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Nielsen SS, Alvarez J, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar C, Herskin MS, Michel V, Miranda Chueca MÁ, Padalino B, Roberts HC, Spoolder H, Ståhl K, Velarde A, Viltrop A, Winckler C, Bron J, Olesen NJ, Sindre H, Stone D, Vendramin N, Antoniou SE, Broglia A, Karagianni AE, Papanikolaou A, Bicout DJ. Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU)2016/429): Infection with salmonid alphavirus (SAV). EFSA J 2023; 21:e08327. [PMID: 37908450 PMCID: PMC10613945 DOI: 10.2903/j.efsa.2023.8327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
Infection with salmonid alphavirus (SAV) was assessed according to the criteria of the Animal Health Law (AHL), in particular the criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as laid out in Article 9 and Article 8 for listing animal species related to infection with SAV. The assessment was performed following the ad hoc method on data collection and assessment developed by AHAW Panel and already published. The outcome reported is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with an uncertain outcome. According to the assessment, it was uncertain whether infection with salmonid alphavirus can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (50-80% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that infection with salmonid alphavirus does not meet the criteria in Section 1 (Category A; 5-10% probability of meeting the criteria) and it is uncertain whether it meets the criteria in Sections 2, 3, 4 and 5 (Categories B, C, D and E; 50-90%, probability of meeting the criteria). The animal species to be listed for infection with SAV according to Article 8 criteria are provided.
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Kim KH, Kang G, Woo WS, Sohn MY, Son HJ, Kwon MG, Kim JO, Park CI. Red Sea Bream Iridovirus Kinetics, Tissue Tropism, and Interspecies Horizontal Transmission in Flathead Grey Mullets ( Mugil cephalus). Animals (Basel) 2023; 13:ani13081341. [PMID: 37106904 PMCID: PMC10135084 DOI: 10.3390/ani13081341] [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: 03/25/2023] [Revised: 04/12/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Red sea bream iridovirus (RSIV) causes significant economic losses in the aquaculture industry. We analyzed the pathogenicity of RSIV in flathead grey mullets (Mugil cephalus), the correlation of histopathological lesions, and interspecies horizontal transmission, through immersion infection and cohabitation challenges. Flathead grey mullets, which were challenged by immersion infection, exhibited mortality at 14 and 24 days after RSIV exposure. Viral shedding in seawater peaked 2-3 days before or after the observed mortality. Specific lesions of RSIV were observed in the spleen and kidney, and the correlation between histopathological grade and viral load was the highest in the spleen. In a cohabitation challenge, flathead grey mullets were the donors, and healthy rock bream, red sea bream, and flathead grey mullets were the recipients. Viral shedding in seawater was the highest in flathead grey mullet and rock bream at 25 °C, with 106.0 RSIV copies L/g at 14 dpi. No mortality was observed in any group challenged at 15 °C, and no RSIV was detected in seawater after 30 dpi. The virus shed from RSIV-infected flathead grey mullets caused horizontal transmission through seawater. These findings suggest that rapid decision-making is warranted when managing disease in fish farms.
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Affiliation(s)
- Kyung-Ho Kim
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
| | - Gyoungsik Kang
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
| | - Won-Sik Woo
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
| | - Min-Young Sohn
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
| | - Ha-Jeong Son
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
| | - Mun-Gyeong Kwon
- Aquatic Disease Control Division, National Fishery Products Quality Management Service, 216, Gijanghaean-ro, Gijang, Busan 46083, Republic of Korea
| | - Jae-Ok Kim
- Aquatic Disease Control Division, National Fishery Products Quality Management Service, 17, Jungnim 2-ro, Tongyeong 53019, Republic of Korea
| | - Chan-Il Park
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Republic of Korea
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Fritsvold C, Mikalsen AB, Haugland Ø, Tartor H, Sindre H. Characterization of early phases of cardiomyopathy syndrome pathogenesis in Atlantic salmon (Salmo salar L.) through various diagnostic methods. JOURNAL OF FISH DISEASES 2022; 45:1267-1279. [PMID: 35686455 PMCID: PMC9543292 DOI: 10.1111/jfd.13659] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 04/19/2022] [Accepted: 04/21/2022] [Indexed: 06/15/2023]
Abstract
Since the first description of cardiomyopathy syndrome (CMS) in Atlantic salmon, in 1985, the disease caused by piscine myocarditisvirus (PMCV) has become a common problem in Atlantic salmon farming, not only in Norway, but also in other salmon farming countries like Scotland and Ireland. In the last years, CMS has been ranked as the most important salmon viral disease in Norway regarding both mortality and economic losses. Detailed knowledge of infection and pathogenesis is still lacking, a decade after the causal agent was first described, and there is a need for a wider range of methods/tools for diagnostic and research purposes. In this study, we compared the detection of PMCV- and CMS-related tissue lesions using previously used and well-known methods like histopathology and real-time RT-PCR to immunohistochemistry (IHC), a less used method, and a new method, RNAscope in situ hybridization. Tissue samples of three different cardiac compartments, mid-kidney and skin/muscle tissue were compared with non-lethal parallel samplings of blood and mucus. The development of pathological cardiac lesions observed in this experiment was in accordance with previous descriptions of CMS. Our results indicate a viremic phase 10- to 20-day post-challenge (dpc) preceding the cardiac lesions. In this early phase, virus could also be detected in relatively high amount in mid-kidney by real-time RT-PCR. Plasma and/or mid-kidney samples may, therefore, be candidates to screen for early-phase PMCV infection. The RNAscope in situ hybridization method showed higher sensitivity and robustness compared with the immunohistochemistry and may be a valuable support to histopathology in CMS diagnostics, especially in cases of untypical lesions or mixed infections.
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Affiliation(s)
| | - Aase B. Mikalsen
- Faculty of Veterinary MedicineNorwegian University of Life SciencesÅsNorway
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Kim KH, Choi KM, Joo MS, Kang G, Woo WS, Sohn MY, Son HJ, Kwon MG, Kim JO, Kim DH, Park CI. Red Sea Bream Iridovirus (RSIV) Kinetics in Rock Bream (Oplegnathus fasciatus) at Various Fish-Rearing Seawater Temperatures. Animals (Basel) 2022; 12:ani12151978. [PMID: 35953967 PMCID: PMC9367270 DOI: 10.3390/ani12151978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 11/20/2022] Open
Abstract
Simple Summary Red sea bream iridoviral disease (RSIVD) generates serious economic losses by causing mass mortality events of rock bream during the season with high water temperature in the Republic of Korea and other Asian countries. However, very few studies have investigated RSIV kinetics in rock bream under various rearing water temperatures. In this paper, we investigated the viral load shedding of RSIV into seawater after artificially infecting rock bream (Oplegnathus fasciatus) with the virus. Overall, our data suggest that the viral load shedding of RSIV into seawater varies depending on water temperature and virus inoculation concentration. Our results reveal the potential of non-invasive virus detection approaches, such as the utilization of environmental DNA in fish farms. In addition, we showed that the quantitative analysis of seawater viruses can indirectly improve our understanding of disease progression in fish, potentially contributing to enhanced disease control. Abstract Red sea bream iridoviral disease (RSIVD) causes serious economic losses in the aquaculture industry. In this paper, we evaluated RSIV kinetics in rock bream under various rearing water temperatures and different RSIV inoculation concentrations. High viral copy numbers (approximately 103.7–106.7 RSIV genome copies/L/g) were observed during the period of active fish mortality after RSIV infection at all concentrations in the tanks (25 °C and 20 °C). In the group injected with 104 RSIV genome copies/fish, RSIV was not detected at 21–30 days post-infection (dpi) in the rearing seawater. In rock bream infected at 15 °C and subjected to increasing water temperature (1 °C/d until 25 °C) 3 days later, the virus replication rate and number of viral copies shed into the rearing seawater increased. With the decrease in temperature (1 °C/d) from 25 to 15 °C after the infection, the virus replicated rapidly and was released at high loads on the initial 3–5 dpi, whereas the number of viral copies in the fish and seawater decreased after 14 dpi. These results indicate that the number of viral copies shed into the rearing seawater varies depending on the RSIV infection level in rock bream.
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Affiliation(s)
- Kyung-Ho Kim
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Kwang-Min Choi
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Min-Soo Joo
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Gyoungsik Kang
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Won-Sik Woo
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Min-Young Sohn
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Ha-Jeong Son
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
| | - Mun-Gyeong Kwon
- Aquatic Disease Control Division, National Fishery Products Quality Management Service, 216, Gijanghaean-ro, Gijang, Busan 46083, Korea
| | - Jae-Ok Kim
- Aquatic Disease Control Division, National Fishery Products Quality Management Service, 17, Jungnim 2-ro, Tongyeong 53019, Korea
| | - Do-Hyung Kim
- Department of Aquatic Life Medicine, College of Fisheries Science, Pukyong National University, 45, Yongso-ro, Nam-Gu, Busan 48513, Korea
- Correspondence: (D.-H.K.); (C.-I.P.); Tel.: +82-55-772-9153 (C.-I.P.)
| | - Chan-Il Park
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 2, Tongyeonghaean-ro, Tongyeong 53064, Korea
- Correspondence: (D.-H.K.); (C.-I.P.); Tel.: +82-55-772-9153 (C.-I.P.)
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Holen E, Chen M, Fjelldal PG, Skjærven K, Sissener NH, Remø S, Prabhu AJ, Hamre K, Vikeså V, Subramanian S, Espe M. Tailoring freshwater diets towards boosted immunity and pancreas disease infection robustness in Atlantic salmon post smolts. FISH & SHELLFISH IMMUNOLOGY 2022; 120:377-391. [PMID: 34808357 DOI: 10.1016/j.fsi.2021.11.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
The aim of the current study was to investigate how freshwater diets impact on immunity in Atlantic salmon smolts in freshwater, during transfer to seawater and in post smolts during the seawater stage with and without pancreas disease (PD) infection. Three specific freshwater diets were prepared: (i) A diet similar in composition to commercial salmon freshwater diets (Standard diet); (ii) A diet composed of vegetable oils (rapeseed, palm and linseed oils) mimicking the fat composition in aquatic insects - the natural diet of wild salmon in freshwater (Fatty acid diet); (iii) A diet enriched with possible immune modulating amino acids including dl-methionine, l-lysine, l-threonine and taurine (Amino acid diet). After seawater transfer, all fish were fed the same commercial diet. Head kidneys were extracted, and their leukocytes isolated from smolts right before transfer to seawater, from post smolts one and six weeks after transfer to seawater, and from post smolts in seawater after 8 weeks of ongoing PD infection. In addition, to provoke bacterial or virus induced inflammation in vitro, the individual leukocyte suspension from all fish were stimulated by lipopolysaccharide (LPS) or polyinosinic acid: polycytidylic acid (PIC). The transfer of smolts from fresh-to seawater changed the transcription of several types of genes. Particularly in isolates from fish fed the Standard or Fatty acid diet in freshwater, overall gene transcription (IL-1β, CD83, INF-γ, cox2, cd36, MGAT2, catalase) declined. However, the Amino acid diet stimulated the LPS induced gene transcription of IL-1β, CD83, Cox2, and INF-γ at this stage. In freshwater smolts, PIC stimulated leukocytes showed higher transcription level of Mx and viperin in the Fatty acid and Amino acid diet groups compared to the Standard diet group. In seawater post smolts, Mx and viperin responded similarly to PIC challenge in all diet groups. Furthermore, leukocytes isolated from PD infected fish, continued responding to PIC, regardless of freshwater diet.
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Affiliation(s)
- E Holen
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway.
| | - M Chen
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway; Institute of Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, China
| | - P G Fjelldal
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - K Skjærven
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - N H Sissener
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - S Remø
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - A J Prabhu
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - K Hamre
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
| | - V Vikeså
- Skretting ARC, Sjøhagen 3, 4026, Stavanger, Norway
| | | | - M Espe
- Institute of Marine Research, Postboks 1870, Nordnes, 5817, Bergen, Norway
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6
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Røsæg MV, Thorarinsson R, Aunsmo A. Effect of vaccines against pancreas disease in farmed Atlantic salmon. JOURNAL OF FISH DISEASES 2021; 44:1911-1924. [PMID: 34402092 PMCID: PMC9291808 DOI: 10.1111/jfd.13505] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 05/19/2023]
Abstract
Pancreas disease (PD) caused by salmonid alphavirus (SAV) continues to negatively impact salmon farming. To assess the effect on growth and mortality of three vaccines against PD, two controlled field designs were employed: one controlled field study with individual marked fish (PIT tag) assessing three PD vaccines and three controls groups, and a second controlled field study with group marked fish (Maxilla) comparing two PD vaccines against controls. In addition, a descriptive study using whole cages compared fish immunized with two different PD vaccines against controls. The target populations experienced a natural PD outbreak where both SAV 2 and SAV 3 were identified. Only one of the PD vaccines provided statistically significant improvements in harvest weight of 0.43 kg (CI: 0.29-0.57) and 0.51 kg (CI: 0.36-0.65) compared with the control in the PIT tag and the Maxilla study, respectively. In the latter, a significant reduction in mortality of 1.31 (CI:0.8-1.8) per cent points was registered for the same vaccine compared with controls. These results aligned with the growth and PD-specific mortality registered in the descriptive Cage study. The data in this study show a difference in the efficacy of PD vaccines in farmed Atlantic salmon.
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Affiliation(s)
| | | | - Arnfinn Aunsmo
- Faculty of Veterinary MedicineUniversity of Life SciencesOsloNorway
- Present address:
Laxar fiskeldi ehfEskifjörðurIceland
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Noguera P, Klinger M, Örün H, Grunow B, Del-Pozo J. Ultrastructural insights into the replication cycle of salmon pancreas disease virus (SPDV) using salmon cardiac primary cultures (SCPCs). JOURNAL OF FISH DISEASES 2021; 44:2031-2041. [PMID: 34424537 DOI: 10.1111/jfd.13518] [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: 05/13/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Salmon pancreas disease virus (SPDV) has been affecting the salmon farming industry for over 30 years, but despite the substantial amount of studies, there are still a number of recognized knowledge gaps, for example in the transmission of the virus. In this work, an ultrastructural morphological approach was used to describe observations after infection by SPDV of an ex vivo cardiac model generated from Atlantic salmon embryos. The observations in this study and those available on previous ultrastructural work on SPDV are compared and contrasted with the current knowledge on terrestrial mammalian and insect alphaviral replication cycles, which is deeper than that of SPDV both morphologically and mechanistically. Despite their limitations, morphological descriptions remain an excellent way to generate novel hypotheses, and this has been the aim of this work. This study has used a target host, ex vivo model and resulted in some previously undescribed features, including filopodial membrane projections, cytoplasmic stress granules or putative intracytoplasmic budding. The latter suggests a new hypothesis that warrants further mechanistic research: SPDV in salmon may have retained the capacity for non-cytolytic (persistent) infections by intracellular budding, similar to that noted in arthropod vectors of other alphaviruses. In the notable absence of a known intermediate host for SPDV, the presence of this pattern suggests that both cytopathic and persistent infections may coexist in the same host. It is our hope that the ultrastructural comparison presented here stimulates new research that brings the knowledge on SPDV replication cycle up to a similar level to that of terrestrial alphaviruses.
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Affiliation(s)
| | | | - Histro Örün
- Institute of Anatomy, University of Lübeck, Lübeck, Germany
| | - Bianka Grunow
- Leibniz-Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Jorge Del-Pozo
- Royal Dick School of Veterinary Sciences, University of Edinburgh, Roslin, UK
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8
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Bernhardt LV, Myrmel M, Lillehaug A, Qviller L, Chioma Weli S. Filtration, concentration and detection of salmonid alphavirus in seawater during a post-smolt salmon (Salmo salar) cohabitant challenge. DISEASES OF AQUATIC ORGANISMS 2021; 144:61-73. [PMID: 33764314 DOI: 10.3354/dao03572] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Currently, the prevalence of salmonid alphavirus (SAV) in Norwegian Atlantic salmon farms is largely surveyed via sacrificing fish and sampling of organ tissue on a monthly basis. However, a more cost-efficient, straightforward, rapid, reliable, reproducible and animal welfare friendly method based on the detection of SAV in water could be considered as an alternative method. In the present study, such a method was developed and optimized through a 6 wk cohabitant challenge trial, using post-smolt Atlantic salmon Salmo salar L challenged with high or low doses of SAV subtype 3 (SAV3). Tank water and tissue samples from cohabitant fish were collected at 16 time points. SAV3 was concentrated from the water by filtration, using either electronegative or electropositive membrane filters, which were subsequently rinsed with one of 4 different buffer solutions. SAV3 was detected first in tank water (7 d post-challenge, DPC), and later in cohabitant fish organ tissue samples (12 DPC). The electronegative filter (MF-Millipore™) and rinsing with NucliSENS® easyMAG® Lysis Buffer presented the best SAV3 recovery. A significant positive correlation was found between SAV3 in the tank water concentrates and the mid-kidney samples. Based on these results, detection of SAV3 in filtrated seawater is believed to have the potential to serve as an alternative method for surveillance of SAV in Atlantic salmon farms.
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9
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Non-Lethal Sequential Individual Monitoring of Viremia in Relation to DNA Vaccination in Fish-Example Using a Salmon Alphavirus DNA Vaccine in Atlantic Salmon Salmo salar. Vaccines (Basel) 2021; 9:vaccines9020163. [PMID: 33671162 PMCID: PMC7922653 DOI: 10.3390/vaccines9020163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/04/2021] [Accepted: 02/04/2021] [Indexed: 11/26/2022] Open
Abstract
Traditionally, commercial testing for vaccine efficacy has relied on the mass infection of vaccinated and unvaccinated animals and the comparison of mortality prevalence and incidence. For some infection models where disease does not cause mortality this approach to testing vaccine efficacy is not useful. Additionally, in fish experimental studies on vaccine efficacy and immune response the norm is that several individuals are lethally sampled at sequential timepoints, and results are extrapolated to represent the kinetics of immune and disease parameters of an individual fish over the entire experimental infection period. In the present study we developed a new approach to vaccine testing for viremic viruses in fish by following the same individuals over the course of a DNA vaccination and experimental infection through repeated blood collection and analyses. Injectable DNA vaccines are particularly efficient against viral disease in fish. To date, two DNA vaccines have been authorised for use in fish farming, one in Canada against Infectious Haemorrhagic Necrotic virus and more recently one in Europe against Salmon Pancreatic Disease virus (SPDv) subtype 3. In the current study we engineered and used an experimental DNA vaccine against SPDv subtype 1. We measured viremia using a reporter cell line system and demonstrated that the viremia phase was completely extinguished following DNA vaccination. Differences in viremia infection kinetics between fish in the placebo group could be related to subsequent antibody levels in the individual fish, with higher antibody levels at terminal sampling in fish showing earlier viremia peaks. The results indicate that sequential non-lethal sampling can highlight associations between infection traits and immune responses measured at asynchronous timepoints and, can provide biological explanations for variation in data. Similar to results observed for the SPDv subtype 3 DNA vaccine, the SPDv subtype 1 DNA vaccine also induced an interferon type 1 response after vaccination and provided high protection against SPDv under laboratory conditions when fish were challenged at 7 weeks post-vaccination.
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Veenstra KA, Hodneland K, Fischer S, Takehana K, Belmonte R, Fischer U. Cellular Immune Responses in Rainbow Trout ( Onchorhynchus mykiss) Following Vaccination and Challenge Against Salmonid Alphavirus (SAV). Vaccines (Basel) 2020; 8:vaccines8040725. [PMID: 33276596 PMCID: PMC7761581 DOI: 10.3390/vaccines8040725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/23/2020] [Accepted: 11/27/2020] [Indexed: 01/25/2023] Open
Abstract
Viral disease outbreaks remain a significant limiting factor for aquaculture. The majority of licensed vaccines used in the industry are administered as oil-adjuvanted formulations carrying inactivated whole pathogens. Cell-mediated immune responses, in particular those based on virus-specific cytotoxic T-cells (CTLs) to conventional inactivated oil-based vaccines, are largely unexplored. As vaccines cannot be optimized against viral pathogens if knowledge of host cellular immune mechanisms remains unknown, in this study we examined fundamental cell-mediated immune responses after vaccination of rainbow trout with an oil-adjuvanted inactivated vaccine against salmonid alphavirus (SAV) and after infection with SAV. A unique in vitro model system was developed to examine MHC class I restricted CTL responses in a clonal line of rainbow trout. The levels of cell-mediated cytotoxicity were compared to pathology, virus load, specific antibody response, changes in immune cell populations, and mRNA expression. Our results hint that different protective mechanisms are being triggered by infection compared to vaccination. While vaccination itself did not cause a strong cytotoxic or humoral response, subsequent challenge of vaccinated fish resulted in significantly stronger and faster specific cytotoxicity, alongside reduced viral titers and pathology. Hence, testing a vaccine on the capacity to induce cell-mediated cytotoxicity will still require a challenge test. Examination of cellular markers additionally indicates that the initial innate response induced by the vaccine could play an important role in steering adaptive mechanisms.
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Affiliation(s)
- Kimberly A. Veenstra
- Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Institute of Infectology, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (K.A.V.); (S.F.)
| | - Kjartan Hodneland
- MSD Animal Health Innovation, Thormøhlens Gate 55, 5006 Bergen, Norway; (K.H.); (R.B.)
| | - Susanne Fischer
- Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Institute of Infectology, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (K.A.V.); (S.F.)
| | - Kota Takehana
- Nagano Prefectural Fisheries Experimental Station, 2871 Oaza-Nakagawate, Akashina, Azumino-shi, Nagano 399-7102, Japan;
| | - Rodrigo Belmonte
- MSD Animal Health Innovation, Thormøhlens Gate 55, 5006 Bergen, Norway; (K.H.); (R.B.)
| | - Uwe Fischer
- Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Institute of Infectology, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (K.A.V.); (S.F.)
- Correspondence: ; Tel.: +49-38351-71175
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11
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Mandal SC, Weidmann M, Albalat A, Carrick E, Morro B, MacKenzie S. Polarized Trout Epithelial Cells Regulate Transepithelial Electrical Resistance, Gene Expression, and the Phosphoproteome in Response to Viral Infection. Front Immunol 2020; 11:1809. [PMID: 32922394 PMCID: PMC7456818 DOI: 10.3389/fimmu.2020.01809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 07/07/2020] [Indexed: 11/13/2022] Open
Abstract
The burden of disease is a major challenge in aquaculture production. The fish gill characterized with a large surface area and short route to the bloodstream is a major environmental interface and a significant portal of entry for pathogens. To investigate gill responses to viral infection the salmonid gill cell line RTgill-W1 was stimulated with synthetic dsRNA and the salmonid alphavirus subtype 2 (SAV-2). Epithelial integrity in polarized cells can be measured as transepithelial electrical resistance (TEER) which is defined as the electrical resistance across a cell monolayer. TEER is a widely accepted quantitative measure of cellular integrity of a cell monolayer. TEER increased immediately after stimulation with the synthetic dsRNA, polyinosinic:polycytidylic acid (poly(I:C)). In parallel, tight junction and gene expression of innate immune activation markers was modulated in response to poly(I:C). The SAV-2 virus was found to replicate at a low level in RTgill-W1 cells where TEER was disturbed at an early stage of infection, however, gene expression related to tight junction regulation was not modulated. A strong poly(I:C)-driven antiviral response was observed including increases of Rig-like receptors (RLRs) and interferon stimulating genes (ISGs) mRNAs. At the level of signal transduction, poly(I:C) stimulation was accompanied by the phosphorylation of 671 proteins, of which 390 were activated solely in response to the presence of poly(I:C). According to motif analysis, kinases in this group included MAPKs, Ca2+/calmodulin-dependent kinase (CaMK) and cAMP-dependent protein kinase (PKA), all reported to be activated in response to viral infection in mammals. Results also highlighted an activation of the cytoskeletal organization that could be mediated by members of the integrin family. While further work is needed to validate these results, our data indicate that salmonid gill epithelia has the ability to mount a significant response to viral infection which might be important in disease progression. In vitro cell culture can facilitate both a deeper understanding of the anti-viral response in fish and open novel therapeutic avenues for fish health management in aquaculture.
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Affiliation(s)
- Shankar C Mandal
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom.,Department of Fisheries, University of Dhaka, Dhaka, Bangladesh
| | - Manfred Weidmann
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Amaya Albalat
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Emma Carrick
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Bernat Morro
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Simon MacKenzie
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
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12
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Quantitative trait loci and genes associated with salmonid alphavirus load in Atlantic salmon: implications for pancreas disease resistance and tolerance. Sci Rep 2020; 10:10393. [PMID: 32587341 PMCID: PMC7316828 DOI: 10.1038/s41598-020-67405-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 06/08/2020] [Indexed: 12/22/2022] Open
Abstract
Salmonid alphavirus infection results in pancreas disease causing severe economic losses for Atlantic salmon aquaculture. Knowledge about genes and pathways contributing to resistance is limited. A 54 K SNP panel was used to genotype 10 full-sibling families each consisting of ~ 110 offspring challenged with salmonid alphavirus subtype 3. Relative heart viral load was assessed at 4- and 10-weeks post-infection using quantitative PCR. A moderate genomic heritability of viral load at 4 weeks (0.15–0.21) and a high positive correlation with survival (0.91–0.98) were detected. Positions of QTL detected on chromosome 3 matched those for survival detected by other studies. The SNP of highest significance occurred in the 3′ untranslated region of gig1, a fish-specific antiviral effector. Locus B of immunoglobulin heavy chain mapped to an area containing multiple SNPs with genome-wide association. Heart mRNA-seq comparing parr from families with high- versus low-genomic breeding value, and matching sample genotypes for SNPs, identified two eQTL for salmonid alphavirus load. Immune genes associated with trans-eQTL were numerous and spread throughout the genome. QTL regions contained several genes with known or predicted immune functions, some differentially expressed. The putative functional genes and variants identified could help improve marker-based selection for pancreas disease resistance.
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13
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Røsæg MV, Garseth ÅH, Brynildsrud OB, Jansen MD. Pancreas disease caused by Salmonid alphavirus subtype 2 reduces growth and feed conversion in farmed Atlantic salmon. Prev Vet Med 2019; 169:104699. [PMID: 31311646 DOI: 10.1016/j.prevetmed.2019.104699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 10/26/2022]
Abstract
Pancreas disease (PD), caused by several subtypes of salmonid alphavirus (SAV), is associated with significant economic losses in European salmonid aquaculture. In this retrospective cohort study, we investigate the impact of PD caused by SAV subtype 2 (SAV2) on growth, feed conversion, and mortality in farmed Atlantic salmon (Salmo salar L.). The study was based on harvest data from a large salmon farming company operating in the SAV2 endemic area of Norway. Mixed-effect regression analyses showed a severe impact on both growth and feed conversion when PD appeared late in the production cycle. In a scenario with fixed slaughter time the estimated impact corresponded to a growth reduction of 0.7 kg and 0.07 points increase in feed conversion ratio. No effect on mortality was observed in this data set. In conclusion, the most important consequences of PD caused by SAV2 infection is reduced growth and feed conversion in large Atlantic salmon. The lack of effect on mortality in this study may be due to other factors overshadowing the impact of PD.
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Affiliation(s)
- Magnus Vikan Røsæg
- SalMar Farming AS, Brattørkaia 15B, 7010 Trondheim, Norway; Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Ullevålsveien 72, 0454 Oslo, Norway.
| | | | - Ola Brønstad Brynildsrud
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Ullevålsveien 72, 0454 Oslo, Norway; Infectious Diseases Epidemiology and Modelling, Norwegian Institute of Public Health, Lovisenbergsgata 8, 0456 Oslo, Norway
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14
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Dessen J, Mørkøre T, Bildøy JI, Johnsen SN, Poppe LT, Hatlen B, Thomassen MS, Rørvik K. Increased dietary protein-to-lipid ratio improves survival during naturally occurring pancreas disease in Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2019; 42:21-34. [PMID: 30311660 PMCID: PMC6988130 DOI: 10.1111/jfd.12904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 08/30/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
This study demonstrated that increased dietary protein-to-lipid ratio (P/L-ratio) improved survival of farmed Atlantic salmon naturally affected by pancreas disease (PD). In addition to diet, body weight (BW) and delousing mortality prior to the PD outbreak also contributed significantly (p < 0.05) to explain the observed variation in PD-associated mortality. Subsequent to the PD outbreak, large amount of fish failed to grow and caused thin fish with poor condition (runts). At the end of the trial, significantly (p < 0.05) lower amounts of runt fish and increased amount of superior graded fish where detected among fish fed increased P/L-ratio and within the fish with the largest BWs prior to PD. Diet, BW and delousing mortality contributed significantly (p < 0.05) to explain the variation in the amount of superior graded fish, whereas BW and diet explained the variation in the amount of runt fish. A significant (p < 0.01) negative linear relationship was observed between the amount of superior graded fish and the total mortality, whereas a positive linear relationship was detected between percentage of fillets with melanin and the total mortality. Thus, increased dietary P/L-ratio seem to reduce the mortality and impaired slaughter quality associated with PD.
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Affiliation(s)
- Jens‐Erik Dessen
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | - Turid Mørkøre
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | | | | | | | | | - Magny S. Thomassen
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | - Kjell‐Arne Rørvik
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
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15
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Ruane NM, Swords D, Morrissey T, Geary M, Hickey C, Collins EM, Geoghegan F, Swords F. Isolation of salmonid alphavirus subtype 6 from wild-caught ballan wrasse, Labrus bergylta (Ascanius). JOURNAL OF FISH DISEASES 2018; 41:1643-1651. [PMID: 30051469 DOI: 10.1111/jfd.12870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/25/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
The use of cleaner fish as a biological control for sea lice in Atlantic salmon aquaculture has increased in recent years. Wild-caught wrasse are commonly used as cleaner fish in Europe. In Ireland, samples of wrasse from each fishing area are screened for potential pathogens prior to their deployment into sea cages. Salmonid alphavirus was isolated from a pooled sample of ballan wrasse, showing no signs of disease, caught from the NW of Ireland. Partial sequencing of the E2 and nsP3 genes showed that it was closely related to the previously reported SAV subtype 6. This represents only the second isolation of this subtype and the first from a wild fish species, namely ballan wrasse.
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Affiliation(s)
- Neil M Ruane
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | - David Swords
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | | | - Michelle Geary
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | - Cathy Hickey
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | | | | | - Fiona Swords
- Fish Health Unit, Marine Institute, County Galway, Ireland
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16
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Lewisch E, Frank T, Soliman H, Schachner O, Friedl A, El-Matbouli M. First confirmation of salmonid alphavirus infection in Arctic char Salvelinus alpinus and in Austria. DISEASES OF AQUATIC ORGANISMS 2018; 130:71-76. [PMID: 30154274 DOI: 10.3354/dao03265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
To date, sleeping disease (SD) caused by salmonid alphavirus 2 (SAV 2) has been reported in freshwater rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar. This study describes for the first time the occurrence of SD in farm-reared Arctic char Salvelinus alpinus and the occurrence of SAV in Austria. Clinical symptoms were indicative of the disease, and the diagnosis was confirmed by histopathology, infectivity in first passages of CHSE-214 cells and PCR. The phylogenetic analysis of the amplified SAV-nonstructural protein-3 (nsP3) fragment revealed the affiliation to the SAV 2 genotype.
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Affiliation(s)
- E Lewisch
- Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria
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17
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Jarungsriapisit J, Moore LJ, Fiksdal IU, Bjørgen H, Tangerås A, Köllner B, Koppang EO, Patel S. Time after seawater transfer influences immune cell abundance and responses to SAV3 infection in Atlantic salmon. JOURNAL OF FISH DISEASES 2018; 41:1269-1282. [PMID: 29790161 DOI: 10.1111/jfd.12820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/07/2018] [Accepted: 04/08/2018] [Indexed: 06/08/2023]
Abstract
Pancreas disease (PD) caused by salmonid alphavirus (SAV) severely affects salmonid aquaculture during the seawater phase. To characterize immune cells in target tissues for SAV infection, heart, pancreas and pyloric caeca were analysed from two groups of fish adapted to seawater for 2 and 9 weeks. The sections were scored for the relative abundance of cells expressing MHC class II, IgM, CD3, CD8 or neutrophil/granulocyte markers using immuno-histochemical techniques. In general, necrosis of tissue was more severe in fish infected at 2 weeks post-seawater transfer (wpt) compared with those infected at 9 wpt. At 9 wpt, there were higher numbers of MHC II+ cells in heart, pancreas and pyloric caeca, IgM+ cells in heart and pancreas, and CD3+ cells in pancreas compared to those infected at 2 wpt. The majority of the immune cells infiltrating PD-affected tissues were MHC II+ and CD3+ cells suggesting that antigen-presenting cells and T lymphocytes are the main types of immune cells responding to SAV infection. All the investigated cell types were also observed in pyloric caeca of infected fish, suggesting that this tissue may play a role in the immune response to SAV.
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Affiliation(s)
| | - L J Moore
- Institute of Marine Research, Bergen, Norway
| | - I U Fiksdal
- Institute of Marine Research, Bergen, Norway
| | - H Bjørgen
- Section of Anatomy and Pathology, Veterinary Faculty, Institute of Basal Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | | | - B Köllner
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Immunology, Greifswald, Germany
| | - E O Koppang
- Section of Anatomy and Pathology, Veterinary Faculty, Institute of Basal Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - S Patel
- Institute of Marine Research, Bergen, Norway
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18
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Noguera P, Collet B, Klinger M, Örün H, Del Pozo J. Use of Salmon Cardiac Primary Cultures (SCPCs) of different genotypes for comparative kinetics of mx expression, viral load and ultrastructure pathology, after infection with Salmon Pancreas Disease Virus (SPDV). FISH & SHELLFISH IMMUNOLOGY 2018; 72:181-186. [PMID: 29102629 DOI: 10.1016/j.fsi.2017.10.059] [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: 06/27/2017] [Revised: 10/29/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
In vitro fish based models have been extensively applied in human biomedical research but, paradoxically, less frequently in the research of fish health issues. Farmed Atlantic salmon can suffer from several viral conditions affecting the heart. Therefore, species-specific, cardiac in vitro models may represent a useful tool to help further understanding and management of these diseases. The mechanisms underlying genotype based resistance are complex and usually rely on a combined effect of elements from both the innate and adaptive immune response, which are further complicated by external environmental factors. Here we propose that Salmon Cardiac Primary Cultures (SCPCs) are a useful tool to investigate these mechanisms as the basis for genotypic differences between Atlantic salmon families in susceptibility to cardiotropic viral disease. Using SCPCs produced from two different commercially available Atlantic salmon embryonated ova (Atlantic Ova IPN sensitive" (S) and "Atlantic QTL-innOva® IPN/PD" (R)), the influence of host genotype on the viral load and mx expression following Salmon Pancreas Disease Virus infection was assessed over a 15 day period. Both R and S SCPCs groups were successfully infected. A measurable difference between groups of viral nsP1 and host antiviral mx gene expression was observed (i.e. a later, but larger onset of mx expression in the R group). Mx expression peaks were followed by a decrease in viral nsP1 in both groups. Additionally, ultrastructural examination of infected SCPCs allowed the description of degenerative changes at the individual cell level. The SCPC model presents some advantages, over current fish cell culture monolayers and in vivo material, such as the presence of different cell components normally present in the target organ, as well as the removal of a layer of functional complexity (acquired immunity), making it possible to focus on tissue specific, early innate immune mechanisms. These preliminary results highlight the importance of considering genetic origin when selecting the fish source for the production of SCPCs, as well as their usefulness as screening tools for assessment of genotypic differences in disease resistance.
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Affiliation(s)
- Patricia Noguera
- Aquaculture and Marine Environment, Marine Scotland Science, Aberdeen, UK.
| | - Bertrand Collet
- Aquaculture and Marine Environment, Marine Scotland Science, Aberdeen, UK
| | | | - Hristo Örün
- Institut für Anatomie, University Lübeck, Germany
| | - Jorge Del Pozo
- Royal Dick School of Veterinary Sciences, University of Edinburgh, UK
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19
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Chang CJ, Gu J, Robertsen B. Protective effect and antibody response of DNA vaccine against salmonid alphavirus 3 (SAV3) in Atlantic salmon. JOURNAL OF FISH DISEASES 2017; 40:1775-1781. [PMID: 28493514 DOI: 10.1111/jfd.12644] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/10/2017] [Accepted: 03/14/2017] [Indexed: 05/13/2023]
Abstract
This work reports the effect of two DNA vaccines against salmonid alphavirus 3 (SAV3) in Atlantic salmon. Presmolts were vaccinated by intramuscular injection of plasmids encoding the SAV3 structural polyprotein C-E3-E2-6K-E2 (pCSP), E2 only (pE2), or plasmid without insert (pcDNA3.3). E2 is expressed at the surface of cells transfected with pCSP and internally in cells transfected with pE2. A commercial vaccine based on inactivated SAV (NCPD) was used for comparison. At 10 weeks post-vaccination, only fish vaccinated with pCSP showed antibody against E2 and virus-neutralizing activity. Vaccinated fish were infected with SAV3 to determine protection by virus quantitation in serum after 7 days and scoring of pathological changes after 21 days. Fish vaccinated with both pCSP and NCPD vaccines showed significant virus reduction in serum, while fish vaccinated with pE2 did not. All fish vaccinated with pcDNA3.3 and pE2 showed pathological changes in organs typical of PD, 60% of fish vaccinated with NCPD showed PD pathology, while fish vaccinated with pCSP did not show PD pathology. Taken together, DNA vaccination with pCSP provided strong protection for salmon against SAV3 infection, which in part may be due to production of virus-neutralizing antibodies.
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Affiliation(s)
- C J Chang
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - J Gu
- Norwegian Veterinary Institute, Trondheim, Norway
| | - B Robertsen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
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20
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Herath TK, Ashby AJ, Jayasuriya NS, Bron JE, Taylor JF, Adams A, Richards RH, Weidmann M, Ferguson HW, Taggart JB, Migaud H, Fordyce MJ, Thompson KD. Impact of Salmonid alphavirus infection in diploid and triploid Atlantic salmon (Salmo salar L.) fry. PLoS One 2017; 12:e0179192. [PMID: 28949966 PMCID: PMC5614425 DOI: 10.1371/journal.pone.0179192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 05/25/2017] [Indexed: 11/26/2022] Open
Abstract
With increasing interest in the use of triploid salmon in commercial aquaculture, gaining an understanding of how economically important pathogens affect triploid stocks is important. To compare the susceptibility of diploid and triploid Atlantic salmon (Salmo salar L.) to viral pathogens, fry were experimentally infected with Salmonid alphavirus sub-type 1 (SAV1), the aetiological agent of pancreas disease (PD) affecting Atlantic salmon aquaculture in Europe. Three groups of fry were exposed to the virus via different routes of infection: intraperitoneal injection (IP), bath immersion, or cohabitation (co-hab) and untreated fry were used as a control group. Mortalities commenced in the co-hab challenged diploid and triploid fish from 11 days post infection (dpi), and the experiment was terminated at 17 dpi. Both diploid and triploid IP challenged groups had similar levels of cumulative mortality at the end of the experimental period (41.1% and 38.9% respectively), and these were significantly higher (p < 0.01) than for the other challenge routes. A TaqMan-based quantitative PCR was used to assess SAV load in the heart, a main target organ of the virus, and also liver, which does not normally display any pathological changes during clinical infections, but exhibited severe degenerative lesions in the present study. The median viral RNA copy number was higher in diploid fish compared to triploid fish in both the heart and the liver of all three challenged groups. However, a significant statistical difference (p < 0.05) was only apparent in the liver of the co-hab groups. Diploid fry also displayed significantly higher levels of pancreatic and myocardial degeneration than triploids. This study showed that both diploid and triploid fry are susceptible to experimental SAV1 infection. The lower virus load seen in the triploids compared to the diploids may possibly be related to differences in cell metabolism between the two groups, however, further investigation is necessary to confirm this and also to assess the outcome of PD outbreaks in other developmental stages of the fish when maintained in commercial production systems.
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Affiliation(s)
- Tharangani K. Herath
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
- Department of Animal Production, Welfare and Veterinary Sciences, Harper Adams University, Newport, Shropshire, United Kingdom
- * E-mail:
| | - Angela J. Ashby
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
- Fish Vet Group, Inverness, Scotland, United Kingdom
| | | | - James E. Bron
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - John F. Taylor
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Alexandra Adams
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | | | - Manfred Weidmann
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Hugh W. Ferguson
- Marine Medicine Programme, School of Veterinary Medicine, St. George’s University, Grenada, West Indies
| | - John B. Taggart
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Herve Migaud
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | | | - Kim D. Thompson
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
- Moredun Research Institute, Edinburgh, United Kingdom
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21
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Hermanns K, Zirkel F, Kopp A, Marklewitz M, Rwego IB, Estrada A, Gillespie TR, Drosten C, Junglen S. Discovery of a novel alphavirus related to Eilat virus. J Gen Virol 2017; 98:43-49. [PMID: 28206905 DOI: 10.1099/jgv.0.000694] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Most alphaviruses are transmitted by arthropods and infect vertebrate hosts. An exception is Eilat virus (EILV), the only described alphavirus with a host range restricted to insects. We established a new generic reverse transcription PCR assay for alphaviruses and tested 8860 tropical mosquitoes. We detected a novel alphavirus, tentatively named Taï Forest alphavirus (TALV), in Culex decens mosquitoes collected in Ivory Coast. The full genome was sequenced, and closest similarity was found to EILV. Pairwise amino acid identities to EILV ranged between 67 and 88 % for the corresponding proteins, suggesting that TALV defines a proposed new alphavirus species. Phylogenetic analyses placed TALV as a sister species to EILV with a basal relationship to the western equine encephalitis virus complex. In comparison to the highly abundant insect-specific flaviviruses, insect-specific alphaviruses seem to be rare. This new PCR assay can detect novel alphaviruses and may facilitate the identification of additional new alphaviruses.
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Affiliation(s)
- Kyra Hermanns
- Institute of Virology, University of Bonn Medical Centre, Bonn, Germany
| | - Florian Zirkel
- German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.,Institute of Virology, University of Bonn Medical Centre, Bonn, Germany
| | - Anne Kopp
- Institute of Virology, University of Bonn Medical Centre, Bonn, Germany
| | - Marco Marklewitz
- Institute of Virology, University of Bonn Medical Centre, Bonn, Germany
| | - Innocent B Rwego
- College of Natural Sciences, Makerere University, Kampala, Uganda.,Present address: Ecosystem Health Initiative, College of Veterinary Medicine, University of Minnesota, St Paul, MN, USA.,Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.,Department of Environmental Sciences and Program in Population Biology, Ecology and Evolution, Emory University, Atlanta, GA, USA
| | - Alejandro Estrada
- Estación de Biología Tropical Los Tuxtlas, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico
| | - Thomas R Gillespie
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.,Department of Environmental Sciences and Program in Population Biology, Ecology and Evolution, Emory University, Atlanta, GA, USA
| | - Christian Drosten
- German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.,Institute of Virology, University of Bonn Medical Centre, Bonn, Germany
| | - Sandra Junglen
- Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.,German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
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22
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Shi W, Song A, Gao S, Wang Y, Tang L, Xu Y, Ren T, Li Y, Liu M. Rapid and sensitive detection of salmonid alphavirus using TaqMan real-time PCR. Mol Cell Probes 2017; 34:13-20. [PMID: 28433811 DOI: 10.1016/j.mcp.2017.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 04/17/2017] [Accepted: 04/18/2017] [Indexed: 11/29/2022]
Abstract
Salmonid alphavirus (SAV) infection has led to the spread of salmon pancreas disease (PD) and sleeping disease (SD) to salmonids in several countries in Europe, resulting in tremendous economic losses to the fish farming industry. Recently, with increases in the fish import trade, many countries in which SAV has been unreported, such as China, may be seriously threatened by these diseases. It is therefore necessary to develop efficient detection methods for the prevention and diagnosis of SAV infection. In this study, a rapid and sensitive TaqMan real-time PCR method was established and assessed for this purpose. A specificity assay showed no cross-reactions with other common RNA viruses. Regression analysis and standard curves calculated from the Ct values of 10-fold serial dilutions of the standard plasmid showed that the assay was highly reproducible over a wide range of RNA input concentrations. The real-time PCR assay was able to detect SAV at a concentration as low as 1.5 × 101 copies, indicating that it is 107 times more sensitive than the approved conventional RT-PCR method (detection limit, 1.5 × 107 copies) after use on the same samples. Assessment of infected fish samples showed that this assay has a higher sensitivity than the previously reported Q_nsP1 assay. Thus, this TaqMan real-time PCR assay provides a rapid, sensitive, and specific detection method for SAV, offering improved technical support for the clinical diagnosis and epidemiology of SAV.
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Affiliation(s)
- Wen Shi
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Aochen Song
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Shuai Gao
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Yuting Wang
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Lijie Tang
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Yigang Xu
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Tong Ren
- Beijing Entry-exit Inspection and Quarantine Bureau, Beijing 100026, People's Republic of China
| | - Yijing Li
- Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Min Liu
- Northeast Agricultural University, Harbin 150030, People's Republic of China.
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Triploid atlantic salmon (Salmo salar L.) post-smolts accumulate prevalence more slowly than diploid salmon following bath challenge with salmonid alphavirus subtype 3. PLoS One 2017; 12:e0175468. [PMID: 28403165 PMCID: PMC5389816 DOI: 10.1371/journal.pone.0175468] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 03/27/2017] [Indexed: 01/15/2023] Open
Abstract
Triploid Atlantic salmon (Salmo salar L.) may play an important role in the sustainable expansion of the Norwegian aquaculture industry. Therefore, the susceptibility of triploid salmon to common infections such as salmonid alphavirus (SAV), the causative agent of pancreas disease (PD), requires investigation. In this study, shortly after seawater transfer, diploid and triploid post-smolts were exposed to SAV type 3 (SAV3) using a bath challenge model where the infectious dose was 48 TCID50 ml-1 of tank water. Copy number analysis of SAV3 RNA in heart tissue showed that there was no difference in viral loads between the diploids and triploids. Prevalence reached 100% by the end of the 35-day experimental period in both infected groups. However, prevalence accumulated more slowly in the triploid group reaching 19% and 56% at 14 and 21 days post exposure (dpe) respectively. Whereas prevalence in the diploid group was 82% and 100% at the same time points indicating some differences between diploid and triploid fish. Both heart and pancreas from infected groups at 14 dpe showed typical histopathological changes associated with pancreas disease. Observation of this slower accumulation of prevalence following a natural infection route was possible due to the early sampling points and the exposure to a relatively low dose of virus. The triploid salmon in this study were not more susceptible to SAV3 than diploid salmon indicating that they could be used commercially to reduce the environmental impact of escaped farmed fish interbreeding with wild salmon. This is important information regarding the future use of triploid fish in large scale aquaculture where SAV3 is a financial threat to increased production.
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Reid KM, Patel S, Robinson AJ, Bu L, Jarungsriapisit J, Moore LJ, Salinas I. Salmonid alphavirus infection causes skin dysbiosis in Atlantic salmon (Salmo salar L.) post-smolts. PLoS One 2017; 12:e0172856. [PMID: 28264056 PMCID: PMC5338768 DOI: 10.1371/journal.pone.0172856] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/12/2017] [Indexed: 01/08/2023] Open
Abstract
Interactions among host, microbiota and viral pathogens are complex and poorly understood. The goal of the present study is to assess the changes in the skin microbial community of Atlantic salmon (Salmo salar L.) in response to experimental infection with salmonid alphavirus (SAV). The salmon skin microbial community was determined using 16S rDNA pyrosequencing in five different experimental groups: control, 7 days after infection with low-dose SAV, 14 days after infection with low-dose SAV, 7 days after infection with high-dose SAV, and 14 days after infection with high-dose SAV. Both infection treatment and time after infection were strong predictors of the skin microbial community composition. Skin samples from SAV3 infected fish showed an unbalanced microbiota characterized by a decreased abundance of Proteobacteria such as Oleispira sp. and increased abundances of opportunistic taxa including Flavobacteriaceae, Streptococcaceae and Tenacibaculum sp. These results demonstrate that viral infections can result in skin dysbiosis likely rendering the host more susceptible to secondary bacterial infections.
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Affiliation(s)
- Kristin M. Reid
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Sonal Patel
- Institute of Marine Research, Bergen, Norway
| | - Aaron J. Robinson
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Lijing Bu
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | | | | | - Irene Salinas
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
- * E-mail:
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Rimmer AE, Whittington RJ, Tweedie A, Becker JA. Susceptibility of a number of Australian freshwater fishes to dwarf gourami iridovirus (Infectious spleen and kidney necrosis virus). JOURNAL OF FISH DISEASES 2017; 40:293-310. [PMID: 27334576 DOI: 10.1111/jfd.12510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 06/06/2023]
Abstract
Megalocytiviruses cause high mortality diseases that have seriously impacted aquaculture, with the most frequent outbreaks occurring in East and South-East Asia. The international trade of juvenile fish for food and ornamental aquaculture has aided the spread of these viruses, which have spread to Europe and Australia and other regions. Australian freshwater fishes were examined for susceptibility to infection with the exotic megalocytivirus, dwarf gourami iridovirus (DGIV), which belongs to a group with the type species, Infectious spleen and kidney necrosis virus (ISKNV). Fish were held at 23 ± 1 °C and challenged by intraperitoneal (IP) injection or by cohabitation with Murray cod, Maccullochella peelii (Mitchell) infected with DGIV. A species was deemed to be susceptible to DGIV based on evidence of viral replication, as determined by qPCR, and megalocytic inclusion bodies observed histologically. Horizontal transmission occurred between infected Murray cod and golden perch, Macquaria ambigua (Richardson), Macquarie perch, Macquaria australasica (Cuvier) and Murray cod. This indicated that DGIV shed from infected fish held at 23 °C can survive in fresh water and subsequently infect these naïve fish. Further, DGIV administered IP was highly pathogenic to golden perch, Macquarie perch and Murray cod. Compared to these species, the susceptibility of southern pygmy perch, Nannoperca australis (Gunther) was lower. Freshwater catfish (dewfish), Tandanus tandanus (Mitchell), were not susceptible under the experimental conditions based on the absence of clinical disease, mortality and virus replication. This study showed the potential risks associated with naïve and DGIV-infected fish sharing a common water source.
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Affiliation(s)
- A E Rimmer
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - R J Whittington
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - A Tweedie
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - J A Becker
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
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Moore LJ, Jarungsriapisit J, Nilsen TO, Stefansson S, Taranger GL, Secombes CJ, Morton HC, Patel S. Immune gene profiles in Atlantic salmon (salmo salar L.) post-smolts infected with SAV3 by bath-challenge show a delayed response and lower levels of gene transcription compared to injected fish. FISH & SHELLFISH IMMUNOLOGY 2017; 62:320-331. [PMID: 28137651 DOI: 10.1016/j.fsi.2017.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 01/21/2017] [Accepted: 01/23/2017] [Indexed: 06/06/2023]
Abstract
Salmonid alphavirus (SAV) causes pancreatic disease (PD) in salmonids in Northern Europe which results in large economic losses within the aquaculture industry. In order to better understand the underlying immune mechanisms during a SAV3 infection Atlantic salmon post-smolts were infected by either i.m.-injection or bath immersion and their immune responses compared. Analysis of viral loads showed that by 14 dpi i.m.-injected and bath immersion groups had 95.6% and 100% prevalence respectively and that both groups had developed the severe pathology typical of PD. The immune response was evaluated by using RT-qPCR to measure the transcription of innate immune genes involved in the interferon (IFN) response as well as genes associated with inflammation. Our results showed that IFNa transcription was only weakly upregulated, especially in the bath immersion group. Despite this, high levels of the IFN-stimulated genes (ISGs) such as Mx and viperin were observed. The immune response in the i.m.-injected group as measured by immune gene transcription was generally faster, and more pronounced than the response in the bath immersion group, especially at earlier time-points. The response in the bath immersion group started later as expected and appeared to last longer often exceeding the response in the i.m-injected fish at later time-points. High levels of transcription of many genes indicative of an active innate immune response were present in both groups.
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Affiliation(s)
- L J Moore
- Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway
| | - J Jarungsriapisit
- Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway; Department of Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway
| | - T O Nilsen
- Uni Research Environment, Uni Research, Thormøhlensgt, 49B 5006 Bergen, Norway
| | - S Stefansson
- Department of Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway
| | - G L Taranger
- Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway
| | - C J Secombes
- Scottish Fish Immunology Research Centre, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, Scotland, UK
| | - H C Morton
- Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway
| | - S Patel
- Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway.
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27
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Powell MD, Yousaf MN. Cardiovascular Effects of Disease: Parasites and Pathogens. FISH PHYSIOLOGY 2017. [DOI: 10.1016/bs.fp.2017.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Jansen MD, Bang Jensen B, McLoughlin MF, Rodger HD, Taksdal T, Sindre H, Graham DA, Lillehaug A. The epidemiology of pancreas disease in salmonid aquaculture: a summary of the current state of knowledge. JOURNAL OF FISH DISEASES 2017; 40:141-155. [PMID: 27136332 DOI: 10.1111/jfd.12478] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/12/2016] [Accepted: 02/18/2016] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) is a viral disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the disease itself and to factors contributing to agent spread and disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.
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Affiliation(s)
- M D Jansen
- Norwegian Veterinary Institute, Oslo, Norway
| | | | | | - H D Rodger
- Vet-Aqua International, Oranmore, Ireland
| | - T Taksdal
- Norwegian Veterinary Institute, Oslo, Norway
| | - H Sindre
- Norwegian Veterinary Institute, Oslo, Norway
| | - D A Graham
- Animal Health Ireland, Carrick on Shannon, Ireland
| | - A Lillehaug
- Norwegian Veterinary Institute, Oslo, Norway
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29
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Lund M, Røsæg MV, Krasnov A, Timmerhaus G, Nyman IB, Aspehaug V, Rimstad E, Dahle MK. Experimental Piscine orthoreovirus infection mediates protection against pancreas disease in Atlantic salmon (Salmo salar). Vet Res 2016; 47:107. [PMID: 27769313 PMCID: PMC5075195 DOI: 10.1186/s13567-016-0389-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/04/2016] [Indexed: 11/10/2022] Open
Abstract
Viral diseases are among the main challenges in farming of Atlantic salmon (Salmo salar). The most prevalent viral diseases in Norwegian salmon aquaculture are heart and skeletal muscle inflammation (HSMI) caused by Piscine orthoreovirus (PRV), and pancreas disease (PD) caused by Salmonid alphavirus (SAV). Both PRV and SAV target heart and skeletal muscles, but SAV additionally targets exocrine pancreas. PRV and SAV are often present in the same locations and co-infections occur, but the effect of this crosstalk on disease development has not been investigated. In the present experiment, the effect of a primary PRV infection on subsequent SAV infection was studied. Atlantic salmon were infected with PRV by cohabitation, followed by addition of SAV shedder fish 4 or 10 weeks after the initial PRV infection. Histopathological evaluation, monitoring of viral RNA levels and host gene expression analysis were used to assess disease development. Significant reduction of SAV RNA levels and of PD specific histopathological changes were observed in the co-infected groups compared to fish infected by SAV only. A strong correlation was found between histopathological development and expression of disease related genes in heart. In conclusion, experimentally PRV infected salmon are less susceptible to secondary SAV infection and development of PD.
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Affiliation(s)
- Morten Lund
- Section of Immunology, Norwegian Veterinary Institute, Oslo, Norway
| | - Magnus Vikan Røsæg
- SalMar ASA, Kverva, Norway
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Aleksei Krasnov
- Nofima AS, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway
| | - Gerrit Timmerhaus
- Nofima AS, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway
| | - Ingvild Berg Nyman
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | | | - Espen Rimstad
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
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30
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Jarungsriapisit J, Moore LJ, Mæhle S, Skår C, Einen AC, Fiksdal IU, Morton HC, Stefansson SO, Taranger GL, Patel S. Relationship between viral dose and outcome of infection in Atlantic salmon, Salmo salar L., post-smolts bath-challenged with salmonid alphavirus subtype 3. Vet Res 2016; 47:102. [PMID: 27760562 PMCID: PMC5069985 DOI: 10.1186/s13567-016-0385-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/13/2016] [Indexed: 11/10/2022] Open
Abstract
Salmonid alphavirus subtype 3 (SAV3) causes pancreas disease (PD) and adversely affects salmonid aquaculture in Europe. A better understanding of disease transmission is currently needed in order to manage PD outbreaks. Here, we demonstrate the relationship between viral dose and the outcome of SAV3 infection in Atlantic salmon post-smolts using a bath challenge model. Fish were challenged at 12 °C with 3 different SAV3 doses; 139, 27 and 7 TCID50 L−1 of seawater. A dose of as little as 7 TCID50 L−1 of seawater was able to induce SAV3 infection in the challenged population with a substantial level of variation between replicate tanks and, therefore, likely represents a dose close to the minimum dose required to establish an infection in a population. These data also confirm the highly infectious nature of SAV through horizontal transmission. The outcome of SAV3 infection, evaluated by the prevalence of viraemic fish, SAV3-positive hearts, and the virus shedding rate, was positively correlated to the original SAV3 dose. A maximal shedding rate of 2.4 × 104 TCID50 L−1 of seawater h−1 kg−1 was recorded 10 days post-exposure (dpe) from the highest dose group. The method reported here, for the quantification of infectious SAV3 in seawater, could be useful to monitor PD status or obtain data from SAV3 outbreaks at field locations. This information could be incorporated into pathogen dispersal models to improve risk assessment and to better understand how SAV3 spreads between farms during outbreaks. This information may also provide new insights into the control and mitigation of PD.
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Affiliation(s)
- Jiraporn Jarungsriapisit
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.,Department of Biology, University of Bergen, P. O. Box 7803, 5020, Bergen, Norway
| | - Lindsey J Moore
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - Stig Mæhle
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - Cecilie Skår
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | | | | | | | - Sigurd O Stefansson
- Department of Biology, University of Bergen, P. O. Box 7803, 5020, Bergen, Norway
| | | | - Sonal Patel
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
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31
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Chang CJ, Jenssen I, Robertsen B. Protection of Atlantic salmon against salmonid alphavirus infection by type I interferons IFNa, IFNb and IFNc. FISH & SHELLFISH IMMUNOLOGY 2016; 57:35-40. [PMID: 27530458 DOI: 10.1016/j.fsi.2016.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 06/06/2023]
Abstract
Salmonid alphavirus 3 (SAV3) causes pancreas disease (PD), which is a major problem in Norwegian aquaculture of Atlantic salmon. In this work we studied antiviral activities of salmon type I interferons IFNa, IFNb and IFNc against SAV3 infection in cell culture and in live fish to increase the understanding of the innate immunity of salmon against this virus. Recombinant IFNa, IFNb and IFNc all induced antiviral activity against SAV3 in ASK cells. For in vivo studies, we injected salmon presmolts intramuscularly with plasmids encoding salmon IFNa, IFNb and IFNc or a control plasmid and measured expression of the antiviral protein Mx in pancreas after 2 and 10 weeks and protection against SAV3 infection after 10 weeks. IFNb and IFNc plasmids, but not IFNa plasmid induced Mx expression in pancreas as shown by RT-qPCR and immunohistochemistry. A high level of protection against SAV3 infection by IFNc plasmid was observed by a strong reduction of virus load in serum and by a marked reduction in pathology of pancreas and heart compared to control fish. Lesser but significant protection was observed with IFNb plasmid while no protection was observed after treatment with IFNa plasmid. Taken together, this work suggests that IFNa provides protection of salmon against SAV3 locally in an infected area while IFNb and IFNc provides systemic protection against the virus.
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Affiliation(s)
- Chia-Jung Chang
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Iris Jenssen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Børre Robertsen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, 9037 Tromsø, Norway.
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32
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Pettersen J, Brynildsrud O, Huseby R, Rich K, Aunsmo A, Bang BJ, Aldrin M. The epidemiological and economic effects from systematic depopulation of Norwegian marine salmon farms infected with pancreas disease virus. Prev Vet Med 2016; 132:113-124. [DOI: 10.1016/j.prevetmed.2016.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/31/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
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Skjold P, Sommerset I, Frost P, Villoing S. Vaccination against pancreas disease in Atlantic salmon, Salmo salar L., reduces shedding of salmonid alphavirus. Vet Res 2016; 47:78. [PMID: 27496170 PMCID: PMC4975881 DOI: 10.1186/s13567-016-0362-9] [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: 01/18/2016] [Accepted: 06/09/2016] [Indexed: 11/28/2022] Open
Abstract
Salmon pancreas disease virus, often referred to as salmonid alphavirus (SAV), causes pancreas disease (PD) in European salmonids. SAV transmits horizontally from fish shedding virus into the water and ocean currents are believed to be a main contributor of viral spread between marine farms. Vaccination against PD is previously shown to reduce mortality and severity of clinical PD. In this study, we demonstrate that vaccination against PD significantly reduces viral shedding from infected individuals. The results suggest that PD vaccination can be an important tool to reduce the infection pressure, a known key risk for PD outbreaks at neighbouring farms.
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Affiliation(s)
- Pål Skjold
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway.
| | - Ingunn Sommerset
- MSD Animal Health Norge AS, Thormøhlensgate 55, 5008, Bergen, Norway
| | - Petter Frost
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway
| | - Stephane Villoing
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway
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Jarungsriapisit J, Moore LJ, Taranger GL, Nilsen TO, Morton HC, Fiksdal IU, Stefansson S, Fjelldal PG, Evensen Ø, Patel S. Atlantic salmon (Salmo salar L.) post-smolts challenged two or nine weeks after seawater-transfer show differences in their susceptibility to salmonid alphavirus subtype 3 (SAV3). Virol J 2016; 13:66. [PMID: 27068518 PMCID: PMC4827186 DOI: 10.1186/s12985-016-0520-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/31/2016] [Indexed: 11/14/2022] Open
Abstract
Background Pancreas disease (PD), caused by salmonid alphavirus (SAV), is an important disease affecting salmonid aquaculture. It has been speculated that Atlantic salmon post-smolts are more prone to infections in the first few weeks following seawater- transfer. After this period of seawater acclimatization, the post-smolts are more robust and better able to resist infection by pathogens. Here we describe how we established a bath immersion (BI) model for SAV subtype 3 (SAV3) in seawater. We also report how this challenge model was used to study the susceptibility of post-smolts to SAV3 infection in two groups of post-smolts two weeks or nine weeks after seawater - transfer. Methods Post-smolts, two weeks (Phase-A) or nine weeks (Phase-B) after seawater- transfer, were infected with SAV3 by BI or intramuscular injection (IM) to evaluate their susceptibility to infection. A RT-qPCR assay targeting the non-structural protein (nsP1) gene was performed to detect SAV3-RNA in blood, heart tissue and electropositive-filtered tank-water. Histopathological changes were examined by light microscope, and the presence of SAV3 antigen in pancreas tissue was confirmed using immuno-histochemistry. Results Virus shedding from the Phase-B fish injected with SAV3 (IM Phase-B) was markedly lower than that from IM Phase-A fish. A lower percentage of viraemia in Phase-B fish compared with Phase-A fish was also observed. Viral RNA in hearts from IM Phase-A fish was higher than in IM Phase-B fish at all sampling points (p < 0.05) and a similar trend was also seen in the BI groups. Necrosis of exocrine pancreatic cells was observed in all infected groups. Extensive histopathological changes were found in Phase-A fish whereas milder PD-related histopathological lesions were seen in Phase-B fish. The presence of SAV3 in pancreas tissue from all infected groups was also confirmed by immuno-histochemical staining. Conclusion Our results suggest that post-smolts are more susceptible to SAV3 infection two weeks after seawater-transfer than nine weeks after transfer. In addition, the BI challenge model described here offers an alternative SAV3 infection model when better control of the time-of-infection is essential for studying basic immunological mechanisms and disease progression. Electronic supplementary material The online version of this article (doi:10.1186/s12985-016-0520-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- J Jarungsriapisit
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.,Department of Biology, University of Bergen, P.O. Box 7803, N-5020, Bergen, Norway
| | - L J Moore
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - G L Taranger
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - T O Nilsen
- Uni Research Environment, Uni Research, Thormøhlensgt., 49 B, 5006, Bergen, Norway
| | - H C Morton
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - I U Fiksdal
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway
| | - S Stefansson
- Department of Biology, University of Bergen, P.O. Box 7803, N-5020, Bergen, Norway
| | - P G Fjelldal
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Ø Evensen
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences, P.O. Box 8146 Dep, N-0033, Oslo, Norway
| | - S Patel
- Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
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35
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Herath TK, Ferguson HW, Weidmann MW, Bron JE, Thompson KD, Adams A, Muir KF, Richards RH. Pathogenesis of experimental salmonid alphavirus infection in vivo: an ultrastructural insight. Vet Res 2016; 47:7. [PMID: 26743442 PMCID: PMC4705579 DOI: 10.1186/s13567-015-0300-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 05/23/2015] [Indexed: 12/27/2022] Open
Abstract
Salmonid alphavirus (SAV) is an enveloped, single-stranded,
positive sense RNA virus belonging to the family Togaviridae. It causes economically devastating disease in cultured salmonids. The characteristic features of SAV infection include severe histopathological changes in the heart, pancreas and skeletal muscles of diseased fish. Although the presence of virus has been reported in a wider range of tissues, the mechanisms responsible for viral tissue tropism and for lesion development during the disease are not clearly described or understood. Previously, we have described membrane-dependent morphogenesis of SAV and associated apoptosis-mediated cell death in vitro. The aims of the present study were to explore ultrastructural changes associated with SAV infection in vivo. Cytolytic changes were observed in heart, but not in gill and head-kidney of virus-infected fish, although they still exhibited signs of SAV morphogenesis. Ultrastructural changes associated with virus replication were also noted in leukocytes in the head kidney of virus-infected fish. These results further describe the presence of degenerative lesions in the heart as expected, but not in the gills and in the kidney.
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Affiliation(s)
- Tharangani K Herath
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
| | - Hugh W Ferguson
- School of Veterinary Medicine, St George's University, St. George, Grenada, West Indies.
| | - Manfred W Weidmann
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
| | - James E Bron
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
| | - Kimberly D Thompson
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK. .,Moredun Research Institute, Pentlands Science Park, Bush Loan Penicuik, Edinburgh, UK.
| | - Alexandra Adams
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
| | - Katherine F Muir
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
| | - Randolph H Richards
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, UK.
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36
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Taksdal T, Jensen BB, Böckerman I, McLoughlin MF, Hjortaas MJ, Ramstad A, Sindre H. Mortality and weight loss of Atlantic salmon, Salmon salar L., experimentally infected with salmonid alphavirus subtype 2 and subtype 3 isolates from Norway. JOURNAL OF FISH DISEASES 2015; 38:1047-61. [PMID: 25322679 DOI: 10.1111/jfd.12312] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/20/2014] [Accepted: 08/20/2014] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) caused by salmonid alphavirus (SAV) has a significant negative economic impact in the salmonid fish farming industry in northern Europe. Until recently, only SAV subtype 3 was present in Norwegian fish farms. However, in 2011, a marine SAV 2 subtype was detected in a fish farm outside the PD-endemic zone. This subtype has spread rapidly among fish farms in mid-Norway. The PD mortality in several farms has been lower than expected, although high mortality has also been reported. In this situation, the industry and the authorities needed scientific-based information about the virulence of the marine SAV 2 strain in Norway to decide how to handle this new situation. Atlantic salmon post-smolts were experimentally infected with SAV 2 and SAV 3 strains from six different PD cases in Norway. SAV 3-infected fish showed higher mortality than SAV 2-infected fish. Among the SAV 3 isolates, two isolates gave higher mortality than the third one. At the end of the experiment, fish in all SAV-infected groups had significantly lower weight than the uninfected control fish. This is the first published paper on PD to document that waterborne infection produced significantly higher mortality than intraperitoneal injection.
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Affiliation(s)
- T Taksdal
- Norwegian Veterinary Institute, Oslo, Norway
| | | | - I Böckerman
- Norwegian Veterinary Institute, Oslo, Norway
| | | | | | | | - H Sindre
- Norwegian Veterinary Institute, Oslo, Norway
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37
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Johansen LH, Thim HL, Jørgensen SM, Afanasyev S, Strandskog G, Taksdal T, Fremmerlid K, McLoughlin M, Jørgensen JB, Krasnov A. Comparison of transcriptomic responses to pancreas disease (PD) and heart and skeletal muscle inflammation (HSMI) in heart of Atlantic salmon (Salmo salar L). FISH & SHELLFISH IMMUNOLOGY 2015; 46:612-23. [PMID: 26232631 DOI: 10.1016/j.fsi.2015.07.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 06/12/2015] [Accepted: 07/27/2015] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) and heart and skeletal muscle inflammation (HSMI) are viral diseases associated with SAV (salmonid alphavirus) and PRV (piscine reovirus), which induce systemic infections and pathologies in cardiac and skeletal muscle tissue of farmed Atlantic salmon (Salmo salar L), resulting in severe morbidity and mortality. While general features of the clinical symptoms and pathogenesis of salmonid viral diseases are relatively well studied, much less is known about molecular mechanisms associated with immunity and disease-specific changes. In this study, transcriptomic analyses of heart tissue from PD and HSMI challenged Atlantic salmon were done, focusing on the mature phases of both diseases at respectively 28-35 and 42-77 days post infection. A large number of immune genes was activated in both trials with prevalence of genes associated with early innate antiviral responses, their expression levels being slightly higher in PD challenged fish. Activation of the IFN axis was in parallel with inflammatory changes that involved diverse humoral and cellular factors. Adaptive immune response genes were more pronounced in fish with HSMI, as suggested by increased expression of a large number of genes associated with differentiation and maturation of B lymphocytes and cytotoxic T cells. A similar down-regulation of non-immune genes such as myofiber and mitochondrial proteins between diseases was most likely reflecting myocardial pathology. A suite of genes important for cardiac function including B-type natriuretic peptide and four neuropeptides displayed differential expression between PD and HSMI. Comparison of results revealed common and distinct features and added to the understanding of both diseases at their mature phases with typical clinical pictures. A number of genes that showed disease-specific changes can be of interest for diagnostics.
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Affiliation(s)
| | - Hanna L Thim
- Norwegian College of Fisheries Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
| | | | - Sergey Afanasyev
- Nofima AS, P.O. Box 6122, N-9291 Tromsø, Norway; Sechenov Institute of Evolutionary Physiology and Biochemistry, M. Toreza Av. 44, Saint Petersburg 194223, Russia
| | - Guro Strandskog
- Norwegian College of Fisheries Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Torunn Taksdal
- Norwegian Veterinary Institute, P.O. Box 750, N-0106 Oslo, Norway
| | - Kjersti Fremmerlid
- Norwegian College of Fisheries Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
| | | | - Jorunn B Jørgensen
- Norwegian College of Fisheries Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
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38
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Pettersen J, Rich K, Jensen B, Aunsmo A. The economic benefits of disease triggered early harvest: A case study of pancreas disease in farmed Atlantic salmon from Norway. Prev Vet Med 2015; 121:314-24. [DOI: 10.1016/j.prevetmed.2015.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 10/23/2022]
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39
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Jansen MD, Jensen BB, Brun E. Clinical manifestations of pancreas disease outbreaks in Norwegian marine salmon farming - variations due to salmonid alphavirus subtype. JOURNAL OF FISH DISEASES 2015; 38:343-53. [PMID: 24661057 DOI: 10.1111/jfd.12238] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/20/2014] [Accepted: 01/23/2014] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) in Norwegian salmonid aquaculture has traditionally been caused by salmonid alphavirus (SAV) subtype 3. Following the isolation of a novel SAV subtype in 2010, marine SAV2, two separate endemic areas have developed. It has been debated whether disease outbreaks due to marine SAV2 result in milder clinical manifestations compared to outbreaks caused by SAV3. The aim of this study was to descriptively investigate site-level differences in the clinical manifestations of marine SAV2 and SAV3 at Norwegian seawater sites diagnosed with PD in 2012. The findings suggest that Norwegian PD outbreaks caused by marine SAV2 result in lower mortality and milder clinical signs compared to outbreaks caused by SAV3. For sites without reported PD-related mortality, there was no difference in the mortality levels between sites infected by marine SAV2 and SAV3. The results also indicate that there are no differences in grading quality at slaughter between the SAV subtypes.
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Affiliation(s)
- M D Jansen
- Section for Epidemiology, Norwegian Veterinary Institute, Oslo, Norway
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40
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Cano I, Joiner C, Bayley A, Rimmer G, Bateman K, Feist SW, Stone D, Paley R. An experimental means of transmitting pancreas disease in Atlantic salmon Salmo salar L. fry in freshwater. JOURNAL OF FISH DISEASES 2015; 38:271-281. [PMID: 25297529 DOI: 10.1111/jfd.12310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 06/04/2023]
Abstract
A challenge model for pancreas disease in Atlantic salmon, Salmo salar L. fry, was developed comparing two salmonid alphavirus (SAV) subtypes: SAV1 and SAV5. Viral doses of 3 × 10(5) TCID50 mL(-1) for SAV1 and 3 × 10(4) for SAV5 were tested in triplicate tanks, each containing 450 salmon fry. Cumulative mortalities of 1.2% were recorded. Titres of virus recovered from the mortalities ranged from 10(2) to 10(7) TCID50 mL(-1) . Fry were sampled at 3, 5 and 7.5 weeks post-challenge. Sampling after 3 weeks revealed a high prevalence of infection in the absence of clinical signs, and infectious virus was recovered from 80% and 43% of sampled fry infected with SAV1 and SAV5, respectively. After 5 weeks pancreas, heart and red skeletal muscle lesions were generally observed, whilst degeneration in white skeletal muscle was observed only in fish infected with SAV1. In situ hybridisation confirmed the presence of viral genome in infected pancreas, heart and muscle. After 7.5 weeks, infectious virus (both isolates) was recovered from 13.3% of the fish sampled, with a viral titre of 10(2) TCID50 mL(-1) . Clearly, salmon fry are susceptible to SAV infection and pancreas disease.
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Affiliation(s)
- I Cano
- Aquatic Animal Disease, Centre for Environment, Fisheries and Aquaculture Science, The Nothe Weymouth, Dorset, UK
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41
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Hall L, Munro L, Wallace I, McIntosh R, MacNeish K, Murray A. An approach to evaluating the reliability of diagnostic tests on pooled groups of infected individuals. Prev Vet Med 2014; 116:305-12. [DOI: 10.1016/j.prevetmed.2014.01.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 10/23/2013] [Accepted: 01/21/2014] [Indexed: 11/30/2022]
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42
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Stene A, Bang Jensen B, Knutsen Ø, Olsen A, Viljugrein H. Seasonal increase in sea temperature triggers pancreas disease outbreaks in Norwegian salmon farms. JOURNAL OF FISH DISEASES 2014; 37:739-751. [PMID: 23980568 DOI: 10.1111/jfd.12165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/10/2013] [Accepted: 07/10/2013] [Indexed: 06/02/2023]
Abstract
Pancreas disease (PD) is a viral disease causing negative impacts on economy of salmon farms and fish welfare. Its transmission route is horizontal, and water transport by ocean currents is an important factor for transmission. In this study, the effect of temperature changes on PD dynamics in the field has been analysed for the first time. To identify the potential time of exposure to the virus causing PD, a hydrodynamic current model was used. A cohort of salmon was assumed to be infected the month it was exposed to virus from other infective cohorts by estimated water contact. The number of months from exposure to outbreak defined the incubation period, which was used in this investigation to explore the relationship between temperature changes and PD dynamics. The time of outbreak was identified by peak in mortality based on monthly records from active sites. Survival analysis demonstrated that cohorts exposed to virus at decreasing sea temperature had a significantly longer incubation period than cohorts infected when the sea temperature was increasing. Hydrodynamic models can provide information on the risk of being exposed to pathogens from neighbouring farms. With the knowledge of temperature-dependent outbreak probability, the farmers can emphasize prophylactic management, avoid stressful operations until the sea temperature is decreasing and consider removal of cohorts at risk, if possible.
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Affiliation(s)
- A Stene
- Ålesund University College, Ålesund, Norway
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43
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Graham DA, Rowley HR, Frost P. Cross-neutralization studies with salmonid alphavirus subtype 1-6 strains: results with sera from experimental studies and natural infections. JOURNAL OF FISH DISEASES 2014; 37:683-91. [PMID: 23957811 DOI: 10.1111/jfd.12167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 05/13/2023]
Abstract
The serological reactivity between strains of each of the six currently genetically defined subtypes of salmonid alphavirus (SAV) was examined by comparison of homologous and heterologous virus neutralization titres on sera from experimentally infected fish. With the exception of the level of SAV subtype 6 neutralization by heterologous sera, good cross-neutralization was detected between all subtypes, albeit with variation in geometric mean titres when each subtype-specific serum set was tested against the panel of virus subtypes. A similar pattern was evident with field sera, except that heterologous neutralization of the SAV6 strain was more evident. In only 23% of available pairwise comparisons was the homologous titre recorded with an experimentally derived serum fourfold or greater than the heterologous titre, and in only two instances was this difference demonstrated in both directions. No virus strains consistently met the old serology-based criteria (Sub-committee on Inter-relationships Among Catalogued Alphaviruses) to be considered separate subtypes within an alphavirus species. Only when testing with an SAV subtype-2-specific monoclonal antibody was a major difference between homologous and heterologous neutralization capacity evident. These results provide new direct or indirect information in terms of SAV classification, vaccine efficacy and the selection and validation of reagents for serological and immunological diagnostic purposes.
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Affiliation(s)
- D A Graham
- Fish Diseases Unit, Agrifood and Biosciences Institute, Stormont, UK
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44
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McCleary S, Giltrap M, Henshilwood K, Ruane NM. Detection of salmonid alphavirus RNA in Celtic and Irish Sea flatfish. DISEASES OF AQUATIC ORGANISMS 2014; 109:1-7. [PMID: 24781791 DOI: 10.3354/dao02719] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Pancreas disease (PD) caused by the salmonid alphavirus (SAV) has been the most significant cause of mortalities in Irish farmed salmon Salmo salar L. over the past decade. SAV is a single-strand positive-sense RNA virus, originally thought to be unique to salmonids, but has recently been detected using real-time RT-PCR in a number of wild non-salmonid fish. In the present report, 610 wild flatfish (common dab Limanda limanda, plaice Pleuronectes platessa and megrim Lepidorhombus whiffiagonis) were caught from the Irish and Celtic Seas and screened for SAV using real-time RT-PCR and sequencing. In general, a very low prevalence was recorded in common dab and plaice, except for 1 haul in Dublin Bay where 25% of common dab were SAV-positive. SAV sequence analysis supported the fact that real-time RT-PCR detections were specific and further characterised the detected viruses within SAV Subtype I, the predominant subtype found in farmed salmon in Ireland.
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Affiliation(s)
- S McCleary
- Marine Institute, Rinville, Oranmore, Galway, Ireland
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45
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Vaccine Adjuvants in Fish Vaccines Make a Difference: Comparing Three Adjuvants (Montanide ISA763A Oil, CpG/Poly I:C Combo and VHSV Glycoprotein) Alone or in Combination Formulated with an Inactivated Whole Salmonid Alphavirus Antigen. Vaccines (Basel) 2014; 2:228-51. [PMID: 26344619 PMCID: PMC4494258 DOI: 10.3390/vaccines2020228] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/21/2014] [Accepted: 03/13/2014] [Indexed: 01/01/2023] Open
Abstract
Most commercial vaccines offered to the aquaculture industry include inactivated antigens (Ag) formulated in oil adjuvants. Safety concerns are related to the use of oil adjuvants in multivalent vaccines for fish, since adverse side effects (e.g., adhesions) can appear. Therefore, there is a request for vaccine formulations for which protection will be maintained or improved, while the risk of side effects is reduced. Here, by using an inactivated salmonid alphavirus (SAV) as the test Ag, the combined use of two Toll-like receptor (TLR) ligand adjuvants, CpG oligonucleotides (ODNs) and poly I:C, as well as a genetic adjuvant consisting of a DNA plasmid vector expressing the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) was explored. VHSV-G DNA vaccine was intramuscularly injected in combination with intraperitoneal injection of either SAV Ag alone or combined with the oil adjuvant, Montanide ISA763, or the CpG/polyI:C combo. Adjuvant formulations were evaluated for their ability to boost immune responses and induce protection against SAV in Atlantic salmon, following cohabitation challenge. It was observed that CpG/polyI:C-based formulations generated the highest neutralizing antibody titres (nAbs) before challenge, which endured post challenge. nAb responses for VHSV G-DNA- and oil-adjuvanted formulations were marginal compared to the CpG/poly I:C treatment. Interestingly, heat-inactivated sera showed reduced nAb titres compared to their non-heated counterparts, which suggests a role of complement-mediated neutralization against SAV. Consistently elevated levels of innate antiviral immune genes in the CpG/polyI:C injected groups suggested a role of IFN-mediated responses. Co-delivery of the VHSV-G DNA construct with either CpG/polyI:C or oil-adjuvanted SAV vaccine generated higher CD4 responses in head kidney at 48 h compared to injection of this vector or SAV Ag alone. The results demonstrate that a combination of pattern recognizing receptor (PRR) ligands, such as CpG/polyI:C, increases both adaptive and innate responses and represents a promising adjuvant strategy for enhancing the protection of future viral vaccines.
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46
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Stene A, Viljugrein H, Yndestad H, Tavornpanich S, Skjerve E. Transmission dynamics of pancreas disease (PD) in a Norwegian fjord: aspects of water transport, contact networks and infection pressure among salmon farms. JOURNAL OF FISH DISEASES 2014; 37:123-134. [PMID: 23452114 DOI: 10.1111/jfd.12090] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 06/01/2023]
Abstract
Pancreas disease (PD) in marine salmon farming is caused by salmon pancreas disease virus (SPDV). Virus survival, infection pressure and contact networks among farms influence the potential of PD to spread. The present study aims to explore contact networks and infection pressure and their ability to explain transmission dynamics of PD in a Norwegian fjord. In this study, we included all records of PD by subtype 3 (SPDV3) in the study population from the first reported in August 2006 to the last reported in November 2009. Using logistic regression analyses, we found that contact network by water transport explained better transmission of PD than contact networks defined by ownership or close distance to infected farms. Hydrodynamic modelling can be a valuable tool to forecast the spread of PD and thereby take actions to reduce the transmission. Knowing the risk of getting infected, it is important to avoid water transport from infected farms when new cohorts are transferred to sea water, and to have conscious control regarding management operations between farms.
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Affiliation(s)
- A Stene
- Aalesund University College, Ålesund, Norway
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47
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Hikke MC, Verest M, Vlak JM, Pijlman GP. Salmonid alphavirus replication in mosquito cells: towards a novel vaccine production system. Microb Biotechnol 2014; 7:480-4. [PMID: 24418177 PMCID: PMC4229328 DOI: 10.1111/1751-7915.12100] [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: 07/23/2013] [Revised: 10/14/2013] [Accepted: 10/21/2013] [Indexed: 11/28/2022] Open
Abstract
Salmonid alphavirus (SAV) causes pancreas disease and sleeping disease in Atlantic salmon (Salmosalar) and rainbow trout (Oncorhynchus mykiss) and confers a major burden to the aquaculture industry. A commercial inactivated whole virus vaccine propagated in a salmon cell line at low temperature provides effective protection against SAV infections. Alphaviruses (family Togaviridae) are generally transmitted between vertebrate hosts via blood-sucking arthropod vectors, typically mosquitoes. SAV is unique in this respect because it can be transmitted directly from fish to fish and has no known invertebrate vector. Here, we show for the first time that SAV is able to complete a full infectious cycle within arthropod cells derived from the Asian tiger mosquito Aedes albopictus. Progeny virus is produced in C6/36 and U4.4. cells in a temperature-dependent manner (at 15°C but not at 18°C), can be serially passaged and remains infectious to salmonid Chinook salmon embryo cells. This suggests that SAV is not a vertebrate-restricted alphavirus after all and may have the potential to replicate in invertebrates. The current study also shows the ability of SAV to be propagated in mosquito cells, thereby possibly providing an alternative SAV production system for vaccine applications.
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Affiliation(s)
- Mia C Hikke
- Wageningen University, Laboratory of Virology, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
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48
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Braceland M, Bickerdike R, Tinsley J, Cockerill D, Mcloughlin M, Graham D, Burchmore R, Weir W, Wallace C, Eckersall P. The serum proteome of Atlantic salmon, Salmo salar, during pancreas disease (PD) following infection with salmonid alphavirus subtype 3 (SAV3). J Proteomics 2013; 94:423-36. [PMID: 24145143 PMCID: PMC3878379 DOI: 10.1016/j.jprot.2013.10.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/27/2013] [Accepted: 10/11/2013] [Indexed: 02/07/2023]
Abstract
Salmonid alphavirus is the aetological agent of pancreas disease (PD) in marine Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, with most outbreaks in Norway caused by SAV subtype 3 (SAV3). This atypical alphavirus is transmitted horizontally causing a significant economic impact on the aquaculture industry. This histopathological and proteomic study, using an established cohabitational experimental model, investigated the correlation between tissue damage during PD and a number of serum proteins associated with these pathologies in Atlantic salmon. The proteins were identified by two-dimensional electrophoresis, trypsin digest and peptide MS/MS fingerprinting. A number of humoral components of immunity which may act as biomarkers of the disease were also identified. For example, creatine kinase, enolase and malate dehydrogenase serum concentrations were shown to correlate with pathology during PD. In contrast, hemopexin, transferrin, and apolipoprotein, amongst others, altered during later stages of the disease and did not correlate with tissue pathologies. This approach has given new insight into not only PD but also fish disease as a whole, by characterisation of the protein response to infection, through pathological processes to tissue recovery. BIOLOGICAL SIGNIFICANCE Salmonid alphavirus causes pancreas disease (PD) in Atlantic salmon, Salmo salar, and has a major economic impact on the aquaculture industry. A proteomic investigation of the change to the serum proteome during PD has been made with an established experimental model of the disease. Serum proteins were identified by two-dimensional electrophoresis, trypsin digest and peptide MS/MS fingerprinting with 72 protein spots being shown to alter significantly over the 12week period of the infection. The concentrations of certain proteins in serum such as creatine kinase, enolase and malate dehydrogenase were shown to correlate with tissue pathology while other proteins such as hemopexin, transferrin, and apolipoprotein, altered in concentration during later stages of the disease and did not correlate with tissue pathologies. The protein response to infection may be used to monitor disease progression and enhance understanding of the pathology of PD.
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Affiliation(s)
- M. Braceland
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Bearsden Rd, Glasgow, G61 1QH, Scotland, UK
| | - R. Bickerdike
- BioMar Ltd., North Shore Road, Grangemouth Docks, Grangemouth, FK3 8UL, Scotland, UK
| | - J. Tinsley
- BioMar Ltd., North Shore Road, Grangemouth Docks, Grangemouth, FK3 8UL, Scotland, UK
| | - D. Cockerill
- Marine Harvest Scotland, Farms Office Blar Mhor Industrial Estate, Fort William, PH33 7PT, Scotland, UK
| | - M.F. Mcloughlin
- Aquatic Vet Services, 35 Cherryvalley Pk, Belfast, BT5 6PN, Northern Ireland, UK
| | - D.A. Graham
- Fish Diseases Unit, Agri-food and Biosciences Institute, Stoney Rd, Stormont, Belfast, BT4 3SD, Northern Ireland, UK
| | - R.J. Burchmore
- Institute of Infection, Immunity & Inflammation, University of Glasgow, Bearsden Rd Glasgow, G61 1QH, Scotland, UK
| | - W. Weir
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Bearsden Rd, Glasgow, G61 1QH, Scotland, UK
| | - C. Wallace
- VESO Vikan, Aquamedical Contract Research, Vikan, N-7800 Namsos, Norway
| | - P.D. Eckersall
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Bearsden Rd, Glasgow, G61 1QH, Scotland, UK
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49
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Olsen CM, Pemula AK, Braaen S, Sankaran K, Rimstad E. Salmonid alphavirus replicon is functional in fish, mammalian and insect cells and in vivo in shrimps (Litopenaeus vannamei). Vaccine 2013; 31:5672-9. [DOI: 10.1016/j.vaccine.2013.09.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/18/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
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50
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Herath TK, Thompson KD, Adams A, Richards RH. Interferon-mediated host response in experimentally induced salmonid alphavirus 1 infection in Atlantic salmon (Salmo salar L.). Vet Immunol Immunopathol 2013; 155:9-20. [DOI: 10.1016/j.vetimm.2013.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 05/13/2013] [Accepted: 05/17/2013] [Indexed: 12/01/2022]
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