main monophylogenetic clusters, one associated with HSMI and the other with low virulent PRV-1 isolates. A PRV-1 strain from Norway sampled in 1988, a decade before the emergence of HSMI, grouped with the low virulent HSMI cluster. The two distinct monophylogenetic clusters were particularly evident for segments S1 and M2. Only a limited number of amino acids were unique to the association with HSMI, and they all located to S1 and M2 encoded proteins. The observed co-evolution of the S1-M2 pair coincided in time with the emergence of HSMI in Norway, and may have evolved through accumulation of mutations and/or segment reassortment. Sequences of S1-M2 suggest selection of the HSMI associated pair, and that this segment pair has remained almost unchanged in Norwegian salmon aquaculture since 1997. PRV-1 strains from the North American Pacific Coast and Faroe Islands have not undergone this evolution, and are more closely related to the PRV-1 precursor strains not associated with clinical HSMI.
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10
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Xu C, Wang J, Yang J, Lei C, Hu J, Sun X. NSP2 forms viroplasms during Dendrolimus punctatus cypovirus infection. Virology 2019; 533:68-76. [PMID: 31125854 DOI: 10.1016/j.virol.2019.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 10/26/2022]
Abstract
Reoviruses are thought to replicate and assemble in special cytoplasmic structures called 'viroplasms'. However, little is known about the viroplasms of the insect reoviruses, the cypoviruses. To investigate the viroplasm of Dendrolimus punctatus cypovirus (DpCPV), all proteins encoded by the 10 genomic segments of DpCPV were expressed in Sf9 cells using the Bac-to-Bac system. The viral nonstructural protein NSP2 formed viroplasm-like dots which showed close apposition with the endoplasmic reticulum and were surrounded by intracellular membranes during transfection. Colocalization and coimmunoprecipitation assays showed that NSP2 interacts with 4 of 6 structural proteins and another 2 nonstructural proteins, while NSP1 only colocalized with VP4, and NSP3 did not colocalize with any structural protein. Immunoelectron microscopy revealed that NSP2 were nearby the endoplasmic reticulum and mitochondria, and viral particles were present in the electron-dense inclusions formed by NSP2. We proposed that NSP2 is responsible for forming the viroplasms structures of DpCPV.
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Affiliation(s)
- Congrui Xu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jia Wang
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian Yang
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chengfeng Lei
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Jia Hu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Xiulian Sun
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China.
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11
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Wessel Ø, Krasnov A, Timmerhaus G, Rimstad E, Dahle MK. Antiviral Responses and Biological Concequences of Piscine orthoreovirus Infection in Salmonid Erythrocytes. Front Immunol 2019; 9:3182. [PMID: 30700987 PMCID: PMC6343427 DOI: 10.3389/fimmu.2018.03182] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 12/27/2018] [Indexed: 11/13/2022] Open
Abstract
Salmonid red blood cells are the main target cells for Piscine orthoreovirus (PRV). Three genotypes of PRV (PRV-1,2,3) infect Atlantic salmon (Salmo salar), Chinook salmon (Onchorhynchus tshawytscha), Coho salmon (Oncorhynchus kisutch), rainbow trout (Onchorhynchus mykiss) and brown trout (Salmo trutta), and can cause diseases like heart and skeletal muscle inflammation (HSMI), jaundice syndrome, erythrocyte inclusion body syndrome (EIBS) and proliferative darkening syndrome (PDS). Purified PRV administrated to fish has proven the causality for HSMI and EIBS. During the early peak phase of infection, salmonid erythrocytes are the main virus-replicating cells. In this initial phase, cytoplasmic inclusions called "virus factories" can be observed in the erythrocytes, and are the primary sites for the formation of new virus particles. The PRV-infected erythrocytes in Atlantic salmon mount a strong long-lasting innate antiviral response lasting for many weeks after the onset of infection. The antiviral response of Atlantic salmon erythrocytes involves upregulation of potential inhibitors of translation. In accordance with this, PRV-1 protein production in erythrocytes halts while virus RNA can persist for months. Furthermore, PRV infection in Coho salmon and rainbow trout are associated with anemia, and in Atlantic salmon lower hemoglobin levels are observed. Here we summarize and discuss the recently published findings on PRV infection, replication and effects on salmonid erythrocytes, and discuss how PRV can be a useful tool for the study of innate immune responses in erythrocytes, and help reveal novel immune functions of the red blood cells in fish.
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Affiliation(s)
- Øystein Wessel
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Aleksei Krasnov
- Division of Aquaculture, Norwegian Institute of Fisheries and Aquaculture (Nofima), Tromsø, Norway
| | - Gerrit Timmerhaus
- Division of Aquaculture, Norwegian Institute of Fisheries and Aquaculture (Nofima), Tromsø, Norway
| | - Espen Rimstad
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Maria K Dahle
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway.,The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
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12
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Haatveit HM, Hodneland K, Braaen S, Hansen EF, Nyman IB, Dahle MK, Frost P, Rimstad E. DNA vaccine expressing the non-structural proteins of Piscine orthoreovirus delay the kinetics of PRV infection and induces moderate protection against heart -and skeletal muscle inflammation in Atlantic salmon (Salmo salar). Vaccine 2018; 36:7599-7608. [PMID: 30392768 DOI: 10.1016/j.vaccine.2018.10.094] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 10/23/2018] [Accepted: 10/30/2018] [Indexed: 01/08/2023]
Abstract
Piscine orthoreovirus (PRV) causes heart- and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar). Erythrocytes are the main target cells for PRV. HSMI causes significant economic losses to the salmon aquaculture industry, and there is currently no vaccine available. PRV replicates and assembles within cytoplasmic structures called viral factories, mainly organized by the non-structural viral protein µNS. In two experimental vaccination trials in Atlantic salmon, using DNA vaccines expressing different combinations of PRV proteins, we found that expression of the non-structural proteins µNS combined with the cell attachment protein σ1 was associated with an increasing trend in lymphocyte marker gene expression in spleen, and induced moderate protective effect against HSMI.
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Affiliation(s)
- Hanne M Haatveit
- Department of Food Safety and Infectious Biology, Norwegian University of Life Sciences, 0454 Oslo, Norway
| | | | - Stine Braaen
- Department of Food Safety and Infectious Biology, Norwegian University of Life Sciences, 0454 Oslo, Norway
| | - Elisabeth F Hansen
- Department of Food Safety and Infectious Biology, Norwegian University of Life Sciences, 0454 Oslo, Norway
| | - Ingvild B Nyman
- Department of Food Safety and Infectious Biology, Norwegian University of Life Sciences, 0454 Oslo, Norway
| | | | | | - Espen Rimstad
- Department of Food Safety and Infectious Biology, Norwegian University of Life Sciences, 0454 Oslo, Norway.
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13
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Kuehn R, Stoeckle BC, Young M, Popp L, Taeubert JE, Pfaffl MW, Geist J. Identification of a piscine reovirus-related pathogen in proliferative darkening syndrome (PDS) infected brown trout (Salmo trutta fario) using a next-generation technology detection pipeline. PLoS One 2018; 13:e0206164. [PMID: 30346982 PMCID: PMC6197672 DOI: 10.1371/journal.pone.0206164] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/08/2018] [Indexed: 01/02/2023] Open
Abstract
The proliferative darkening syndrome (PDS) is an annually recurring disease that causes species-specific die-off of brown trout (Salmo trutta fario) with a mortality rate of near 100% in pre-alpine rivers of central Europe. So far the etiology and causation of this disease is still unclear. The objective of this study was to identify the cause of PDS using a next-generation technology detection pipeline. Following the hypothesis that PDS is caused by an infectious agent, brown trout specimens were exposed to water from a heavily affected pre-alpine river with annual occurrence of the disease. Specimens were sampled over the entire time period from potential infection through death. Transcriptomic analysis (microarray) and RT-qPCR of brown trout liver tissue evidenced strong gene expression response of immune-associated genes. Messenger RNA of specimens with synchronous immune expression profiles were ultra-deep sequenced using next-generation sequencing technology (NGS). Bioinformatic processing of generated reads and gap-filling Sanger re-sequencing of the identified pathogen genome revealed strong evidence that a piscine-related reovirus is the causative organism of PDS. The identified pathogen is phylogenetically closely related to the family of piscine reoviruses (PRV) which are considered as the causation of different fish diseases in Atlantic and Pacific salmonid species such as Salmo salar and Onchorhynchus kisutch. This study also highlights that the approach of first screening immune responses along a timeline in order to identify synchronously affected stages in different specimens which subsequently were ultra-deep sequenced is an effective approach in pathogen detection. In particular, the identification of specimens with synchronous molecular immune response patterns combined with NGS sequencing and gap-filling re-sequencing resulted in the successful pathogen detection of PDS.
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Affiliation(s)
- Ralph Kuehn
- Unit of Molecular Zoology, Department of Zoology, Technical University of Munich, Freising, Germany.,Department of Fish, Wildlife and Conservation Ecology, New Mexico State University, Las Cruces, NM, United States of America
| | - Bernhard C Stoeckle
- Unit of Molecular Zoology, Department of Zoology, Technical University of Munich, Freising, Germany.,Aquatic Systems Biology Unit, Department of Ecology and Ecosystem Management, Technical University of Munich, Freising, Germany
| | - Marc Young
- Unit of Molecular Zoology, Department of Zoology, Technical University of Munich, Freising, Germany
| | - Lisa Popp
- Unit of Molecular Zoology, Department of Zoology, Technical University of Munich, Freising, Germany
| | - Jens-Eike Taeubert
- Fachberatung für Fischerei Niederbayern, Bezirk Niederbayern, Landshut, Germany
| | - Michael W Pfaffl
- Department of Animal Physiology and Immunology, Technical University of Munich, Freising, Germany
| | - Juergen Geist
- Aquatic Systems Biology Unit, Department of Ecology and Ecosystem Management, Technical University of Munich, Freising, Germany
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14
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Molecular and Antigenic Characterization of Piscine orthoreovirus (PRV) from Rainbow Trout (Oncorhynchus mykiss). Viruses 2018; 10:v10040170. [PMID: 29614838 PMCID: PMC5923464 DOI: 10.3390/v10040170] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 03/23/2018] [Accepted: 03/28/2018] [Indexed: 01/01/2023] Open
Abstract
Piscine orthoreovirus (PRV-1) causes heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar). Recently, a novel PRV (formerly PRV-Om, here called PRV-3), was found in rainbow trout (Oncorhynchus mykiss) with HSMI-like disease. PRV is considered to be an emerging pathogen in farmed salmonids. In this study, molecular and antigenic characterization of PRV-3 was performed. Erythrocytes are the main target cells for PRV, and blood samples that were collected from experimentally challenged fish were used as source of virus. Virus particles were purified by gradient ultracentrifugation and the complete coding sequences of PRV-3 were obtained by Illumina sequencing. When compared to PRV-1, the nucleotide identity of the coding regions was 80.1%, and the amino acid identities of the predicted PRV-3 proteins varied from 96.7% (λ1) to 79.1% (σ3). Phylogenetic analysis showed that PRV-3 belongs to a separate cluster. The region encoding σ3 were sequenced from PRV-3 isolates collected from rainbow trout in Europe. These sequences clustered together, but were distant from PRV-3 that was isolated from rainbow trout in Norway. Bioinformatic analyses of PRV-3 proteins revealed that predicted secondary structures and functional domains were conserved between PRV-3 and PRV-1. Rabbit antisera raised against purified virus or various recombinant virus proteins from PRV-1 all cross-reacted with PRV-3. Our findings indicate that despite different species preferences of the PRV subtypes, several genetic, antigenic, and structural properties are conserved between PRV-1 and-3.
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15
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Purcell MK, Powers RL, Evered J, Kerwin J, Meyers TR, Stewart B, Winton JR. Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus in Alaska and Washington. JOURNAL OF FISH DISEASES 2018; 41:347-355. [PMID: 29159930 DOI: 10.1111/jfd.12740] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 06/07/2023]
Abstract
This research was initiated in conjunction with a systematic, multiagency surveillance effort in the United States (U.S.) in response to reported findings of infectious salmon anaemia virus (ISAV) RNA in British Columbia, Canada. In the systematic surveillance study reported in a companion paper, tissues from various salmonids taken from Washington and Alaska were surveyed for ISAV RNA using the U.S.-approved diagnostic method, and samples were released for use in this present study only after testing negative. Here, we tested a subset of these samples for ISAV RNA with three additional published molecular assays, as well as for RNA from salmonid alphavirus (SAV), piscine myocarditis virus (PMCV) and piscine orthoreovirus (PRV). All samples (n = 2,252; 121 stock cohorts) tested negative for RNA from ISAV, PMCV, and SAV. In contrast, there were 25 stock cohorts from Washington and Alaska that had one or more individuals test positive for PRV RNA; prevalence within stocks varied and ranged from 2% to 73%. The overall prevalence of PRV RNA-positive individuals across the study was 3.4% (77 of 2,252 fish tested). Findings of PRV RNA were most common in coho (Oncorhynchus kisutch Walbaum) and Chinook (O. tshawytscha Walbaum) salmon.
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Affiliation(s)
- M K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - R L Powers
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - J Evered
- U.S. Fish and Wildlife Service, Olympia Fish Health Center, Lacey, WA, USA
| | - J Kerwin
- Washington Department of Fish and Wildlife, Olympia, WA, USA
| | - T R Meyers
- Division of Commercial Fisheries, Alaska Department of Fish and Game, Juneau, AK, USA
| | - B Stewart
- Northwest Indian Fisheries Commission, Olympia, WA, USA
| | - J R Winton
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
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16
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Tengs T, Rimstad E. Emerging pathogens in the fish farming industry and sequencing-based pathogen discovery. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 75:109-119. [PMID: 28167074 DOI: 10.1016/j.dci.2017.01.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/27/2017] [Accepted: 01/31/2017] [Indexed: 06/06/2023]
Abstract
The use of large scale DNA/RNA sequencing has become an integral part of biomedical research. Reduced sequencing costs and the availability of efficient computational resources has led to a revolution in how problems concerning genomics and transcriptomics are addressed. Sequencing-based pathogen discovery represents one example of how genetic data can now be used in ways that were previously considered infeasible. Emerging pathogens affect both human and animal health due to a multitude of factors, including globalization, a shifting environment and an increasing human population. Fish farming represents a relevant, interesting and challenging system to study emerging pathogens. This review summarizes recent progress in pathogen discovery using sequence data, with particular emphasis on viruses in Atlantic salmon (Salmo salar).
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Affiliation(s)
- Torstein Tengs
- Department of Chemistry, Biotechnology and Food Sciences, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, 1430 Aas, Norway.
| | - Espen Rimstad
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, 0033 Oslo, Norway
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17
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Hauge H, Vendramin N, Taksdal T, Olsen AB, Wessel Ø, Mikkelsen SS, Alencar ALF, Olesen NJ, Dahle MK. Infection experiments with novel Piscine orthoreovirus from rainbow trout (Oncorhynchus mykiss) in salmonids. PLoS One 2017; 12:e0180293. [PMID: 28678799 PMCID: PMC5497981 DOI: 10.1371/journal.pone.0180293] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 06/13/2017] [Indexed: 01/12/2023] Open
Abstract
A new disease in farmed rainbow trout (Onchorhyncus mykiss) was described in Norway in 2013. The disease mainly affected the heart and resembled heart and skeletal muscle inflammation (HSMI) in Atlantic salmon (Salmo salar L.). HSMI is associated with Piscine orthoreovirus (PRV), and a search for a similar virus in the diseased rainbow trout led to detection of a sequence with 85% similarity to PRV. This finding called for a targeted effort to assess the risk the new PRV-variant pose on farmed rainbow trout and Atlantic salmon by studying infection and disease pathogenesis, aiming to provide more diagnostic knowledge. Based on the genetic relationship to PRV, the novel virus is referred to as PRV-Oncorhynchus mykiss (PRV-Om) in contrast to PRV-Salmo salar (PRV-Ss). In experimental trials, intraperitoneally injected PRV-Om was shown to replicate in blood in both salmonid species, but more effectively in rainbow trout. In rainbow trout, the virus levels peaked in blood and heart of cohabitants 6 weeks post challenge, along with increased expression of antiviral genes (Mx and viperin) in the spleen, with 80-100% of the cohabitants infected. Heart inflammation was diagnosed in all cohabitants examined 8 weeks post challenge. In contrast, less than 50% of the Atlantic salmon cohabitants were infected between 8 and 16 weeks post challenge and the antiviral response in these fish was very low. From 12 weeks post challenge and onwards, mild focal myocarditis was demonstrated in a few virus-positive salmon. In conclusion, PRV-Om infects both salmonid species, but faster transmission, more notable antiviral response and more prominent heart pathology were observed in rainbow trout.
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Affiliation(s)
- Helena Hauge
- Norwegian Veterinary Institute, Oslo & Bergen, Norway
| | - Niccolo Vendramin
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | | | | | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | | | | | - Niels Jørgen Olesen
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
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18
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Teige LH, Lund M, Haatveit HM, Røsæg MV, Wessel Ø, Dahle MK, Storset AK. A bead based multiplex immunoassay detects Piscine orthoreovirus specific antibodies in Atlantic salmon (Salmo salar). FISH & SHELLFISH IMMUNOLOGY 2017; 63:491-499. [PMID: 28254501 DOI: 10.1016/j.fsi.2017.02.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/16/2017] [Accepted: 02/24/2017] [Indexed: 06/06/2023]
Abstract
Future growth in aquaculture relies strongly on the control of diseases and pathogens. Vaccination has been a successful strategy for obtaining control of bacterial diseases in fish, but for viral diseases, vaccine development has been more challenging. Effective long-term protection against viral infections is not yet fully understood for fish, and in addition, optimal tools to monitor adaptive immunity are limited. Assays that can detect specific antibodies produced in response to viral infection in fish are still in their early development. Multiplex bead based assays have many advantages over traditional assays, since they are more sensitive and allow detection of multiple antigen-specific antibodies simultaneously in very small amounts of plasma or serum. In the present study, a bead based assay have been developed for detection of plasma IgM directed against Piscine orthoreovirus (PRV), the virus associated with the disease Heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon. Using recombinant PRV proteins coated on beads, antibodies targeting the structural outer capsid protein μ1 and the non-structural protein μNS were detected. Results from a PRV cohabitation challenge trial indicated that the antibody production was initiated approximately two weeks after the peak phase of PRV infection, coinciding with typical HSMI pathology. Thereafter, the antibody production increased while the epicardial inflammation became less prominent. In conclusion, the novel assay can detect PRV-specific antibodies that may play a role in viral defence. The bead-based immunoassay represents a valuable tool for studies on HSMI and possibly other diseases in aquaculture.
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Affiliation(s)
- Lena Hammerlund Teige
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, N-0454 Oslo, Norway
| | - Morten Lund
- Norwegian Veterinary Institute, N-0454 Oslo, Norway
| | - Hanne M Haatveit
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, N-0454 Oslo, Norway
| | - Magnus Vikan Røsæg
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, N-0454 Oslo, Norway; SalMar ASA, N-7266 Kverva, Norway
| | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, N-0454 Oslo, Norway
| | - Maria K Dahle
- Norwegian Veterinary Institute, N-0454 Oslo, Norway.
| | - Anne K Storset
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, N-0454 Oslo, Norway
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19
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Virus-mediated suppression of host non-self recognition facilitates horizontal transmission of heterologous viruses. PLoS Pathog 2017; 13:e1006234. [PMID: 28334041 PMCID: PMC5363999 DOI: 10.1371/journal.ppat.1006234] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/10/2017] [Indexed: 02/06/2023] Open
Abstract
Non-self recognition is a common phenomenon among organisms; it often leads to innate immunity to prevent the invasion of parasites and maintain the genetic polymorphism of organisms. Fungal vegetative incompatibility is a type of non-self recognition which often induces programmed cell death (PCD) and restricts the spread of molecular parasites. It is not clearly known whether virus infection could attenuate non-self recognition among host individuals to facilitate its spread. Here, we report that a hypovirulence-associated mycoreovirus, named Sclerotinia sclerotiorum mycoreovirus 4 (SsMYRV4), could suppress host non-self recognition and facilitate horizontal transmission of heterologous viruses. We found that cell death in intermingled colony regions between SsMYRV4-infected Sclerotinia sclerotiorum strain and other tested vegetatively incompatible strains was markedly reduced and inhibition barrage lines were not clearly observed. Vegetative incompatibility, which involves Heterotrimeric guanine nucleotide-binding proteins (G proteins) signaling pathway, is controlled by specific loci termed het (heterokaryon incompatibility) loci. Reactive oxygen species (ROS) plays a key role in vegetative incompatibility-mediated PCD. The expression of G protein subunit genes, het genes, and ROS-related genes were significantly down-regulated, and cellular production of ROS was suppressed in the presence of SsMYRV4. Furthermore, SsMYRV4-infected strain could easily accept other viruses through hyphal contact and these viruses could be efficiently transmitted from SsMYRV4-infected strain to other vegetatively incompatible individuals. Thus, we concluded that SsMYRV4 is capable of suppressing host non-self recognition and facilitating heterologous viruses transmission among host individuals. These findings may enhance our understanding of virus ecology, and provide a potential strategy to utilize hypovirulence-associated mycoviruses to control fungal diseases.
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20
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Haatveit HM, Wessel Ø, Markussen T, Lund M, Thiede B, Nyman IB, Braaen S, Dahle MK, Rimstad E. Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells. Viruses 2017; 9:E49. [PMID: 28335455 PMCID: PMC5371804 DOI: 10.3390/v9030049] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/07/2017] [Accepted: 03/10/2017] [Indexed: 01/12/2023] Open
Abstract
Piscine orthoreovirus (PRV) is ubiquitous in farmed Atlantic salmon (Salmo salar) and the cause of heart and skeletal muscle inflammation. Erythrocytes are important target cells for PRV. We have investigated the kinetics of PRV infection in salmon blood cells. The findings indicate that PRV causes an acute infection of blood cells lasting 1-2 weeks, before it subsides into persistence. A high production of viral proteins occurred initially in the acute phase which significantly correlated with antiviral gene transcription. Globular viral factories organized by the non-structural protein µNS were also observed initially, but were not evident at later stages. Interactions between µNS and the PRV structural proteins λ1, µ1, σ1 and σ3 were demonstrated. Different size variants of µNS and the outer capsid protein µ1 appeared at specific time points during infection. Maximal viral protein load was observed five weeks post cohabitant challenge and was undetectable from seven weeks post challenge. In contrast, viral RNA at a high level could be detected throughout the eight-week trial. A proteolytic cleavage fragment of the µ1 protein was the only viral protein detectable after seven weeks post challenge, indicating that this µ1 fragment may be involved in the mechanisms of persistent infection.
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Affiliation(s)
- Hanne Merethe Haatveit
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Øystein Wessel
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Turhan Markussen
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Morten Lund
- Department of Immunology, Norwegian Veterinary Institute, 0454 Oslo, Norway.
| | - Bernd Thiede
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
| | - Ingvild Berg Nyman
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Stine Braaen
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Maria Krudtaa Dahle
- Department of Immunology, Norwegian Veterinary Institute, 0454 Oslo, Norway.
| | - Espen Rimstad
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
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21
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Bjørgen H, Wessel Ø, Fjelldal PG, Hansen T, Sveier H, Sæbø HR, Enger KB, Monsen E, Kvellestad A, Rimstad E, Koppang EO. Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar). Vet Res 2015; 46:89. [PMID: 26346256 PMCID: PMC4562189 DOI: 10.1186/s13567-015-0244-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/17/2015] [Indexed: 11/10/2022] Open
Abstract
Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.
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Affiliation(s)
- Håvard Bjørgen
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Øystein Wessel
- Institute of Food Safety and Infection Biology, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | | | - Tom Hansen
- Matre Research Station, Institute of Marine Research, Matre, Norway.
| | | | - Håkon Rydland Sæbø
- Department Brandasund and Rex Star, Lerøy Sjøtroll AS, Skjervøy, Norway.
| | | | | | - Agnar Kvellestad
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Espen Rimstad
- Institute of Food Safety and Infection Biology, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Erling Olaf Koppang
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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