1
|
Madhun AS, Karlsbakk E, Skaala Ø, Solberg MF, Wennevik V, Harvey A, Meier S, Fjeldheim PT, Andersen KC, Glover KA. Most of the escaped farmed salmon entering a river during a 5-year period were infected with one or more viruses. JOURNAL OF FISH DISEASES 2024; 47:e13950. [PMID: 38555528 DOI: 10.1111/jfd.13950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/01/2024] [Accepted: 03/14/2024] [Indexed: 04/02/2024]
Abstract
Disease interactions between farmed and wild populations have been poorly documented for most aquaculture species, in part due to the complexities to study this. Here, we tested 567 farmed Atlantic salmon escapees, captured in a Norwegian river during 2014-2018, for five viral infections that are prevalent in global salmonid aquaculture. Over 90% of the escapees were infected with one or more viruses. Overall prevalences were: 75.7% for piscine orthoreovirus (PRV-1), 43.6% for salmonid alphavirus (SAV), 31.2% for piscine myocarditis virus (PMCV), 1.2% for infectious pancreatic necrosis virus (IPNV) and 0.4% for salmon anaemia virus (ISAV). A significantly higher prevalence of PMCV infection was observed in immature compared to mature individuals. The prevalence of both SAV and PMCV infections was higher in fish determined by fatty acid profiling to be 'recent' as opposed to 'early' escapees that had been in the wild for a longer period of time. This is the first study to establish a time-series of viral infection status of escapees entering a river with a native salmon population. Our results demonstrate that farmed escapees represent a continuous source of infectious agents which could potentially be transmitted to wild fish populations.
Collapse
Affiliation(s)
| | - Egil Karlsbakk
- Institute of Marine Research, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Thorarinsson R, Ramstad A, Wolf JC, Sindre H, Skjerve E, Rimstad E, Evensen Ø, Rodriguez JF. Effect of pancreas disease vaccines on infection levels and virus transmission in Atlantic salmon ( Salmo salar) challenged with salmonid alphavirus, genotype 2. Front Immunol 2024; 15:1342816. [PMID: 38515753 PMCID: PMC10955579 DOI: 10.3389/fimmu.2024.1342816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/21/2024] [Indexed: 03/23/2024] Open
Abstract
Salmonid alphavirus (SAV) causes pancreas disease (PD), which negatively impacts farmed Atlantic salmon. In this study, fish were vaccinated with a DNA-PD vaccine (DNA-PD) and an oil-adjuvanted, inactivated whole virus PD vaccine (Oil-PD). Controls were two non-PD vaccinated groups. Fish were kept in one tank and challenged by cohabitation with SAV genotype 2 in seawater. Protection against infection and mortality was assessed for 84 days (Efficacy study). Nineteen days post challenge (dpc), subgroups of fish from all treatment groups were transferred to separate tanks and cohabited with naïve fish (Transmission study 1) or fish vaccinated with a homologous vaccine (Transmission study 2), to evaluate virus transmission for 26 days (47 dpc). Viremia, heart RT-qPCR and histopathological scoring of key organs affected by PD were used to measure infection levels. RT-droplet digital PCR quantified shedding of SAV into water for transmission studies. The Efficacy study showed that PD associated growth-loss was significantly lower and clearance of SAV2 RNA significantly higher in the PD-DNA group compared to the other groups. The PD-DNA group had milder lesions in the heart and muscle. Cumulative mortality post challenge was low and not different between groups, but the DNA-PD group had delayed time-to-death. In Transmission study 1, the lowest water levels of SAV RNA were measured in the tanks containing the DNA-PD group at 21 and 34 dpc. Despite this, and irrespective of the treatment group, SAV2 was effectively transmitted to the naïve fish during 26-day cohabitation. At 47 dpc, the SAV RNA concentrations in the water were lower in all tanks compared to 34 dpc. In Transmission study 2, none of the DNA-PD immunized cohabitants residing with DNA-PD-vaccinated, pre-challenged fish got infected. In contrast, Oil-PD immunized cohabitants residing with Oil-PD-vaccinated, pre-challenged fish, showed infection levels similar to the naïve cohabitants in Transmission study 1. The results demonstrate that the DNA-PD vaccine may curb the spread of SAV infection as the DNA-PD vaccinated, SAV2 exposed fish, did not spread the infection to cohabiting DNA-PD vaccinated fish. This signifies that herd immunity may be achieved by the DNA-PD vaccine, a valuable tool to control the PD epizootic in farmed Atlantic salmon.
Collapse
Affiliation(s)
| | | | - Jeffrey C. Wolf
- Experimental Pathology Laboratories Inc., Sterling, VA, United States
| | | | - Eystein Skjerve
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Espen Rimstad
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Øystein Evensen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | |
Collapse
|
3
|
Lagadec E, Mjølnerød EB, Jensen ØM, Plarre H, Nylund A. Multiple Aeromonas strains isolated from Atlantic salmon (Salmo salar) displaying red skin disease signs in Scandinavian rivers. JOURNAL OF FISH DISEASES 2024; 47:e13870. [PMID: 37800856 DOI: 10.1111/jfd.13870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023]
Abstract
Since 2014, Atlantic salmon (Salmo salar L.) displaying clinical signs of red skin disease (RSD), including haemorrhagic and ulcerative skin lesions, have been repeatedly observed in Swedish rivers. Although the disease has since been reported in other countries, including Norway, Denmark, Ireland and the UK, no pathogen has so far been conclusively associated with RSD. In this study, the presence of 17 fish pathogens was investigated through qPCR in 18 returning Atlantic salmon with clinical signs of the disease in rivers in Sweden and Norway between 2019 and 2021. Several potential pathogens were repeatedly detected, including a protozoan (Ichthyobodo spp.), an oomycete (Saprolegnia spp.) and several bacteria (Yersinia ruckeri, Candidatus Branchiomonas cysticola, Aeromonas spp.). Cultivation on different media from ulcers and internal organs revealed high concentrations of rod-shaped bacteria typical of Aeromonadaceae. Multilocus phylogenetic analysis of different clones and single gene phylogenies of sequences obtained from the fish revealed concurrent isolation of several bacterial strains belonging to the species A. bestiarum, A. piscicola and A. sobria. While these bacterial infections may be secondary, these findings are significant for future studies on RSD and should guide the investigation of future outbreaks. However, the involvement of Aeromonas spp. as putative primary etiological agents of the disease cannot be ruled out and needs to be assessed by challenge experiments.
Collapse
Affiliation(s)
- Erwan Lagadec
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Even Bysveen Mjølnerød
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Øyvind Marius Jensen
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Heidrun Plarre
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Are Nylund
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Bergen, Norway
| |
Collapse
|
4
|
Madhun AS, Nilsen R, Barlaup BT, Karlsen Ø, Karlsbakk E. Occurrence of salmonid alphavirus and piscine orthoreovirus-1 infections in migrating salmon (Salmo salar L.) post-smolt in western Norway. JOURNAL OF FISH DISEASES 2024; 47:e13874. [PMID: 37828712 DOI: 10.1111/jfd.13874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/14/2023]
Abstract
Viral diseases are a serious problem in Atlantic salmon (Salmo salar L.) farming in Norway, often leading to reduced fish welfare and increased mortality. Disease outbreaks in salmon farms may lead to spread of viruses to the surrounding environment. There is a public concern that viral diseases may negatively affect the wild salmon populations. Pancreas disease (PD) caused by salmonid alphavirus (SAV) and heart and skeletal muscle inflammation (HSMI) caused by piscine orthoreovirus-1 (PRV-1) are common viral diseases in salmon farms in western Norway. In the current study, we investigated the occurrence of SAV and PRV-1 infections in 651 migrating salmon post-smolt collected from three fjord systems (Sognefjorden, Osterfjorden and Hardangerfjorden) located in western Norway in 2013 and 2014 by real-time RT-PCR. Of the collected post-smolts, 303 were of wild origin and 348 were hatchery-released. SAV was not detected in any of the tested post-smolt, but PRV-1 was detected in 4.6% of them. The Ct values of PRV-1 positive fish were usually high (mean 32.0; range: 20.1-36.8). PRV-1 prevalence in post-smolts from the three fjords was 6.1% in Sognefjorden followed by 4.8% in Osterfjorden and 2.3% in Hardangerfjorden. The prevalence PRV-1 was significantly higher in wild (6.9%) compared to hatchery-released post-smolt (2.6%). The occurrence of PRV-1 infection in the fish was lowest in the Hardangerfjorden which has the highest fish farming intensity. Our results suggest that SAV infection are uncommon in migrating smolt while PRV-1 infection can be detected at low level. These findings suggest that migrating smolts were at low risk from SAV or PRV-1 released from salmon farms located in their migration routes in 2013 and 2014.
Collapse
Affiliation(s)
| | - Rune Nilsen
- Institute of Marine Research, Bergen, Norway
| | - Bjørn T Barlaup
- Laboratory for Freshwater Ecology and Inland Fisheries, NORCE Norwegian Research Centre, Bergen, Norway
| | | | - Egil Karlsbakk
- Institute of Marine Research, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| |
Collapse
|
5
|
Biasini L, Zamperin G, Pascoli F, Abbadi M, Buratin A, Marsella A, Panzarin V, Toffan A. Transcriptome Profiling of Oncorhynchus mykiss Infected with Low or Highly Pathogenic Viral Hemorrhagic Septicemia Virus (VHSV). Microorganisms 2023; 12:57. [PMID: 38257883 PMCID: PMC10821180 DOI: 10.3390/microorganisms12010057] [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: 11/28/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/24/2024] Open
Abstract
The rainbow trout (Oncorhynchus mykiss) is the most important produced species in freshwater within the European Union, usually reared in intensive farming systems. This species is highly susceptible to viral hemorrhagic septicemia (VHS), a severe systemic disease widespread globally throughout the world. Viral hemorrhagic septicemia virus (VHSV) is the etiological agent and, recently, three classes of VHSV virulence (high, moderate, and low) have been proposed based on the mortality rates, which are strictly dependent on the viral strain. The molecular mechanisms that regulate VHSV virulence and the stimulated gene responses in the host during infection are not completely unveiled. While some preliminary transcriptomic studies have been reported in other fish species, to date there are no publications on rainbow trout. Herein, we report the first time-course RNA sequencing analysis on rainbow trout juveniles experimentally infected with high and low VHSV pathogenic Italian strains. Transcriptome analysis was performed on head kidney samples collected at different time points (1, 2, and 5 days post infection). A large set of notable genes were found to be differentially expressed (DEGs) in all the challenged groups (e.s. trim63a, acod1, cox-2, skia, hipk1, cx35.4, ins, mtnr1a, tlr3, tlr7, mda5, lgp2). Moreover, the number of DEGs progressively increased especially during time with a greater amount found in the group infected with the high VHSV virulent strain. The gene ontology (GO) enrichment analysis highlighted that functions related to inflammation were modulated in rainbow trout during the first days of VHSV infection, regardless of the pathogenicity of the strain. While some functions showed slight differences in enrichments between the two infected groups, others appeared more exclusively modulated in the group challenged with the highly pathogenic strain.
Collapse
|
6
|
Tartor H, Bernhardt LV, Mohammad SN, Kuiper R, Weli SC. In Situ Detection of Salmonid Alphavirus 3 (SAV3) in Tissues of Atlantic Salmon in a Cohabitation Challenge Model with a Special Focus on the Immune Response to the Virus in the Pseudobranch. Viruses 2023; 15:2450. [PMID: 38140691 PMCID: PMC11080939 DOI: 10.3390/v15122450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Salmonid alphavirus strain 3 is responsible for outbreaks of pancreas disease in salmon and rainbow trout in Norway. Although the extensive amount of research on SAV3 focused mainly on the heart and pancreas (of clinical importance), tropism and pathogenesis studies of the virus in other salmon tissues are limited. Here, we used a combination of RT-qPCR (Q_nsp1 gene) and in situ hybridization (RNAscope®) to demonstrate the tropism of SAV3 in situ in tissues of Atlantic salmon, employing a challenge model (by cohabitation). In addition, as previous results suggested that the pseudobranch may harbor the virus, the change in the expression of different immune genes upon SAV3 infection (RT-qPCR) was focused on the pseudobranch in this study. In situ hybridization detected SAV3 in different tissues of Atlantic salmon during the acute phase of the infection, with the heart ventricle showing the most extensive infection. Furthermore, the detection of the virus in different adipose tissues associated with the internal organs of the salmon suggests a specific affinity of SAV3 to adipocyte components. The inconsistent immune response to SAV3 in the pseudobranch after infection did not mitigate the infection in that tissue and is probably responsible for the persistent low infection at 4 weeks post-challenge. The early detection of SAV3 in the pseudobranch after infection, along with the persistent low infection over the experimental infection course, suggests a pivotal role of the pseudobranch in SAV3 pathogenesis in Atlantic salmon.
Collapse
Affiliation(s)
- Haitham Tartor
- Department of Fish Health, Norwegian Veterinary Institute, 1433 Ås, Norway;
| | | | | | - Raoul Kuiper
- Department of Fish Biosecurity, Norwegian Veterinary Institute, 1433 Ås, Norway; (R.K.); (S.C.W.)
| | - Simon C. Weli
- Department of Fish Biosecurity, Norwegian Veterinary Institute, 1433 Ås, Norway; (R.K.); (S.C.W.)
| |
Collapse
|
7
|
Kannimuthu D, Roh H, Peñaranda MMD, Wessel Ø, Mæhle S, Berhe GD, Nordbø J, Kvamme BO, Morton HC, Grove S. Long-term persistence of piscine orthoreovirus-1 (PRV-1) infection during the pre-smolt stages of Atlantic salmon in freshwater. Vet Res 2023; 54:69. [PMID: 37644605 PMCID: PMC10463814 DOI: 10.1186/s13567-023-01201-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/07/2023] [Indexed: 08/31/2023] Open
Abstract
Piscine orthoreovirus (PRV) causes heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon. During salmon production cycles, HSMI has predominantly been observed after seawater transfer. More recently, better surveillance and longitudinal studies have detected occurrences of PRV-1 in freshwater broodstock farms and hatcheries. However, very little is known about the viral kinetics of PRV-1 or disease development of HSMI during these pre-smolt stages. In this study, we conducted a long-term PRV-1 challenge experiment to examine the profile of viral load, infectiousness and/or clearance in Atlantic salmon during their development from fry to parr stage. Atlantic salmon fry (mean weight: 1.1 ± 0.19 g) were infected with PRV-1 (high virulent variant) via intraperitoneal (IP) injection. The viral load reached a peak at 2-4 weeks post-challenge (wpc) in heart and muscle tissues. The virus was detected at relatively high levels in whole blood, spleen, and head kidney tissues until 65 wpc. Heart and muscle lesions typical of HSMI were clearly observed at 6 and 8 wpc but then subsided afterwards resolving inflammation. Innate and adaptive immune responses were elicited during the early/acute phase but returned to basal levels during the persistent phase of infection. Despite achieving high viremia, PRV-1 infection failed to cause any mortality during the 65-week virus challenge period. Cohabitation of PRV-1 infected fish (10 and 31 wpc) with naïve Atlantic salmon fry resulted in very low or no infection. Moreover, repeated chasing stress exposures did not affect the viral load or shedding of PRV-1 at 26 and 44 wpc. The present findings provide knowledge about PRV-1 infection in juvenile salmon and highlight the importance of continued monitoring and management to prevent and mitigate the PRV-1 infection in freshwater facilities.
Collapse
Affiliation(s)
| | - HyeongJin Roh
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| | | | - Øystein Wessel
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - Stig Mæhle
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| | | | - Joachim Nordbø
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| | - Bjørn Olav Kvamme
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| | - H Craig Morton
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| | - Søren Grove
- Institute of Marine Research, Nordnes, P.O. Box 1870, N-5817, Bergen, Norway
| |
Collapse
|
8
|
Thorarinsson R, Wolf JC, Inami M, Sindre H, Skjerve E, Evensen Ø, Rimstad E. Effects of a DNA and multivalent oil-adjuvanted vaccines against pancreas disease in Atlantic salmon (Salmo salar) challenged with salmonid alphavirus subtype 3. FISH AND SHELLFISH IMMUNOLOGY REPORTS 2022; 3:100063. [PMID: 36419608 PMCID: PMC9680106 DOI: 10.1016/j.fsirep.2022.100063] [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: 05/19/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 12/03/2022] Open
Abstract
Efficacy of a DNA- and conventional vaccines against pancreas disease is compared. Higher neutralization antibody levels in the DNA vaccine group compared to controls. Significantly lower viremia levels in the DNA vaccine group than the controls. Efficacy against disease-induced growth loss and damage in target organs is shown . Mortality levels low and not significantly different from the control group.
Salmonid alphavirus (SAV) causes pancreas disease (PD) in Atlantic salmon (Salmo salar). In seawater-farmed salmonids in the southern part of Norway SAV subtype 3 (SAV3) is dominating. PD continues to cause significant economic and fish health concerns in this region despite years of extensive use of oil-adjuvanted vaccines (OAVs) containing inactivated whole virus (IWV) antigens. In the current study, three commercially available PD vaccines were tested. Group A got a DNA vaccine (DNAV) injected intramuscularly (i.m.) plus an OAV without a PD component injected intraperitoneally (i.p.). Groups B and C got different OAV IWV vaccines injected i.p., respectively. The control group was i.p. injected with saline. Approximately 12 weeks after vaccination, the post smolt groups were challenged in seawater with SAV3 by cohabitation. Samples were collected pre-challenge, and at 19, 54 and 83 days post-challenge (dpc). There were no differences in growth or visible intraperitoneal side effects between the immunized groups prior to challenge. Fish in group A had significantly higher SAV3 neutralizing antibody titers than the other groups pre-challenge and significantly lower SAV3 viremia levels than the control group at 19 dpc. Fish in group A had significantly more weight gain than the other groups measured at 54 and 83 dpc. Prevalence and severity of heart necrosis at 19 dpc and loss of exocrine pancreas tissue at 54 and 83 dpc were significantly lower in groups A and B compared to group C and controls. The cumulative mortality in the control group during the challenge period was 10.5%. Group A experienced the lowest mortality (6.4%) albeit not statistically different from the controls. The results suggest that DNAV may reduce the clinical and economic impact of PD by improved protection against SAV3-induced changes in pancreas tissue and growth impairment.
Collapse
|
9
|
Fritsvold C, Mikalsen AB, Poppe TT, Taksdal T, Sindre H. Characterization of an outbreak of cardiomyopathy syndrome (CMS) in young Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2021; 44:2067-2082. [PMID: 34569072 DOI: 10.1111/jfd.13521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Cardiomyopathy syndrome (CMS) is the most common viral cardiac disease in Norwegian Atlantic salmon farming and typically affects large, market size fish. Only six months after seawater transfer, Atlantic salmon were diagnosed with CMS at a fish farm in the south-western part of Norway. Due to the unexpected young age and the remarkable large amounts of virus-specific RNA (Ct <10), the fish group was monitored with five additional samplings until slaughtered almost 10 months later. At three weeks after the first CMS diagnosis (weeks post-diagnosis, wpd) and at slaughter (39 wpd), more comprehensive samplings were performed of the study cage, with specific focus on three different cardiac compartments. The clinical, autopsy and histopathological findings at first diagnosis and at all succeeding samplings were similar to previous descriptions of typical CMS. A slightly elevated mortality was observed in the cage with diseased fish at the time of the first CMS diagnosis and continued throughout the study. The prevalence and load of PMCV-specific RNA in the fish remained high until slaughtering, with similar amounts in all sampled cardiac compartments. No fish from the other five cages at the site were diagnosed with CMS, until fish sampled from the last cage at the site were diagnosed 10 weeks after slaughtering of the study cage (49 wpd). Sequence analysis of the PMCV on the site showed that the outbreak virus was similar to PMCV variants previously sequenced from Norwegian field outbreaks. In conclusion, CMS in young Atlantic salmon had clinical signs and histopathological cardiac lesions typical for the disease, and diseased fish could be found in the study cage until slaughtering.
Collapse
Affiliation(s)
| | - Aase B Mikalsen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Trygve T Poppe
- Norwegian Veterinary Institute, Oslo, Norway
- PHARMAQ Analytiq AS, Bergen, Norway
| | | | | |
Collapse
|
10
|
Bernhardt LV, Lillehaug A, Qviller L, Weli SC, Grønneberg E, Nilsen H, Myrmel M. Early detection of salmonid alphavirus in seawater from marine farm sites of Atlantic salmon Salmo salar. DISEASES OF AQUATIC ORGANISMS 2021; 146:41-52. [PMID: 34498609 DOI: 10.3354/dao03618] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The traditional strategy for national surveillance of salmonid alphavirus (SAV) infection in Norwegian fish farms relies on a costly, time-consuming, and resource-demanding approach based on the monthly sampling of fish from all marine farms with salmonids. In order to develop an alternative surveillance method, a water filtration method was tested in parallel with the ongoing surveillance program at 7 Norwegian marine farm sites of Atlantic salmon Salmo salar L. with no current suspicion of SAV infection. During the period from May 2019 to January 2020, seawater samples were collected from the top layer water inside all net-pens at these 7 sites. The samples were concentrated for SAV by filtration through an MF-Millipore™ electronegative membrane filter, followed by rinsing with NucliSENS® Lysis Buffer, before RNA extraction and analysis by RT-qPCR. SAV was detected from seawater at an earlier stage compared to traditional sampling methods, at all sites where the fish tested positive for SAV. A significant negative relationship was observed at all sites between the SAV concentration found in seawater samples and the number of days until SAV was detected in the fish. This means that the fewer the SAV particles in the seawater, the more days it took until SAV was detected in the fish samples. Based on this, sampling of seawater every month for the surveillance of SAV has a great potential as an alternative method for early detection of SAV in Atlantic salmon farms.
Collapse
|
11
|
Aksnes I, Braaen S, Markussen T, Åkesson CP, Villoing S, Rimstad E. Genetically modified attenuated salmonid alphavirus: A potential strategy for immunization of Atlantic salmon. JOURNAL OF FISH DISEASES 2021; 44:923-937. [PMID: 33591590 DOI: 10.1111/jfd.13352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/29/2021] [Accepted: 01/31/2021] [Indexed: 06/12/2023]
Abstract
Pancreas disease (PD) is a serious challenge in European salmonid aquaculture caused by salmonid alphavirus (SAV). In this study, we report the effect of immunization of Atlantic salmon with three attenuated infectious SAV3 strains with targeted mutations in a glycosylation site of the envelope E2 protein and/or in a nuclear localization signal in the capsid protein. In a pilot experiment, it was shown that the mutated viral strains replicated in fish, transmitted to naïve cohabitants and that the transmission had not altered the sequences. In the main experiment, the fish were immunized with the strains and challenged with SAV3 eight weeks after immunization. Immunization resulted in infection both in injected fish and 2 weeks later in the cohabitant fish, followed by a persistent but declining load of the mutated virus variants in the hearts. The immunized fish developed clinical signs and pathology consistent with PD prior to challenge. However, fish injected with the virus mutated in both E2 and capsid showed little clinical signs and had higher average weight gain than the groups immunized with the single mutated variants. The SAV strain used for challenge was not detected in the immunized fish indicating that these fish were protected against superinfection with SAV during the 12 weeks of the experiment.
Collapse
Affiliation(s)
- Ida Aksnes
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Stine Braaen
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Turhan Markussen
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | | | | | - Espen Rimstad
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| |
Collapse
|
12
|
Nylund A, Røed M, Blindheim S, Trösse C, Andersen L. Experimental challenge of Atlantic salmon Salmo salar using clones of Paramoeba perurans, P. pemaquidensis and Tetramitus sp. DISEASES OF AQUATIC ORGANISMS 2021; 145:1-13. [PMID: 34080578 DOI: 10.3354/dao03597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Salmon gill disease in Norway is in most cases associated with a range of different pathogens, stress and environmental factors. Paramoeba perurans and other amoebae have been isolated during such disease outbreaks. Other amoebae isolated from salmon with gill disease in Norway include P. pemaquidensis, Tetramitus sp. and Vannella sp. Here we tested the pathogenicity of the first 2 species in challenge experiments. We found that even when clonal cultures of P. pemaquidensis established an infection on the gills of salmon, it failed to cause gill disease, while Tetramitus sp. appeared to be unable to establish a lasting infection on the gills of healthy salmon. The result of the challenge with P. pemaquidensis confirms the results of similar studies performed in the USA and in Australia. Tetramitus sp. is probably a common amoeba in the marine environment, and its presence on the gills of farmed salmon may just be accidental. Based on this study, we conclude that P. perurans is the only known amoeba in marine salmon farming associated with amoebic gill disease in Norway.
Collapse
Affiliation(s)
- Are Nylund
- Department of Biology University of Bergen, 5020 Bergen, Norway
| | | | | | | | | |
Collapse
|
13
|
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.
Collapse
|
14
|
Effects of ploidy and salmonid alphavirus infection on the skin and gill microbiome of Atlantic salmon (Salmo salar). PLoS One 2021; 16:e0243684. [PMID: 33606747 PMCID: PMC7894865 DOI: 10.1371/journal.pone.0243684] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/01/2021] [Indexed: 01/04/2023] Open
Abstract
The microbial communities that live in symbiosis with the mucosal surfaces of animals provide the host with defense strategies against pathogens. These microbial communities are largely shaped by the environment and the host genetics. Triploid Atlantic salmon (Salmo salar) are being considered for aquaculture as they are reproductively sterile and thus cannot contaminate the natural gene pool. It has not been previously investigated how the microbiome of triploid salmon compares to that of their diploid counterparts. In this study, we compare the steady-state skin and gill microbiome of both diploid and triploid salmon, and determine the effects of salmonid alphavirus 3 experimental infection on their microbial composition. Our results show limited differences in the skin-associated microbiome between triploid and diploid salmon, irrespective of infection. In the gills, we observed a high incidence of the bacterial pathogen Candidatus Branchiomonas, with higher abundance in diploid compared to triploid control fish. Diploid salmon infected with SAV3 showed greater histopathological signs of epitheliocystis compared to controls, a phenomenon not observed in triploid fish. Our results indicate that ploidy can affect the alpha diversity of the gills but not the skin-associated microbial community. Importantly, during a natural outbreak of Branchiomonas sp. the gill microbiome of diploid Atlantic salmon became significantly more dominated by this pathogen than in triploid animals. Thus, our results suggest that ploidy may play a role on Atlantic salmon gill health and provide insights into co-infection with SAV3 and C. Branchiomonas in Atlantic salmon.
Collapse
|
15
|
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.
Collapse
|
16
|
Thorarinsson R, Wolf JC, Inami M, Phillips L, Jones G, Macdonald AM, Rodriguez JF, Sindre H, Skjerve E, Rimstad E, Evensen Ø. Effect of a novel DNA vaccine against pancreas disease caused by salmonid alphavirus subtype 3 in Atlantic salmon (Salmo salar). FISH & SHELLFISH IMMUNOLOGY 2021; 108:116-126. [PMID: 33285168 DOI: 10.1016/j.fsi.2020.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/29/2020] [Accepted: 12/01/2020] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) caused by salmonid alphavirus subtype 3 (SAV3) is a serious disease with large economic impact on farmed Norwegian Atlantic salmon production despite years of use of oil-adjuvanted vaccines against PD (OAVs). In this study, two commercially available PD vaccines, a DNA vaccine (DNAV) and an OAV, were compared in an experimental setting. At approximately 1040° days (dd) at 12 °C post immunization, the fish were challenged with SAV3 by cohabitation 9 days after transfer to sea water. Sampling was done prior to challenge and at 19, 54, and 83 days post-challenge (dpc). When compared to the OAV and control (Saline) groups, the DNAV group had significantly higher SAV3 neutralizing antibody titers after the immunization period, significantly lower SAV3 viremia levels at 19 dpc, significantly reduced transmission of SAV3 to naïve fish in the latter part of the viremic phase, significantly higher weight gain post-challenge, and significantly reduced prevalence and/or severity of SAV-induced morphologic changes in target organs. The DNAV group had also significantly higher post-challenge survival compared to the Saline group, but not to the OAV group. The data suggest that use of DNAV may reduce the economic impact of PD by protecting against destruction of the pancreas tissue and subsequent growth impairment which is the most common and costly clinical outcome of this disease.
Collapse
Affiliation(s)
| | - Jeffrey C Wolf
- Experimental Pathology Laboratories Inc., 45600 Terminal Drive, Sterling, VA, 20166, USA.
| | - Makoto Inami
- VESO Vikan, Beisvågveien 108, Vikan, N-7810, Namsos, Norway.
| | - Lisa Phillips
- Elanco Canada Ltd., 37 McCarville Street, Charlottetown, PE C1E 2A7, Canada.
| | - Ginny Jones
- Elanco Canada Ltd., 37 McCarville Street, Charlottetown, PE C1E 2A7, Canada.
| | - Alicia M Macdonald
- Elanco Canada Ltd., 37 McCarville Street, Charlottetown, PE C1E 2A7, Canada.
| | - Jose F Rodriguez
- Elanco Canada Ltd., 37 McCarville Street, Charlottetown, PE C1E 2A7, Canada.
| | - Hilde Sindre
- Norwegian Veterinary Institute, Ullevålsveien 68, N-0454, Oslo, Norway.
| | - Eystein Skjerve
- Norwegian University of Life Sciences, School of Veterinary Medicine, Ullevålsveien 72, N-0454, Oslo, Norway.
| | - Espen Rimstad
- Norwegian University of Life Sciences, School of Veterinary Medicine, Ullevålsveien 72, N-0454, Oslo, Norway.
| | - Øystein Evensen
- Norwegian University of Life Sciences, School of Veterinary Medicine, Ullevålsveien 72, N-0454, Oslo, Norway.
| |
Collapse
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Munir D, Munro ES, Secombes CJ, Dooley H. Atlantic salmon kidney (ASK) cells are an effective model to characterise interferon (IFN) and IFN-induced gene expression following salmonid alphavirus infection. FISH & SHELLFISH IMMUNOLOGY 2020; 106:792-795. [PMID: 32871248 DOI: 10.1016/j.fsi.2020.08.043] [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: 07/01/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Salmonid alphavirus (SAV), the causative agent of pancreas disease, is a serious pathogen of farmed Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Given the economic impact of SAV outbreaks, much effort is focussed upon understanding the fish immune response following infection and the exploitation of this knowledge to reduce disease impact. Herein we examine the utility of the long-term Atlantic salmon kidney (ASK) cell line as a tool to study antiviral responses upon infection with SAV. Following infection with SAV subtype 1 (isolate V4640) we examined the kinetics and magnitude of induction of IFNa, IFN-regulatory factor (IRF) genes IRF1, IRF3, and IRF7b, as well as the antiviral effector Mx by RT-qPCR. SAV-1 non-structural protein (nsp1) transcript levels increased continuously over the experimental period, indicating viral replication, but cytopathic effect (CPE) was not observed. All the immune genes studied showed an increase in transcript levels over the 96-h study period following SAV infection, with strongest induction of Mx. Our data confirm that ASK cells are a suitable model to study the virus-associated immune responses of salmonids and may be a useful tool when assaying the effectiveness of potential prophylactic or antiviral treatments.
Collapse
Affiliation(s)
- Danish Munir
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK; Scottish Fish Immunology Research Centre, University of Aberdeen, Aberdeen, UK
| | - Eann S Munro
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
| | - Christopher J Secombes
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK; Scottish Fish Immunology Research Centre, University of Aberdeen, Aberdeen, UK
| | - Helen Dooley
- Dept Microbiology & Immunology, University of Maryland School of Medicine, Institute of Marine & Environmental Technology, Baltimore, USA.
| |
Collapse
|
19
|
Teige LH, Aksnes I, Røsæg MV, Jensen I, Jørgensen J, Sindre H, Collins C, Collet B, Rimstad E, Dahle MK, Boysen P. Detection of specific Atlantic salmon antibodies against salmonid alphavirus using a bead-based immunoassay. FISH & SHELLFISH IMMUNOLOGY 2020; 106:374-383. [PMID: 32738513 DOI: 10.1016/j.fsi.2020.07.055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
Salmonid alphavirus (SAV) is the etiological cause of pancreas disease (PD) in Atlantic salmon (Salmo salar). Several vaccines against SAV are in use, but PD still cause significant mortality and concern in European aquaculture, raising the need for optimal tools to monitor SAV immunity. To monitor and control the distribution of PD in Norway, all salmonid farms are regularly screened for SAV by RT-qPCR. While the direct detection of SAV is helpful in the early stages of infection, serological methods could bring additional information on acquired SAV immunity in the later stages. Traditionally, SAV antibodies are monitored in neutralization assays, but they are time-consuming and cumbersome, thus alternative assays are warranted. Enzyme-linked immunosorbent assays (ELISAs) have not yet been successfully used for anti-SAV antibody detection in aquaculture. We aimed to develop a bead-based immunoassay for SAV-specific antibodies. By using detergent-treated SAV particles as antigens, we detected SAV-specific antibodies in plasma collected from both a SAV challenge trial and a field outbreak of PD. Increased levels of SAV-specific antibodies were seen after most fish had become negative for viral RNA. The bead-based assay is time saving compared to virus neutralization assays, and suitable for non-lethal testing due to low sample size requirements. We conclude that the bead-based immunoassay for SAV antibody detection is a promising diagnostic tool to complement SAV screening in aquaculture.
Collapse
Affiliation(s)
- Lena Hammerlund Teige
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | - Ida Aksnes
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | | | - Ingvill Jensen
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Jorunn Jørgensen
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Hilde Sindre
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
| | - Catherine Collins
- Université Paris-Saclay, INRAE, UVSQ, VIM, 78350, Jouy-en-Josas, France
| | - Bertrand Collet
- Université Paris-Saclay, INRAE, UVSQ, VIM, 78350, Jouy-en-Josas, France
| | - Espen Rimstad
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | - Maria K Dahle
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway; Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
| | - Preben Boysen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway.
| |
Collapse
|
20
|
Weli SC, Bernhardt LV, Qviller L, Myrmel M, Lillehaug A. Development and evaluation of a method for concentration and detection of salmonid alphavirus from seawater. J Virol Methods 2020; 287:113990. [PMID: 33035567 DOI: 10.1016/j.jviromet.2020.113990] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/25/2020] [Accepted: 10/02/2020] [Indexed: 12/31/2022]
Abstract
Waterborne viral infections represent a major threat to fish health. For many viruses, understanding the interplay between pathogens, host and environment presents a major hurdle for transmission. Salmonid alphavirus (SAV) can infect and cause pancreas disease (PD) in farmed salmonids in seawater. During infection, SAV is excreted from infected fish to the seawater. We evaluated two types of filters and four different eluents, for concentration of SAV3. One L of seawater was spiked with SAV3, followed by filtration and virus elution from membrane filters. For the negatively charged MF hydrophilic membrane filter (MF-) combined with NucliSENS® lysis buffer the SAV3 recovery was 39.5 ± 1.8 % by RT-ddPCR and 25.9 ± 5.7 % by RT-qPCR. The recovery using the positively charged 1 MDS Zeta Plus® Virosorb® membrane filter (MD+), combined with NucliSENS® lysis buffer was 19.0 ± 0.1 % by RT-ddPCR and 13.3 ± 3.8 % by RT-qPCR. The limits of quantification (LOQ) and detection (LOD) were estimated to be 5.18 × 103 and 2.0 × 102 SAV3 copies/L of natural seawater, by RT-ddPCR. SAV3 recovery from small volumes of seawater, and the requirement for standard laboratory equipment, suggest the MF-filter combined with NucliSENS® lysis buffer would be a candidate for further validation in experimental trials.
Collapse
Affiliation(s)
- Simon Chioma Weli
- Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway.
| | | | - Lars Qviller
- Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway.
| | - Mette Myrmel
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Virology Unit, P.O. Box 8146 Dep., N-0033 Oslo, Norway.
| | - Atle Lillehaug
- Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway.
| |
Collapse
|
21
|
Aksnes I, Markussen T, Braaen S, Rimstad E. Mutation of N-glycosylation Sites in Salmonid Alphavirus (SAV) Envelope Proteins Attenuate the Virus in Cell Culture. Viruses 2020; 12:v12101071. [PMID: 32987930 PMCID: PMC7650630 DOI: 10.3390/v12101071] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/16/2022] Open
Abstract
Salmonid alphavirus (SAV) is the cause of pancreas disease and sleeping disease in farmed salmonid fish in Europe. The spread of these diseases has been difficult to control with biosecurity and current vaccination strategies, and increased understanding of the viral pathogenesis could be beneficial for the development of novel vaccine strategies. N-glycosylation of viral envelope proteins may be crucial for viral virulence and a possible target for its purposed attenuation. In this study, we mutated the N-glycosylation consensus motifs of the E1 and E2 glycoproteins of a SAV3 infectious clone using site-directed mutagenesis. Mutation of the glycosylation motif in E1 gave a complete inactivation of the virus as no viral replication could be detected in cell culture and infectious particles could not be rescued. In contrast, infectious virus particles could be recovered from the SAV3 E2 mutants (E2319Q, E2319A), but not if they were accompanied by lack of N-glycosylation in E1. Compared to the non-mutated infectious clone, the SAV3-E2319Q and SAV3-E2319A recombinant viruses produced less cytopathic effects in cell culture and lower amounts of infectious viral particles. In conclusion, the substitution in the N-linked glycosylation site in E2 attenuated SAV3 in cell culture. The findings could be useful for immunization strategies using live attenuated vaccines and testing in fish will be desirable to study the clone’s properties in vivo.
Collapse
|
22
|
Jenberie S, Peñaranda MMD, Thim HL, Styrvold MB, Strandskog G, Jørgensen JB, Jensen I. Salmonid Alphavirus Subtype 3 Induces Prolonged Local B Cell Responses in Atlantic Salmon ( Salmo salar) After Intraperitoneal Infection. Front Immunol 2020; 11:1682. [PMID: 33013821 PMCID: PMC7511533 DOI: 10.3389/fimmu.2020.01682] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/24/2020] [Indexed: 11/13/2022] Open
Abstract
B cell responses are a crucial part of the adaptive immune response to viral infection. Infection by salmonid alphavirus subtype 3 (SAV3) causes pancreas disease (PD) in Atlantic salmon (Salmo salar) and is a serious concern to the aquaculture industry. In this study, we have used intraperitoneal (IP) infection with SAV3 as a model to characterize local B cell responses in the peritoneal cavity (PerC) and systemic immune tissues (head kidney/spleen). Intraperitoneal administration of vaccines is common in Atlantic salmon and understanding more about the local PerC B cell response is fundamental. Intraperitoneal SAV3 infection clearly induced PerC B cell responses as assessed by increased frequency of IgM+ B cells and total IgM secreting cells (ASC). These PerC responses were prolonged up to nine weeks post-infection and positively correlated to the anti-SAV3 E2 and to neutralizing antibody responses in serum. For the systemic immune sites, virus-induced changes in B cell responses were more modest or decreased compared to controls in the same period. Collectively, data reported herein indicated that PerC could serve as a peripheral immunological site by providing a niche for prolonged maintenance of the ASC response in Atlantic salmon.
Collapse
Affiliation(s)
- Shiferaw Jenberie
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Ma Michelle D Peñaranda
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Hanna L Thim
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Morten Bay Styrvold
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Guro Strandskog
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Jorunn B Jørgensen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| | - Ingvill Jensen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, The Arctic University of Norway, Tromsø, Norway
| |
Collapse
|
23
|
Marty GD, Bidulka J, Joseph T. Cross-sectional study of histopathology and piscine orthoreovirus during a marine production cycle of farmed Atlantic salmon (Salmo salar L.) in British Columbia, Canada. JOURNAL OF FISH DISEASES 2020; 43:1019-1028. [PMID: 33448429 DOI: 10.1111/jfd.13210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/30/2020] [Accepted: 06/01/2020] [Indexed: 06/12/2023]
Abstract
Two cohorts of farmed Atlantic salmon, Salmo salar L., in British Columbia, Canada, were sampled for histopathology (nine organs) and piscine orthoreovirus (PRV-1) PCR after seawater entry at 2, 4, 6, 8, 10, 13, 16 and 19 months (20 fish per cohort per date). One cohort-from a PRV+ hatchery-remained PRV+ throughout the study (sample prevalence 80%-100%). In an adjacent pen, the other cohort-from a PRV- hatchery-was 0% PRV+ at 78 days, 30% PRV+ at 128 days and ≥95% PRV+ thereafter. Among sample cohorts that were ≥80% PRV+, median Ct values were nominally less among fish sourced from the PRV- hatchery (28.7-33.3) than the PRV+ hatchery (30.8-35.2). No microscopic lesions were associated with PRV Ct value (minimum = 25.6). About 3% of fish in both cohorts had moderate inflammatory heart lesions; among these fish, only one had skeletal muscle inflammation (mild), and PRV Ct values were similar to unaffected cohorts sampled the same day. Also, among 16 moribund or freshly dead fish sampled opportunistically during the study, 14 were PRV+, and none had significant inflammatory heart lesions. These data support the hypothesis that British Columbia PRV-1 does not contribute to mortality.
Collapse
Affiliation(s)
- Gary D Marty
- Animal Health Centre, Ministry of Agriculture, Abbotsford, BC, Canada
| | - Julie Bidulka
- Animal Health Centre, Ministry of Agriculture, Abbotsford, BC, Canada
| | - Tomy Joseph
- Animal Health Centre, Ministry of Agriculture, Abbotsford, BC, Canada
| |
Collapse
|
24
|
Bakke AF, Bjørgen H, Koppang EO, Frost P, Afanasyev S, Boysen P, Krasnov A, Lund H. IgM+ and IgT+ B Cell Traffic to the Heart during SAV Infection in Atlantic Salmon. Vaccines (Basel) 2020; 8:E493. [PMID: 32878234 PMCID: PMC7563723 DOI: 10.3390/vaccines8030493] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 02/02/2023] Open
Abstract
B cells of teleost fish differentiate in the head kidney, and spleen, and either remain in the lymphatic organs or move to the blood and peripheral tissues. There is limited knowledge about piscine B cell traffic to sites of vaccination and infection and their functional roles at these sites. In this work, we examined the traffic of B cells in Atlantic salmon challenged with salmonid alphavirus (SAV). In situ hybridization (RNAScope) showed increased numbers of immunoglobin (Ig)M+ and IgT+ B cells in the heart in response to SAV challenge, with IgM+ B cells being most abundant. An increase in IgT+ B cells was also evident, indicating a role of IgT+ B cells in nonmucosal tissues and systemic viral infections. After infection, B cells were mainly found in the stratum spongiosum of the cardiac ventricle, colocalizing with virus-infected myocardial-like cells. From sequencing the variable region of IgM in the main target organ (heart) and comparing it with a major lymphatic organ (the spleen), co-occurrence in antibody repertoires indicated a transfer of B cells from the spleen to the heart, as well as earlier recruitment of B cells to the heart in vaccinated fish compared to those that were unvaccinated. Transcriptome analyses performed at 21 days post-challenge suggested higher expression of multiple mediators of inflammation and lymphocyte-specific genes in unvaccinated compared to vaccinated fish, in parallel with a massive suppression of genes involved in heart contraction, metabolism, and development of tissue. The adaptive responses to SAV in vaccinated salmon appeared to alleviate the disease. Altogether, these results suggest that migration of B cells from lymphatic organs to sites of infection is an important part of the adaptive immune response of Atlantic salmon to SAV.
Collapse
Affiliation(s)
- Anne Flore Bakke
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Håvard Bjørgen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Erling Olaf Koppang
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Petter Frost
- MSD Animal Health Innovation AD, Thormøhlens Gate 55, 5006 Bergen, Norway;
| | - Sergey Afanasyev
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Torez 44, Saint-Petersburg 194223, Russia;
| | - Preben Boysen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | | | - Hege Lund
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| |
Collapse
|
25
|
Health Surveillance of Wild Brown Trout ( Salmo trutta fario) in the Czech Republic Revealed a Coexistence of Proliferative Kidney Disease and Piscine Orthoreovirus-3 Infection. Pathogens 2020; 9:pathogens9080604. [PMID: 32722219 PMCID: PMC7460431 DOI: 10.3390/pathogens9080604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/17/2020] [Accepted: 07/21/2020] [Indexed: 01/05/2023] Open
Abstract
The population of brown trout (Salmo trutta fario) in continental Europe is on the decline, with infectious diseases confirmed as one of the causative factors. However, no data on the epizootiological situation of wild fish in the Czech Republic are currently available. In this study, brown trout (n = 260) from eight rivers were examined for the presence of viral and parasitical pathogens. Salmonid alphavirus-2, infectious pancreatic necrosis virus, piscine novirhabdovirus (VHSV) and salmonid novirhabdovirus (IHNV) were not detected using PCR. Cell culturing showed no viruses as well, and serological analysis of 110 sera did not detect any specific antibodies against VHSV or IHNV. Fish from two rivers were positive for the presence of piscine orthoreovirus-3 (PRV-3), subtype PRV-3b. However, none of the PRV-3-positive fish showed gross pathologies typically associated with PRV infections. By far the most widespread pathogen was Tetracapsuloides bryosalmonae which was confirmed in each of the examined locations, with a prevalence of up to 65% and 100%, as established by immunohistochemistry and PCR, respectively. Furthermore, up to 43.8% of fish showed signs of proliferative kidney disease caused by T. bryosalmonae, suggesting that this parasite is a main health challenge for brown trout in the Czech Republic.
Collapse
|
26
|
Dahle OMV, Blindheim SH, Nylund A, Karlsbakk E, Breck O, Glosvik H, Andersen L. Atlantic salmon Salmo salar and ballan wrasse Labrus bergylta display different susceptibility to clonal strains of Paramoeba perurans. DISEASES OF AQUATIC ORGANISMS 2020; 140:55-72. [PMID: 32614331 DOI: 10.3354/dao03483] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Amoebic gill disease (AGD), caused by the marine amoeba Paramoeba perurans, is an important disease of farmed Atlantic salmon Salmo salar L. in Norway. The use of wrasse as cleaner fish in salmon net pens raises questions about interspecies transmission of pathogens such as P. perurans. In this study, cohabitant transmission of clonal isolates of P. perurans between Atlantic salmon and ballan wrasse Labrus bergylta Ascanius was examined, using isolates originating from both salmon and wrasse. The challenges resulted in AGD in both species, although less severely in wrasse. The amoeba isolate originating from ballan wrasse was more virulent than that originating from salmon, suggesting P. perurans strain-related virulence differences. The isolate originating from salmon showed limited proliferation in bath-challenged wrasse and salmon, and limited transfer to cohabitants. Our results support previous observations suggesting that salmon may be more susceptible to P. perurans and AGD than ballan wrasse. Treatment of P. perurans infection in wrasse is challenging, as it is a strictly marine fish species. In this study, brackish water (<15‰ seawater) treatment of AGD affected salmon and wrasse was examined. Both salmon and wrasse were treated for short periods (3 h and 24 h), and treatment of wrasse over longer periods (3-5 d) was also examined. Short exposure to brackish water was not enough to remove P. perurans, although the 24 h treatment reduced amoeba levels. It was not possible to culture or detect P. perurans from wrasse exposed to brackish water for 3 d, suggesting that this treatment would be effective in controlling the parasite.
Collapse
Affiliation(s)
- O M V Dahle
- Department of Biology, University of Bergen, 5020 Bergen, Norway
| | | | | | | | | | | | | |
Collapse
|
27
|
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.
Collapse
|
28
|
Schachner O, Dinhopl N, Friedl A, Soliman H, El-Matbouli M. Advanced vacuolation indicates propagation of various salmonid alphavirus type 2 isolates in Acholeplasma-infected BF-2 cells. DISEASES OF AQUATIC ORGANISMS 2020; 139:189-197. [PMID: 32495745 DOI: 10.3354/dao03481] [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: 06/11/2023]
Abstract
During previous routine inspections of bluegill fry (BF-2) and rainbow trout gonad (RTG-2) cells incubated with organ samples from asymptomatic Arctic char Salvelinus alpinus, brook trout Salvelinus fontinalis, and rainbow trout Oncorhynchus mykiss, a distinctive, reproducible cytopathic effect (CPE) appeared. The striking CPE, involving progressive vacuolation turning into slowly proceeding pyknotic degeneration, was originally attributed exclusively to enhanced growth of Acholeplasma sp. However, at a recent re-examination of re-infected BF-2 cells using electron microscopy (EM), conventional PCR, and quantitative PCR (qPCR), a virus was also detected. Two days post inoculation (dpi), EM revealed characteristic virions inside cytoplasmic vacuoles and next to bacteria outside the cells. The nucleotide sequences of the viral nsP3 gene fragment obtained from supernatants of infected cells were 100% identical and representative for salmonid alphavirus type 2 (SAV 2). The 16S RNA gene (16S rDNA) fragment sequences of the Mollicutes-specific PCR product obtained from SAV-infected as well as virus-free BF-2 control cells were identical with Acholeplasma laidlawii. In addition, qPCR results indicated enhanced propagation of virus and bacteria increasing with vacuolation between 5 and 8 dpi. Advanced vacuolation can be regarded as a CPE of both SAV and A. laidlawii, suggesting a viral impact on the bacterial infection that turns a latent intracellular stage into an apparent degenerative condition.
Collapse
Affiliation(s)
- O Schachner
- Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria
| | | | | | | | | |
Collapse
|
29
|
Robinson NA, Krasnov A, Burgerhout E, Johnsen H, Moghadam HK, Hillestad B, Aslam ML, Baranski M, Boison SA. Response of the Salmon Heart Transcriptome to Pancreas Disease: Differences Between High- and Low-Ranking Families for Resistance. Sci Rep 2020; 10:868. [PMID: 31964968 PMCID: PMC6972705 DOI: 10.1038/s41598-020-57786-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 01/07/2020] [Indexed: 12/30/2022] Open
Abstract
Pancreas disease caused by salmonid alphaviruses leads to severe losses in Atlantic salmon aquaculture. The aim of our study was to gain a better understanding of the biological differences between salmon with high and low genomic breeding values (H-gEBV and L-gEBV respectively) for pancreas disease resistance. Fish from H- and L-gEBV families were challenged by intraperitoneal injection of salmonid alphavirus or co-habitation with infected fish. Mortality was higher with co-habitation than injection, and for L- than H-gEBV. Heart for RNA-seq and histopathology was collected before challenge and at four- and ten-weeks post-challenge. Heart damage was less severe in injection-challenged H- than L-gEBV fish at week 4. Viral load was lower in H- than L-gEBV salmon after co-habitant challenge. Gene expression differences between H- and L-gEBV manifested before challenge, peaked at week 4, and moderated by week 10. At week 4, H-gEBV salmon showed lower expression of innate antiviral defence genes, stimulation of B- and T-cell immune function, and weaker stress responses. Retarded resolution of the disease explains the higher expression of immune genes in L-gEBV at week 10. Results suggest earlier mobilization of acquired immunity better protects H-gEBV salmon by accelerating clearance of the virus and resolution of the disease.
Collapse
Affiliation(s)
- N A Robinson
- Breeding and Genetics, Nofima, Ås, 1430, Norway. .,Sustainable Aquaculture Laboratory- Temperate and Tropical (SALTT), School of BioSciences, The University of Melbourne, Parkville, 3010, Australia.
| | - A Krasnov
- Breeding and Genetics, Nofima, Ås, 1430, Norway
| | | | - H Johnsen
- Breeding and Genetics, Nofima, Ås, 1430, Norway
| | | | | | - M L Aslam
- Breeding and Genetics, Nofima, Ås, 1430, Norway
| | | | | |
Collapse
|
30
|
Jansen MD, Guarracino M, Carson M, Modahl I, Taksdal T, Sindre H, Brun E, Tavornpanich S. Field Evaluation of Diagnostic Test Sensitivity and Specificity for Salmonid Alphavirus (SAV) Infection and Pancreas Disease (PD) in Farmed Atlantic salmon ( Salmo salar L.) in Norway Using Bayesian Latent Class Analysis. Front Vet Sci 2019; 6:419. [PMID: 31850380 PMCID: PMC6893554 DOI: 10.3389/fvets.2019.00419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/07/2019] [Indexed: 01/02/2023] Open
Abstract
Salmonid alphavirus (SAV) is the OIE-listed, viral cause of pancreas disease (PD) in farmed Atlantic salmon. SAV is routinely detected by PCR–methods while typical histopathological lesions are additionally used to confirm the diagnosis. Field evaluation of diagnostic test performance is essential to ensure confidence in a test's ability to predict the infection or disease status of a target animal. For most tests used in aquaculture, characteristics like sensitivity (Se) and specificity (Sp) at the analytical level may be known. Few tests are, however, evaluated at the diagnostic level according to the OIE standard. In the present work, we estimated diagnostic test sensitivity (DSe) and diagnostic test specificity (DSp) for five laboratory tests used for SAV detection. As there is no gold standard, the study was designed using Bayesian latent class analysis. Real-time RT-PCR, cell culture, histopathology, virus neutralization test, and immunohistochemistry were compared using samples taken from three different farmed Atlantic salmon populations with different infection status; one population regarded negative, one in an early stage of infection, and one in a later stage of infection. The average fish weight in the three populations was 2.0, 1.6, and 1.5 kg, respectively. The DSe and DSp of real-time RT-PCR is of particular interest due to its common use as a screening tool. The method showed high DSe (≥0.977) and moderate DSp (0.831) in all 3-populations models. The results further suggest that a follow-up test of serum samples in real-time RT-PCR negative populations may be prudent in cases where epidemiological information suggest a high risk of infection and where a false negative result is of high consequence. This study underlines the need to choose a test appropriate for the purpose of the testing. In the case of a weak positive PCR-result, a follow-up test should be conducted to verify the presence of SAV. Cell culture showed high DSe and DSp and may be used to verify viral presence.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Edgar Brun
- Norwegian Veterinary Institute, Oslo, Norway
| | | |
Collapse
|
31
|
Svenning S, Gondek-Wyrozemska AT, van der Wal YA, Robertsen B, Jensen I, Jørgensen JB, Edholm ES. Microbial Danger Signals Control Transcriptional Induction of Distinct MHC Class I L Lineage Genes in Atlantic Salmon. Front Immunol 2019; 10:2425. [PMID: 31681311 PMCID: PMC6797598 DOI: 10.3389/fimmu.2019.02425] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 09/27/2019] [Indexed: 11/13/2022] Open
Abstract
Antigen processing and presentation by major histocompatibility complex (MHC) molecules is a cornerstone in vertebrate immunity. Like mammals, teleosts possess both classical MHC class I and multiple families of divergent MHC class I genes. However, while certain mammalian MHC class I-like molecules have proven to be integral in immune regulation against a broad array of pathogens, the biological relevance of the different MHC class I lineages in fish remains elusive. This work focuses on MHC class I L lineage genes and reveals unique regulatory patterns of six genes (Sasa-lia, Sasa-lda, Sasa-lca, Sasa-lga, Sasa-lha, and Sasa-lfa) in antimicrobial immunity of Atlantic salmon (Salmo salar L.). Using two separate in vivo challenge models with different kinetics and immune pathologies combined with in vitro stimulation using viral and bacterial TLR ligands, we show that de novo synthesis of different L lineage genes is distinctly regulated in response to various microbial stimuli. Prior to the onset of classical MHC class I gene expression, lia was rapidly and systemically induced in vivo by the single-stranded (ss) RNA virus salmonid alpha virus 3 (SAV3) but not in response to the intracellular bacterium Piscirickettsia salmonis. In contrast, lga expression was upregulated in response to both viral and bacterial stimuli. A role for distinct MHC class I L-lineage genes in anti-microbial immunity in salmon was further substantiated by a marked upregulation of lia and lga gene expression in response to type I IFNa stimulation in vitro. Comparably, lha showed no transcriptional induction in response to IFNa stimulation but was strongly induced in response to a variety of viral and bacterial TLR ligands. In sharp contrast, lda showed no response to viral or bacterial challenge. Similarly, induction of lca, which is predominantly expressed in primary and secondary lymphoid tissues, was marginal with the exception of a strong and transient upregulation in pancreas following SAV3 challenge Together, these findings suggest that certain Atlantic salmon MHC class I L lineage genes play important and divergent roles in early anti-microbial response and that their regulation, in response to different activation signals, represents a system for selectively promoting the expression of distinct non-classical MHC class I genes in response to different types of immune challenges.
Collapse
Affiliation(s)
- Steingrim Svenning
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Agata T Gondek-Wyrozemska
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Yorick Andreas van der Wal
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway.,Vaxxinova Research & Development, Vaxxinova GmbH, Münster, Germany
| | - Børre Robertsen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Ingvill Jensen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Jorunn B Jørgensen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Eva-Stina Edholm
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries & Economics, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| |
Collapse
|
32
|
Teffer AK, Miller KM. A Comparison of Nonlethal and Destructive Methods for Broad-Based Infectious Agent Screening of Chinook Salmon Using High-Throughput qPCR. JOURNAL OF AQUATIC ANIMAL HEALTH 2019; 31:274-289. [PMID: 31343778 DOI: 10.1002/aah.10079] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 07/20/2019] [Indexed: 06/10/2023]
Abstract
Molecular tools, such as high-throughput quantitative polymerase chain reaction (HT-qPCR), are useful for monitoring multiple infectious agents in wild animal populations (i.e., broad-based screening). If destructive tissue samples cannot be obtained due to experimental design requirements (e.g., bio-telemetry; holding with repeated biopsy) or the conservation status of host species, then nonlethally sampled tissues can be substituted. However, infection profiles have been found to differ between nonlethally and destructively sampled tissues. We present a comparative analysis of nonlethal (gill and blood) and destructive (pool of internal and external tissue) approaches for broad-based infectious agent screening of adult Chinook Salmon Oncorhynchus tshawytscha. Of a possible 47 agents, 16 were detected overall by nonlethal and destructive methods. Our results indicated moderate differences in infection profiles among tissues, with limitations of each tissue type dependent on the ecology of each agent. The gill was the most comprehensive screening tissue, as more infectious agents were detected overall in gill (n = 16) than in blood (n = 12) or multi-tissue pools (n = 15). The agreement in the estimated agent prevalence between tissue types ranged from poor to excellent, while overall agent community structure (the combined prevalence of all agents) showed low agreement between tissue types. Two agents occurred at 100% prevalence in all tissue types. Nine agents, including types of bacteria and gill parasites, were more prevalent in gill than in blood, while five agents, including one virus and several microparasites, were more prevalent in blood. Future studies should pair microscopy and histopathology with HT-qPCR to better characterize host health and disease development relative to molecular detection of agents across tissue types.
Collapse
Affiliation(s)
- Amy K Teffer
- Department of Biology, University of Victoria, Post Office Box 1700, Station CSC, Victoria, British Columbia, V8W 2Y2, Canada
| | - Kristina M Miller
- Fisheries and Oceans Canada, Molecular Genetics Section, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia, V9T 6N7, Canada
| |
Collapse
|
33
|
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.
Collapse
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
| |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- E Lewisch
- Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria
| | | | | | | | | | | |
Collapse
|
35
|
Shi W, Wang Y, Ren X, Gao S, Hua X, Guo M, Tang L, Xu Y, Ren T, Li Y, Liu M. EvaGreen-based real-time PCR assay for sensitive detection of salmonid alphavirus. Mol Cell Probes 2018; 39:7-13. [DOI: 10.1016/j.mcp.2018.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/10/2018] [Accepted: 03/15/2018] [Indexed: 10/17/2022]
|
36
|
Madhun AS, Isachsen CH, Omdal LM, Einen ACB, Maehle S, Wennevik V, Niemelä E, Svåsand T, Karlsbakk E. Prevalence of piscine orthoreovirus and salmonid alphavirus in sea-caught returning adult Atlantic salmon (Salmo salar L.) in northern Norway. JOURNAL OF FISH DISEASES 2018; 41:797-803. [PMID: 29388217 DOI: 10.1111/jfd.12785] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/29/2017] [Accepted: 12/29/2017] [Indexed: 06/07/2023]
Abstract
Heart and skeletal muscle inflammation (HSMI) caused by piscine orthoreovirus (PRV) and pancreas disease (PD) caused by salmonid alphavirus (SAV) are among the most prevalent viral diseases of Atlantic salmon farmed in Norway. There are limited data about the impact of disease in farmed salmon on wild salmon populations. Therefore, the prevalence of PRV and SAV in returning salmon caught in six sea sites was determined using real-time RT-PCR analyses. Of 419 salmon tested, 15.8% tested positive for PRV, while none were positive for SAV. However, scale reading revealed that 10% of the salmon had escaped from farms. The prevalence of PRV in wild salmon (8%) was significantly lower than in farm escapees (86%), and increased with fish length (proxy for age). Sequencing of the S1 gene of PRV from 39 infected fish revealed a mix of genotypes. The observed increase in PRV prevalence with fish age and the lack of phylogeographic structure of the virus could be explained by virus transmission in the feeding areas. Our results highlight the need for studies about the prevalence of PRV and other pathogens in Atlantic salmon in its oceanic phase.
Collapse
Affiliation(s)
- A S Madhun
- Institute of Marine Research, Bergen, Norway
| | | | - L M Omdal
- Institute of Marine Research, Bergen, Norway
| | - A C B Einen
- Institute of Marine Research, Bergen, Norway
| | - S Maehle
- Institute of Marine Research, Bergen, Norway
| | - V Wennevik
- Institute of Marine Research, Bergen, Norway
| | - E Niemelä
- Natural Resources Institute Finland (Luke), Helsinki, Finland
| | - T Svåsand
- Institute of Marine Research, Bergen, Norway
| | - E Karlsbakk
- Institute of Marine Research, Bergen, Norway
- Department of Biology, University of Bergen, Bergen, Norway
| |
Collapse
|
37
|
Abstract
Salmonid alphavirus (SAV), genus Alphavirus, family Togaviridae, is a single-stranded RNA virus affecting Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). It is known to be responsible for pancreas disease (PD) and sleeping disease (SD) which are increasing problems, causing high fish mortality and economic losses in the European aquaculture industry. Pancreas disease was first described in Atlantic salmon in Scotland in 1976 and a similar disease caused by the closely related sleeping disease virus was first described in rainbow trout in France. There have also been reports of salmonid alphavirus infections from other European countries, including Ireland, England, Norway, Germany, Italy, and Spain. Salmonid alphaviruses have been classified into six subtypes (SAV1–6). SAV1 and SAV4–6 cause pancreas disease in Atlantic salmon in Ireland or Scotland, SAV2 is the causative agent of sleeping disease in rainbow trout, and SAV3 has been detected in Atlantic salmon in Norway. The aim of this paper was to summarise current knowledge of infections caused by salmonid alphavirus and diagnostic methods including the newest techniques, and to briefly describe prevention from SAV infections by vaccination.
Collapse
|
38
|
Purcell MK, Powers RL, Evered J, Kerwin J, Meyers TR, Stewart B, Winton JR. Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus in Alaska and Washington. JOURNAL OF FISH DISEASES 2018; 41:347-355. [PMID: 29159930 DOI: 10.1111/jfd.12740] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 06/07/2023]
Abstract
This research was initiated in conjunction with a systematic, multiagency surveillance effort in the United States (U.S.) in response to reported findings of infectious salmon anaemia virus (ISAV) RNA in British Columbia, Canada. In the systematic surveillance study reported in a companion paper, tissues from various salmonids taken from Washington and Alaska were surveyed for ISAV RNA using the U.S.-approved diagnostic method, and samples were released for use in this present study only after testing negative. Here, we tested a subset of these samples for ISAV RNA with three additional published molecular assays, as well as for RNA from salmonid alphavirus (SAV), piscine myocarditis virus (PMCV) and piscine orthoreovirus (PRV). All samples (n = 2,252; 121 stock cohorts) tested negative for RNA from ISAV, PMCV, and SAV. In contrast, there were 25 stock cohorts from Washington and Alaska that had one or more individuals test positive for PRV RNA; prevalence within stocks varied and ranged from 2% to 73%. The overall prevalence of PRV RNA-positive individuals across the study was 3.4% (77 of 2,252 fish tested). Findings of PRV RNA were most common in coho (Oncorhynchus kisutch Walbaum) and Chinook (O. tshawytscha Walbaum) salmon.
Collapse
Affiliation(s)
- M K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - R L Powers
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - J Evered
- U.S. Fish and Wildlife Service, Olympia Fish Health Center, Lacey, WA, USA
| | - J Kerwin
- Washington Department of Fish and Wildlife, Olympia, WA, USA
| | - T R Meyers
- Division of Commercial Fisheries, Alaska Department of Fish and Game, Juneau, AK, USA
| | - B Stewart
- Northwest Indian Fisheries Commission, Olympia, WA, USA
| | - J R Winton
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| |
Collapse
|
39
|
Büyükekiz AG, Altun S, Hansen EF, Satıcıoğlu IB, Duman M, Markussen T, Rimstad E. Infectious pancreatic necrosis virus (IPNV) serotype Sp is prevalent in Turkish rainbow trout farms. JOURNAL OF FISH DISEASES 2018; 41:95-104. [PMID: 28745835 DOI: 10.1111/jfd.12675] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 06/07/2023]
Abstract
Infectious pancreatic necrosis virus (IPNV) is a common pathogen of rainbow trout (Oncorhynchus mykiss) in Turkey. We found that 455 of 1,676 sample pools tested were IPNV positive. Positive samples were found in all geographical regions where sampling was conducted. Sequence and phylogenetic analyses of VP2 from 30 isolates representing all regions showed that the viruses were highly similar in sequence and grouped within Genogroup 5 (serotype Sp-A2). No correlations between sequences, sampling sites or geographical origins were identified. Although clinical disease was evident in several farms, analyses of the amino acid sequence of VP2 showed that all virus strains harboured the P217 T221 motif, assumed to be associated with low virulence. We conclude that IPNV is prevalent in Turkish rainbow trout farms and that the viruses are very homogenous and likely to be of European origin. Frequent exchange of eggs and live fish within the farming industry may explain the homogeneity of the IPNV.
Collapse
Affiliation(s)
- A G Büyükekiz
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - S Altun
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - E F Hansen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - I B Satıcıoğlu
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - M Duman
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - T Markussen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - E Rimstad
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| |
Collapse
|
40
|
Scholz F, Ruane NM, Morrissey T, Marcos-López M, Mitchell S, O'Connor I, Mirimin L, MacCarthy E, Rodger HD. Piscine myocarditis virus detected in corkwing wrasse (Symphodus melops) and ballan wrasse (Labrus bergylta). JOURNAL OF FISH DISEASES 2018; 41:147-152. [PMID: 28791724 DOI: 10.1111/jfd.12661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
Affiliation(s)
- F Scholz
- FishVet Group Ireland, Oranmore, Co. Galway, Ireland
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - N M Ruane
- Fish Health Unit, Marine Institute, Oranmore, Co. Galway, Ireland
| | - T Morrissey
- Fish Health Unit, Marine Institute, Oranmore, Co. Galway, Ireland
| | - M Marcos-López
- FishVet Group Ireland, Oranmore, Co. Galway, Ireland
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - S Mitchell
- FishVet Group Ireland, Oranmore, Co. Galway, Ireland
| | - I O'Connor
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - L Mirimin
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - E MacCarthy
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - H D Rodger
- FishVet Group Ireland, Oranmore, Co. Galway, Ireland
| |
Collapse
|
41
|
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.
Collapse
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
| |
Collapse
|
42
|
Hauge H, Vendramin N, Taksdal T, Olsen AB, Wessel Ø, Mikkelsen SS, Alencar ALF, Olesen NJ, Dahle MK. Infection experiments with novel Piscine orthoreovirus from rainbow trout (Oncorhynchus mykiss) in salmonids. PLoS One 2017; 12:e0180293. [PMID: 28678799 PMCID: PMC5497981 DOI: 10.1371/journal.pone.0180293] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 06/13/2017] [Indexed: 01/12/2023] Open
Abstract
A new disease in farmed rainbow trout (Onchorhyncus mykiss) was described in Norway in 2013. The disease mainly affected the heart and resembled heart and skeletal muscle inflammation (HSMI) in Atlantic salmon (Salmo salar L.). HSMI is associated with Piscine orthoreovirus (PRV), and a search for a similar virus in the diseased rainbow trout led to detection of a sequence with 85% similarity to PRV. This finding called for a targeted effort to assess the risk the new PRV-variant pose on farmed rainbow trout and Atlantic salmon by studying infection and disease pathogenesis, aiming to provide more diagnostic knowledge. Based on the genetic relationship to PRV, the novel virus is referred to as PRV-Oncorhynchus mykiss (PRV-Om) in contrast to PRV-Salmo salar (PRV-Ss). In experimental trials, intraperitoneally injected PRV-Om was shown to replicate in blood in both salmonid species, but more effectively in rainbow trout. In rainbow trout, the virus levels peaked in blood and heart of cohabitants 6 weeks post challenge, along with increased expression of antiviral genes (Mx and viperin) in the spleen, with 80-100% of the cohabitants infected. Heart inflammation was diagnosed in all cohabitants examined 8 weeks post challenge. In contrast, less than 50% of the Atlantic salmon cohabitants were infected between 8 and 16 weeks post challenge and the antiviral response in these fish was very low. From 12 weeks post challenge and onwards, mild focal myocarditis was demonstrated in a few virus-positive salmon. In conclusion, PRV-Om infects both salmonid species, but faster transmission, more notable antiviral response and more prominent heart pathology were observed in rainbow trout.
Collapse
Affiliation(s)
- Helena Hauge
- Norwegian Veterinary Institute, Oslo & Bergen, Norway
| | - Niccolo Vendramin
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | | | | | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | | | | | - Niels Jørgen Olesen
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | | |
Collapse
|
43
|
Cao Y, Tveten AK, Stene A. Establishment of a non-invasive method for stress evaluation in farmed salmon based on direct fecal corticoid metabolites measurement. FISH & SHELLFISH IMMUNOLOGY 2017; 66:317-324. [PMID: 28433720 DOI: 10.1016/j.fsi.2017.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/20/2017] [Accepted: 04/18/2017] [Indexed: 06/07/2023]
Abstract
Fish welfare is an important issue for growth of the aquaculture industry. Stress responses represent animal's natural reactions to challenging conditions and could be used as a welfare indicator. Cortisol level is relevant to fish welfare condition, and is a readily measured component of the primary stress response system. Generally, cortisol is measured by blood sampling. However, fish blood cortisol level could be instantly influenced by handling-stress at sampling. Fecal corticoid metabolites (FCM) are a mixture of several different metabolites with a wide range of polarities. Thus, feces could be promising alternative less handling-sensitive and non-invasive biological matrices for cortisol evaluation in Atlantic salmon. In this study we developed non-invasive method for determination of fecal corticoid metabolites in farmed Atlantic salmon (Salmo salar L.) using enzyme-linked immunosorbent assay (ELISA). It was demonstrated that salmon FCM extracted from salmon feces is insoluble in non-polar solvents like diethyl ether, but well soluble in polar solvents like methanol. The proper extraction ratio could be one ml 100% methanol for 100 μL of the liquid part of salmon feces or 100 mg of the solid part. The FCM directly detected in unextracted liquid part of feces correlated well with the FCM extracted from both liquid and solid part of the corresponding samples, without significant difference. Thus, it is feasible to measure FCM directly in the liquid part of salmon feces without any extraction procedure. Then, we applied this assay for FCM analysis in the group of salmon that experienced salmon pancreas disease (PD) and amoebic gill disease (AGD). We demonstrated 1) both plasma cortisol and FCM increased significantly during the outbreak of inflammatory disease (P < 0.01). Plasma cortisol level was elevated from 28 ± 40 ng/ml to 164.4 ± 62.5 ng/ml, FCM from 14.4 ± 13.2 ng/ml to 170.7 ± 89.7 ng/ml 2) Growth and starvation has no significant impact on either cortisol or FCM level. 3) FCM correlated well with plasma cortisol level (P < 0.01). Furthermore, there seems more individual variation in plasma cortisol levels than in FCM levels. These results suggest FCM could be directly analyzed in liquid part of salmon feces without extraction. This directly detected FCM level could represent the total fecal FCM level and plasma cortisol level. This simple and non-invasive method makes FCM a proper indicator for salmon welfare.
Collapse
Affiliation(s)
- Yanran Cao
- Faculty of Natural Sciences, Department of Biological Sciences Ålesund, Norwegian University of Science and Technology, Ålesund, Norway.
| | - Ann-Kristin Tveten
- Faculty of Natural Sciences, Department of Biological Sciences Ålesund, Norwegian University of Science and Technology, Ålesund, Norway
| | - Anne Stene
- Faculty of Natural Sciences, Department of Biological Sciences Ålesund, Norwegian University of Science and Technology, Ålesund, Norway
| |
Collapse
|
44
|
Røsaeg MV, Sindre H, Persson D, Breck O, Knappskog D, Olsen AB, Taksdal T. Ballan wrasse (Labrus bergylta Ascanius) is not susceptible to pancreas disease caused by salmonid alphavirus subtype 2 and 3. JOURNAL OF FISH DISEASES 2017; 40:975-978. [PMID: 27859355 DOI: 10.1111/jfd.12572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/23/2016] [Accepted: 09/23/2016] [Indexed: 06/06/2023]
Affiliation(s)
- M V Røsaeg
- SalMar ASA, Kverva, Norway
- Norwegian University of Life Sciences, Oslo, Norge
| | - H Sindre
- Norwegian Veterinary Institute, Oslo, Norge
| | - D Persson
- Norwegian University of Life Sciences, Oslo, Norge
- FoMas - Fiskehelse og miljø, Haugesund, Norway
| | - O Breck
- Marine Harvest Norway AS, Bergen, Norway
| | - D Knappskog
- MSD Animal Health, Bergen, Norway
- Vaxxinova Norway AS, Bergen, Norway
| | - A B Olsen
- Norwegian Veterinary Institute, Oslo, Norge
| | - T Taksdal
- Norwegian Veterinary Institute, Oslo, Norge
| |
Collapse
|
45
|
Andreassen R, Woldemariam NT, Egeland IØ, Agafonov O, Sindre H, Høyheim B. Identification of differentially expressed Atlantic salmon miRNAs responding to salmonid alphavirus (SAV) infection. BMC Genomics 2017; 18:349. [PMID: 28472924 PMCID: PMC5418855 DOI: 10.1186/s12864-017-3741-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Background MicroRNAs (miRNAs) control multiple biological processes including the innate immune responses by negative post-transcriptional regulation of gene expression. As there were no studies on the role(s) of miRNAs in viral diseases in Atlantic salmon, we aimed to identify miRNAs responding to salmonid alphavirus (SAV) infection. Their expression were studied at different time points post infection with SAV isolates associated with different mortalities. Furthermore, the genome sequences of the identified miRNAs were analysed to reveal putative cis-regulatory elements, and, finally, their putative target genes were predicted. Results Twenty differentially expressed miRNAs (DE miRNAs) were identified. The expression of the majority of these increased post infection with maximum levels reached after the viral load were stabilized or decreasing. On the other hand, some miRNAs (e.g. the miRNA-21 family) showed decreased expression at the early time points post infection. There were significant differences in the temporal expression of individual miRNA associated with different SAV isolates. Target gene prediction in SAV responsive immune network genes showed that seventeen of the DE miRNAs could target 24 genes (e.g. IRF3, IRF7). Applying the Atlantic salmon transcriptome as input 28 more immune network genes were revealed as putative targets (e.g. IRF5, IRF4). The majority of the predicted target genes promote inflammatory response. The upstream sequences of the miRNA genes revealed a high density of cis-regulatory sequences known as binding sites for immune network transcription factors (TFs). A high expression in the late phase could therefore be due to increased transcription promoted by immune response activated TFs. Based on the in silico target predictions, we discuss their putative roles as early promotors or late inhibitors of inflammation. We propose that the differences in expressions associated with different SAV isolates could contribute to their differences in mortality rates. Conclusions This study represents the first steps in exploring miRNAs important in viral-host interaction in Atlantic salmon. We identified several miRNAs responding to SAV infection. Some likely to prohibit harmful inflammation while other may promote an early immune response. Their predicted functions need to be validated and further studied in functional assays to fully understand their roles in immune homeostasis. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3741-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Rune Andreassen
- Department of Pharmacy and Biomedical and Laboratory Sciences, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Pilestredet 50, N-0130, Oslo, Norway.
| | - Nardos Tesfaye Woldemariam
- Department of Pharmacy and Biomedical and Laboratory Sciences, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Pilestredet 50, N-0130, Oslo, Norway
| | - Ine Østråt Egeland
- Department of Pharmacy and Biomedical and Laboratory Sciences, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Pilestredet 50, N-0130, Oslo, Norway
| | - Oleg Agafonov
- Bioinformatics Core Facility, Department of Core Facilities, Institute of Cancer Research, Radium hospital, part of Oslo University Hospital, Oslo, Norway
| | - Hilde Sindre
- Norwegian Veterinary Institute, PB 750 Sentrum, N-106, Oslo, Norway
| | - Bjørn Høyheim
- Department of Basic Sciences and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, 0454, Oslo, Norway
| |
Collapse
|
46
|
Røsæg MV, Lund M, Nyman IB, Markussen T, Aspehaug V, Sindre H, Dahle MK, Rimstad E. Immunological interactions between Piscine orthoreovirus and Salmonid alphavirus infections in Atlantic salmon. FISH & SHELLFISH IMMUNOLOGY 2017; 64:308-319. [PMID: 28323214 DOI: 10.1016/j.fsi.2017.03.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/14/2017] [Accepted: 03/17/2017] [Indexed: 06/06/2023]
Abstract
Heart and skeletal muscle inflammation (HSMI) and pancreas disease (PD) cause substantial losses in Atlantic salmon (Salmo salar) aquaculture. The respective causative agents, Piscine orthoreovirus (PRV) and Salmonid alphavirus (SAV), are widespread and often concurrently present in farmed salmon. An experimental infection in Atlantic salmon was conducted to study the interaction between the two viruses, including the immunological mechanisms involved. The co-infected fish were infected with PRV four or ten weeks before they were infected with SAV. The SAV RNA level and the PD specific lesions were significantly lower in co-infected groups compared to the group infected by only SAV. The expression profiles of a panel of innate antiviral response genes and the plasma SAV neutralization titers were examined. The innate antiviral response genes were in general upregulated for at least ten weeks after the primary PRV infection. Plasma from co-infected fish had lower SAV neutralizing titers compared to the controls infected with only SAV. Plasma from some individuals infected with only PRV neutralized SAV, but heat treatment removed this effect. Field studies of co-infected fish populations indicated a negative correlation between the two viruses in randomly sampled apparently healthy fish, in line with the experimental findings, but a positive correlation in moribund or dead fish. The results indicate that the innate antiviral response induced by PRV may temporary protect against a secondary SAV infection.
Collapse
Affiliation(s)
- Magnus Vikan Røsæg
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway; SalMar ASA, Kverva, Norway
| | - Morten Lund
- Sections of Immunology and Virology, Norwegian Veterinary Institute, Oslo, Norway
| | - Ingvild Berg Nyman
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Turhan Markussen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | | | - Hilde Sindre
- Sections of Immunology and Virology, Norwegian Veterinary Institute, Oslo, Norway
| | - Maria Krudtaa Dahle
- Sections of Immunology and Virology, Norwegian Veterinary Institute, Oslo, Norway
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.
| |
Collapse
|
47
|
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.
Collapse
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.
| |
Collapse
|
48
|
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.
Collapse
|
49
|
Lin Q, Fu X, Liu L, Liang H, Guo H, Yin S, Kumaresan V, Huang Z, Li N. Application and development of a TaqMan real-time PCR for detecting infectious spleen and kidney necrosis virus in Siniperca chuatsi. Microb Pathog 2017; 107:98-105. [PMID: 28323153 DOI: 10.1016/j.micpath.2017.02.046] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/22/2017] [Accepted: 02/27/2017] [Indexed: 11/30/2022]
Abstract
Infectious spleen and kidney necrosis virus (ISKNV) is one of the major epidemiological agents that had caused great economic loss in Chinese perch (Siniperca chuatsi). In this study, a specific TaqMan real-time PCR was developed using a pair of primers and a TaqMan probe specific to the ORF007 gene of ISKNV to rapidly detect ISKNV copies in Chinese perch samples. This assay was optimized to produce linearity from 8.75 × 108 to 8.75 × 101 copies in standard curve with an efficiency of 98% and a R2 value of 0.9999. Moreover, the minimum detection limit of this assay was 10,000 times more sensitive than that of conventional PCR method. The coefficients of variation of intra- and inter-assay repeatability were less than 2.4% and 3.3%, respectively. The viral distribution in different tissues of diseased Chinese perch was evaluated by TaqMan real-time PCR method and the highest level of viral copies was detected in spleen. Among the 76 diseased Chinese perch clinical samples, 35 and 29 were positive samples based on the TaqMan real-time PCR and conventional PCR methods, respectively, indicating that the TaqMan real-time PCR was more sensitive than conventional PCR. Therefore, the TaqMan real-time PCR should be a useful tool for the early surveillance and quantitation of ISKNV.
Collapse
Affiliation(s)
- Qiang Lin
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Xiaozhe Fu
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Lihui Liu
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Hongru Liang
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Huizhi Guo
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Shuwen Yin
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Venkatesh Kumaresan
- Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China
| | - Zhibin Huang
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China
| | - Ningqiu Li
- Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380, China.
| |
Collapse
|
50
|
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.
Collapse
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.
| |
Collapse
|