The Experts below are selected from a list of 29094 Experts worldwide ranked by ideXlab platform
M F Mcloughlin - One of the best experts on this subject based on the ideXlab platform.
-
the epidemiology of Pancreas Disease in salmonid aquaculture a summary of the current state of knowledge
Journal of Fish Diseases, 2017Co-Authors: Mona Dverdal Jansen, M F Mcloughlin, D A Graham, H D Rodger, Britt Bang Jensen, T Taksdal, H Sindre, Atle LillehaugAbstract:Pancreas Disease (PD) is a viral Disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the Disease itself and to factors contributing to agent spread and Disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated Disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.
-
the serum proteome of atlantic salmon salmo salar during Pancreas Disease pd following infection with salmonid alphavirus subtype 3 sav3
Journal of Proteomics, 2013Co-Authors: M Braceland, M F Mcloughlin, D A Graham, R Bickerdike, John Tinsley, D Cockerill, Richard Burchmore, William Weir, C Wallace, P D EckersallAbstract:Salmonid alphavirus is the aetological agent of Pancreas Disease (PD) in marine Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, with most outbreaks in Norway caused by SAV subtype 3 (SAV3). This atypical alphavirus is transmitted horizontally causing a significant economic impact on the aquaculture industry. This histopathological and proteomic study, using an established cohabitational experimental model, investigated the correlation between tissue damage during PD and a number of serum proteins associated with these pathologies in Atlantic salmon. The proteins were identified by two-dimensional electrophoresis, trypsin digest and peptide MS/MS fingerprinting. A number of humoral components of immunity which may act as biomarkers of the Disease were also identified. For example, creatine kinase, enolase and malate dehydrogenase serum concentrations were shown to correlate with pathology during PD. In contrast, hemopexin, transferrin, and apolipoprotein, amongst others, altered during later stages of the Disease and did not correlate with tissue pathologies. This approach has given new insight into not only PD but also fish Disease as a whole, by characterisation of the protein response to infection, through pathological processes to tissue recovery.
-
a comparative study of marine salmonid alphavirus subtypes 1 6 using an experimental cohabitation challenge model
Journal of Fish Diseases, 2011Co-Authors: D A Graham, H M Rowley, P Frost, Kirsty Mclaughlin, I Gabestad, A Gordon, M F McloughlinAbstract:A comparative challenge study of six marine isolates representing subtypes 1-6 of salmonid alphavirus (salmon Pancreas Disease virus, Genus Alphavirus, Family Togaviridae) was conducted in Atlantic salmon in a fresh water cohabitation trial. Histopathological lesions typical of Pancreas Disease were observed with all subtypes, and virus was re-isolated from serum of cohabitant fish in each case. Using a virus neutralization (VN) test neutralizing salmonid alphavirus (SAV) subtype 1 strain F93-125, VN antibodies were detected in all challenge groups, consistent with serological cross-reactivity between these subtypes. Using real-time RT-PCR, SAV RNA was detected in heart tissue from 2 to 3 weeks post-challenge (wpc) in all cohabitant groups excluding controls. The results obtained suggested differences in the dynamics of infection between strains of SAV and potentially between subtypes. Results for SAV subtypes 1 and 3 suggested essentially synchronous infection of cohabitant fish. These two study groups also had the highest virus load in heart tissue as measured by quantitative RT-PCR and also had the most extensive histopathological changes. In contrast, results for SAV subtypes 2 and 6 strains were consistent with asynchronous infection in the cohabitant fish and were characterized by slow spread, low virus loads and mild histopathological changes. The SAV subtype 4 and 5 strains occupied an intermediate position in this regard. Despite the use of concentration procedures, it was not possible to detect SAV RNA in water samples from selected study tanks. However, testing of faeces from the SAV subtypes 1, 3 and 6 challenge groups found positive signals in each beginning at 1-3 wpc and remaining detectable for a further 2-3 weeks. Parallel testing of mucus samples found these became positive at 2-3 wpc and remained positive for a further 1-3 weeks. These results demonstrate for the first time that shedding and transmission of virus may occur by both these routes and suggest that dispersal in these matrices should be included in any Disease transmission models.
-
alphavirus infections in salmonids a review
Journal of Fish Diseases, 2007Co-Authors: M F Mcloughlin, D A GrahamAbstract:The first alphavirus to be isolated from fish was recorded in 1995 with the isolation of salmon Pancreas Disease virus from Atlantic salmon, Salmo salar L., in Ireland. Subsequently, the closely related sleeping Disease virus was isolated from rainbow trout, Oncorhynchus mykiss (Walbaum), in France. More recently Norwegian salmonid alphavirus (SAV) has been isolated from marine phase production of Atlantic salmon and rainbow trout in Norway. These three viruses are closely related and are now considered to represent three subtypes of SAV, a new member of the genus Alphavirus within the family Togaviridae. SAVs are recognized as serious pathogens of farmed Atlantic salmon and rainbow trout in Europe. This paper aims to draw together both historical and current knowledge of the Diseases caused by SAVs, the viruses, their diagnosis and control, and to discuss the differential diagnosis of similar pathologies seen in cardiomyopathy syndrome and heart and skeletal muscle inflammation of Atlantic salmon.
-
Pancreas Disease in farmed atlantic salmon salmo salar l and rainbow trout oncorhynchus mykiss walbaum in norway
Journal of Fish Diseases, 2007Co-Authors: D A Graham, T Taksdal, Anne Berit Olsen, I Bjerkas, M J Hjortaas, Birgit H Dannevig, M F McloughlinAbstract:The present paper describes, for the first time, clinical signs and pathological findings of Pancreas Disease (PD) in farmed Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in sea water in Norway. Similarities and differences with reports of PD from Ireland and Scotland are discussed. Samples of 68 rainbow trout from Disease outbreaks on 14 farms and from 155 Atlantic salmon from outbreaks on 20 farms collected from 1996 to 2004 were included in the present study. The histopathological findings of PD in Atlantic salmon and rainbow trout in sea water were similar. Acute PD, characterized by acute necrosis of exocrine pancreatic tissues, was detected in nine Atlantic salmon and three rainbow trout. Salmonid alphavirus (SAV) was identified in acute pancreatic necroses by immunohistochemistry. Most fish showed severe loss of exocrine pancreatic tissue combined with chronic myositis. Myocarditis was often but not consistently found. Kidneys from 40% and 64% of the rainbow trout and Atlantic salmon, respectively, had cells along the sinusoids that were packed with cytoplasmic eosinophilic granules. These cells resembled hypertrophied endothelial cells or elongated mast cell analogues. Histochemical staining properties and electron microscopy of these cells are presented. SAV was identified by RT-PCR and neutralizing antibodies against SAV were detected in blood samples.
D A Graham - One of the best experts on this subject based on the ideXlab platform.
-
the epidemiology of Pancreas Disease in salmonid aquaculture a summary of the current state of knowledge
Journal of Fish Diseases, 2017Co-Authors: Mona Dverdal Jansen, M F Mcloughlin, D A Graham, H D Rodger, Britt Bang Jensen, T Taksdal, H Sindre, Atle LillehaugAbstract:Pancreas Disease (PD) is a viral Disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the Disease itself and to factors contributing to agent spread and Disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated Disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.
-
the serum proteome of atlantic salmon salmo salar during Pancreas Disease pd following infection with salmonid alphavirus subtype 3 sav3
Journal of Proteomics, 2013Co-Authors: M Braceland, M F Mcloughlin, D A Graham, R Bickerdike, John Tinsley, D Cockerill, Richard Burchmore, William Weir, C Wallace, P D EckersallAbstract:Salmonid alphavirus is the aetological agent of Pancreas Disease (PD) in marine Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, with most outbreaks in Norway caused by SAV subtype 3 (SAV3). This atypical alphavirus is transmitted horizontally causing a significant economic impact on the aquaculture industry. This histopathological and proteomic study, using an established cohabitational experimental model, investigated the correlation between tissue damage during PD and a number of serum proteins associated with these pathologies in Atlantic salmon. The proteins were identified by two-dimensional electrophoresis, trypsin digest and peptide MS/MS fingerprinting. A number of humoral components of immunity which may act as biomarkers of the Disease were also identified. For example, creatine kinase, enolase and malate dehydrogenase serum concentrations were shown to correlate with pathology during PD. In contrast, hemopexin, transferrin, and apolipoprotein, amongst others, altered during later stages of the Disease and did not correlate with tissue pathologies. This approach has given new insight into not only PD but also fish Disease as a whole, by characterisation of the protein response to infection, through pathological processes to tissue recovery.
-
a comparative study of marine salmonid alphavirus subtypes 1 6 using an experimental cohabitation challenge model
Journal of Fish Diseases, 2011Co-Authors: D A Graham, H M Rowley, P Frost, Kirsty Mclaughlin, I Gabestad, A Gordon, M F McloughlinAbstract:A comparative challenge study of six marine isolates representing subtypes 1-6 of salmonid alphavirus (salmon Pancreas Disease virus, Genus Alphavirus, Family Togaviridae) was conducted in Atlantic salmon in a fresh water cohabitation trial. Histopathological lesions typical of Pancreas Disease were observed with all subtypes, and virus was re-isolated from serum of cohabitant fish in each case. Using a virus neutralization (VN) test neutralizing salmonid alphavirus (SAV) subtype 1 strain F93-125, VN antibodies were detected in all challenge groups, consistent with serological cross-reactivity between these subtypes. Using real-time RT-PCR, SAV RNA was detected in heart tissue from 2 to 3 weeks post-challenge (wpc) in all cohabitant groups excluding controls. The results obtained suggested differences in the dynamics of infection between strains of SAV and potentially between subtypes. Results for SAV subtypes 1 and 3 suggested essentially synchronous infection of cohabitant fish. These two study groups also had the highest virus load in heart tissue as measured by quantitative RT-PCR and also had the most extensive histopathological changes. In contrast, results for SAV subtypes 2 and 6 strains were consistent with asynchronous infection in the cohabitant fish and were characterized by slow spread, low virus loads and mild histopathological changes. The SAV subtype 4 and 5 strains occupied an intermediate position in this regard. Despite the use of concentration procedures, it was not possible to detect SAV RNA in water samples from selected study tanks. However, testing of faeces from the SAV subtypes 1, 3 and 6 challenge groups found positive signals in each beginning at 1-3 wpc and remaining detectable for a further 2-3 weeks. Parallel testing of mucus samples found these became positive at 2-3 wpc and remained positive for a further 1-3 weeks. These results demonstrate for the first time that shedding and transmission of virus may occur by both these routes and suggest that dispersal in these matrices should be included in any Disease transmission models.
-
alphavirus infections in salmonids a review
Journal of Fish Diseases, 2007Co-Authors: M F Mcloughlin, D A GrahamAbstract:The first alphavirus to be isolated from fish was recorded in 1995 with the isolation of salmon Pancreas Disease virus from Atlantic salmon, Salmo salar L., in Ireland. Subsequently, the closely related sleeping Disease virus was isolated from rainbow trout, Oncorhynchus mykiss (Walbaum), in France. More recently Norwegian salmonid alphavirus (SAV) has been isolated from marine phase production of Atlantic salmon and rainbow trout in Norway. These three viruses are closely related and are now considered to represent three subtypes of SAV, a new member of the genus Alphavirus within the family Togaviridae. SAVs are recognized as serious pathogens of farmed Atlantic salmon and rainbow trout in Europe. This paper aims to draw together both historical and current knowledge of the Diseases caused by SAVs, the viruses, their diagnosis and control, and to discuss the differential diagnosis of similar pathologies seen in cardiomyopathy syndrome and heart and skeletal muscle inflammation of Atlantic salmon.
-
Pancreas Disease in farmed atlantic salmon salmo salar l and rainbow trout oncorhynchus mykiss walbaum in norway
Journal of Fish Diseases, 2007Co-Authors: D A Graham, T Taksdal, Anne Berit Olsen, I Bjerkas, M J Hjortaas, Birgit H Dannevig, M F McloughlinAbstract:The present paper describes, for the first time, clinical signs and pathological findings of Pancreas Disease (PD) in farmed Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in sea water in Norway. Similarities and differences with reports of PD from Ireland and Scotland are discussed. Samples of 68 rainbow trout from Disease outbreaks on 14 farms and from 155 Atlantic salmon from outbreaks on 20 farms collected from 1996 to 2004 were included in the present study. The histopathological findings of PD in Atlantic salmon and rainbow trout in sea water were similar. Acute PD, characterized by acute necrosis of exocrine pancreatic tissues, was detected in nine Atlantic salmon and three rainbow trout. Salmonid alphavirus (SAV) was identified in acute pancreatic necroses by immunohistochemistry. Most fish showed severe loss of exocrine pancreatic tissue combined with chronic myositis. Myocarditis was often but not consistently found. Kidneys from 40% and 64% of the rainbow trout and Atlantic salmon, respectively, had cells along the sinusoids that were packed with cytoplasmic eosinophilic granules. These cells resembled hypertrophied endothelial cells or elongated mast cell analogues. Histochemical staining properties and electron microscopy of these cells are presented. SAV was identified by RT-PCR and neutralizing antibodies against SAV were detected in blood samples.
Espen Rimstad - One of the best experts on this subject based on the ideXlab platform.
-
effect of a novel dna vaccine against Pancreas Disease caused by salmonid alphavirus subtype 3 in atlantic salmon salmo salar
Fish & Shellfish Immunology, 2021Co-Authors: Ragnar Thorarinsson, Jeffrey C Wolf, Makoto Inami, Lisa J Phillips, Ginny Jones, Alicia Macdonald, Jose Rodriguez, Hilde Sindre, Eystein Skjerve, Espen RimstadAbstract: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 degree 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 naive 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.
-
effect of a novel dna vaccine against Pancreas Disease caused by salmonid alphavirus subtype 3 in atlantic salmon salmo salar
Fish & Shellfish Immunology, 2021Co-Authors: Ragnar Thorarinsson, Jeffrey C Wolf, Makoto Inami, Lisa J Phillips, Ginny Jones, Alicia Macdonald, Jose Rodriguez, Hilde Sindre, Eystein Skjerve, Espen RimstadAbstract: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 naive 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.
-
Detection of specific Atlantic salmon antibodies against salmonid alphavirus using a bead-based immunoassay
Fish and Shellfish Immunology, 2020Co-Authors: Lena Hammerlund Teige, Hilde Sindre, Espen Rimstad, Jorunn B. Jørgensen, Bertrand Collet, Magnus Vikan Røsæg, Ingvill Jensen, Ida Aksnes, Catherine M. Collins, Maria Krudtaa DahleAbstract: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.
-
Experimental Piscine orthoreovirus infection mediates protection against Pancreas Disease in Atlantic salmon (Salmo salar)
Veterinary Research, 2016Co-Authors: Morten Lund, Espen Rimstad, Magnus Vikan Røsæg, Aleksei Krasnov, Gerrit Timmerhaus, Ingvild Berg Nyman, Vidar Aspehaug, Maria Krudtaa DahleAbstract:AbstractViral Diseases are among the main challenges in farming of Atlantic salmon (Salmo salar). The most prevalent viral Diseases in Norwegian salmon aquaculture are heart and skeletal muscle inflammation (HSMI) caused by Piscine orthoreovirus (PRV), and Pancreas Disease (PD) caused by Salmonid alphavirus (SAV). Both PRV and SAV target heart and skeletal muscles, but SAV additionally targets exocrine Pancreas. PRV and SAV are often present in the same locations and co-infections occur, but the effect of this crosstalk on Disease development has not been investigated. In the present experiment, the effect of a primary PRV infection on subsequent SAV infection was studied. Atlantic salmon were infected with PRV by cohabitation, followed by addition of SAV shedder fish 4 or 10 weeks after the initial PRV infection. Histopathological evaluation, monitoring of viral RNA levels and host gene expression analysis were used to assess Disease development. Significant reduction of SAV RNA levels and of PD specific histopathological changes were observed in the co-infected groups compared to fish infected by SAV only. A strong correlation was found between histopathological development and expression of Disease related genes in heart. In conclusion, experimentally PRV infected salmon are less susceptible to secondary SAV infection and development of PD.
-
salmonid alphavirus glycoprotein e2 requires low temperature and e1 for virion formation and induction of protective immunity
Vaccine, 2014Co-Authors: Mia C Hikke, Espen Rimstad, Stephane Villoing, Stine Braaen, Kjartan Hodneland, Corinne Geertsema, Lisa M Verhagen, Petter Frost, Just M Vlak, Gorben P PijlmanAbstract:Salmonid alphavirus (SAV; also known as Salmon Pancreas Disease virus; family Togaviridae) causes Pancreas Disease and sleeping Disease in Atlantic salmon and rainbow trout, respectively, and poses a major burden to the aquaculture industry. SAV infection in vivo is temperature-restricted and progeny virus is only produced at low temperatures (10–15 °C). Using engineered SAV replicons we show that viral RNA replication is not temperature-restricted suggesting that the viral structural proteins determine low-temperature dependency. The processing/trafficking of SAV glycoproteins E1 and E2 as a function of temperature was investigated via baculovirus vectors in Sf9 insect cells and by transfection of CHSE-214 fish cells with DNA constructs expressing E1 and E2. We identified SAV E2 as the temperature determinant by demonstrating that membrane trafficking and surface expression of E2 occurs only at low temperature and only in the presence of E1. Finally, a vaccination-challenge model in Atlantic salmon demonstrates the biological significance of our findings and shows that SAV replicon DNA vaccines encoding E2 elicit protective immunity only when E1 is co-expressed. This is the first study that identifies E2 as the critical determinant of SAV low-temperature dependent virion formation and defines the prerequisites for induction of a potent immune response in Atlantic salmon by DNA vaccination.
T Taksdal - One of the best experts on this subject based on the ideXlab platform.
-
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
Frontiers in Veterinary Science, 2019Co-Authors: Mona Dverdal Jansen, Edgar Brun, T Taksdal, H Sindre, Mario Guarracino, Marianne Carson, I Modahl, Saraya TavornpanichAbstract: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.
-
the epidemiology of Pancreas Disease in salmonid aquaculture a summary of the current state of knowledge
Journal of Fish Diseases, 2017Co-Authors: Mona Dverdal Jansen, M F Mcloughlin, D A Graham, H D Rodger, Britt Bang Jensen, T Taksdal, H Sindre, Atle LillehaugAbstract:Pancreas Disease (PD) is a viral Disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the Disease itself and to factors contributing to agent spread and Disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated Disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.
-
salmonid alphavirus sav and Pancreas Disease pd in atlantic salmon salmo salar l in freshwater and seawater sites in norway from 2006 to 2008
Journal of Fish Diseases, 2010Co-Authors: M D Jansen, Edgar Brun, T Taksdal, Anne Berit Olsen, M A Wasmuth, B Gjerset, O Breck, M SandbergAbstract:A cohort study was initiated in the spring of 2006 to investigate epidemiological aspects and pathogenesis of salmonid alphavirus (SAV) subtype 3 infections and Pancreas Disease (PD). The aims were to assess involvement of the freshwater production phase, the extent and frequency of subclinical infections and to follow PD-affected populations throughout the entire seawater production cycle, as well as investigate possible risk factors for PD outbreaks. Fish groups from 46 different Atlantic salmon freshwater sites in six counties were sampled once prior to seawater transfer and followed onto their seawater sites. A total of 51 Atlantic salmon seawater sites were included, and fish groups were sampled three times during the seawater production phase. SAV subtype 3 was not identified by real-time RT-PCR from samples collected in the freshwater phase, nor were any SAV-neutralizing antibodies or histopathological changes consistent with PD. In the seawater phase, SAV was detected in samples from 23 of 36 (63.9%) studied sites located within the endemic region. No SAV subtype 3 was detected in samples from seawater sites located outside the endemic region. The cumulative incidence of PD during the production cycle amongst sites with SAV detected was 87% (20 of 23 sites). Average fish weight at time of PD diagnosis ranged from 461 to 5978 g, because of a wide variation in the timing of Disease occurrence throughout the production cycle. Mortality levels following a PD diagnosis varied greatly between populations. The mean percentage mortality was 6.9% (+/-7.06) (range 0.7-26.9), while the mean duration of increased mortality following PD diagnosis was 2.8 months (+/-1.11) (range 1-6).
-
Pancreas Disease in farmed atlantic salmon salmo salar l and rainbow trout oncorhynchus mykiss walbaum in norway
Journal of Fish Diseases, 2007Co-Authors: D A Graham, T Taksdal, Anne Berit Olsen, I Bjerkas, M J Hjortaas, Birgit H Dannevig, M F McloughlinAbstract:The present paper describes, for the first time, clinical signs and pathological findings of Pancreas Disease (PD) in farmed Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in sea water in Norway. Similarities and differences with reports of PD from Ireland and Scotland are discussed. Samples of 68 rainbow trout from Disease outbreaks on 14 farms and from 155 Atlantic salmon from outbreaks on 20 farms collected from 1996 to 2004 were included in the present study. The histopathological findings of PD in Atlantic salmon and rainbow trout in sea water were similar. Acute PD, characterized by acute necrosis of exocrine pancreatic tissues, was detected in nine Atlantic salmon and three rainbow trout. Salmonid alphavirus (SAV) was identified in acute pancreatic necroses by immunohistochemistry. Most fish showed severe loss of exocrine pancreatic tissue combined with chronic myositis. Myocarditis was often but not consistently found. Kidneys from 40% and 64% of the rainbow trout and Atlantic salmon, respectively, had cells along the sinusoids that were packed with cytoplasmic eosinophilic granules. These cells resembled hypertrophied endothelial cells or elongated mast cell analogues. Histochemical staining properties and electron microscopy of these cells are presented. SAV was identified by RT-PCR and neutralizing antibodies against SAV were detected in blood samples.
D Todd - One of the best experts on this subject based on the ideXlab platform.
-
experimental infection of atlantic salmon salmo salar pre smolts by i p injection with new irish and norwegian salmonid alphavirus sav isolates a comparative study
Diseases of Aquatic Organisms, 2007Co-Authors: K E Christie, M F Mcloughlin, D A Graham, D Todd, Stephane Villoing, D KnappskogAbstract:Atlantic salmon Salmo salar L. pre-smolts were experimentally infected with 2 different isolates of salmonid alphavirus (SAV): a Subtype 1 isolate from Ireland and a Subtype 3 isolate from Norway. Sequential samples of tissue and blood were collected during a period of 20 wk post injection and subjected to virus isolation from kidney tissue and serum, detection of viral nucleic acid in heart tissue and serum by real-time RT-PCR, detection of specific antibodies by virus neutralisation assay, and histopathological examination. Successful reproduction of Pancreas Disease (PD) was obtained by intraperitoneal (i.p.) injection of both isolates. No mortality was observed post infection in either group, but typical PD histopathological lesions in heart and Pancreas tissue were observed with both isolates. The prevalence and severity of lesions in the Pancreas, heart, skeletal muscle and brain were similar in both groups with only subtle differences recorded. Re-isolation of virus from kidney tissue was performed at 7 and 14 d post infection (d p.i.) only and was positive for both test groups at both sampling points. Isolation of virus from sera from both groups was positive at 4 to 14 d p.i., but was negative at later sampling points when antibody production had begun. Virus may be detected only during the acute phase using both methods. Specific neutralising antibodies could be detected for both test groups from Day 21 p.i. until the end of the experiment at 140 d p.i. Peak antibody titres were seen 70 d p.i. Using real-time RT-PCR, Pancreas Disease virus (PDV)-specific RNA was detected frequently in serum samples up to 14 d p.i. and occasionally thereafter. In contrast, viral RNA could still be detected in the heart tissue of fish from both groups for at least 140 d p.i.
-
sub clinical infection of farmed atlantic salmon salmo salar with salmonid alphavirus a prospective longitudinal study
Diseases of Aquatic Organisms, 2006Co-Authors: D A Graham, M F Mcloughlin, H M Rowley, H Jewhurst, P Sourd, C Taylor, D ToddAbstract:A prospective longitudinal study of salmonid alphavirus infection in farmed Atlantic salmon Salmo salar L. was initiated in post-transfer smolts on a UK farm in July 2004 and continued for 320 d. Sampling was concentrated on a single caged population (C4) with serum and tissue samples collected and tested for viraemia, virus neutralising (VN) antibodies and viral nucleic acid by real time RT-PCR and by histopathology; 380 sera collected between Days 0 (DO) and 139 (D139) were consistently negative for both viraemia and VN antibodies. The first evidence of infection was detected on D146, when 4 out of 20 fish were found to be viraemic and 1 of 20 to be antibody-positive. On D153 only 2 of 20 fish was viraemic and 1 antibody positive. At the next sampling (D158) no viraemic or antibody positive fish were detected. Thereafter, one or two viraemic fish were detected on 6 occasions, including on D320. The prevalence of antibody-positive fish remained low (0 to 5%) until D192 after which time it rose irregularly to a peak of 57.9% on D320. Real time RT-PCR testing of sera was more sensitive than screening for viraemia, detecting a peak of 35 % positive on D153 before declining. Histological lesions diagnostic for Pancreas Disease (PD) were observed at D146 and D153 only. In addition, mild cardiac and to a lesser extent brain lesions were frequently found after virus was detected, but not in earlier samples. No clinical signs or mortalities attributable to PD occurred throughout the study. This is the first detailed report of sub-clinical infection and highlights the usefulness of longitudinal surveys and the detection of virus and antibodies as diagnostic and epidemiological tools.
-
virological serological and histopathological evaluation of fish strain susceptibility to experimental infection with salmonid alphavirus
Diseases of Aquatic Organisms, 2006Co-Authors: M F Mcloughlin, D A Graham, H M Rowley, H Jewhurst, A Norris, D Matthews, L Foyle, J Macphee, D ToddAbstract:Pancreas Disease (PD) of farmed Atlantic salmon Salmo salar L., which is caused by an alphavirus known as salmon Pancreas Disease virus (SPDV), can have serious economic consequences. An epidemiological survey carried out in Ireland in 2003 indicated that within individual farms there were significant differences in the susceptibility of different strains of farmed Atlantic salmon to infection with SPDV, as measured by levels of clinical Disease and mortality. The aim of this preliminary study was to investigate this field observation by comparing lesion development, viraemia and serological responses of 3 commercial strains of Atlantic salmon (A, B and C) experimentally infected with SPDV. Highly significant differences in the severity of lesions in the Pancreas at Day 21 post-infection (pi) were detected (p < 0.01), with Group B being more severely affected. There were also significant differences in the prevalence and severity of lesions in heart and skeletal muscle at Day 21 and 35 pi respectively, with Group B results again significantly higher than those from both Groups A and C (p < 0.05). There was no overlap between viraemia and the presence of specific SPDV antibody. Some fish in all groups had no viraemia, lesions or evidence of seroconversion. There were no significant differences seen between the challenged groups in relation to the percentage of viraemic fish at each time point. Viral loads were not determined. Differences between the number of antibody-positive fish in each challenge group were found at Days 28 and 35 pi (p < 0.1). Highly significant differences (p < 0.01) in the geometric mean titres of seropositive fish were detected at Day 28. These results, obtained using a challenge model, confirm that there are strain differences in the susceptibility to experimental SPDV infection in commercial farmed Atlantic salmon.
-
nucleotide sequence variation in salmonid alphaviruses from outbreaks of salmon Pancreas Disease and sleeping Disease
Diseases of Aquatic Organisms, 2005Co-Authors: Jonathan Weston, Victoria Jewhurst, H M Rowley, David Graham, E J Branson, I W Walker, H Jewhurst, D ToddAbstract:We compared 18 salmonid alphaviruses (SAV) including the reference F93-125 salmon Pancreas Disease virus (SPDV) and S49p sleeping Disease virus (SDV) isolates by nucleotide sequence analyses of regions within the E1, nsP4 and nsP3 genes, and found these to comprise 3 distinct groups, which we have designated Subtypes 1, 2 and 3: Subtype 1, which comprised SAVs with sequences closely similar to the reference SPDV isolate, included SAVs from Pancreas Disease (PD) outbreaks in farmed salmon in Ireland and Scotland over a 10 yr period; viruses from recent outbreaks of sleeping Disease (SD) in freshwater-reared trout farmed in England, Scotland and France were closely similar to and were grouped with the reference SDV isolate in Subtype 2; 3 viruses isolated from PD-affected salmon in Norway were genetically different from viruses belonging to Subtypes 1 and 2 and have been assigned to Subtype 3; 1 virus isolated from PD-affected salmon in the Western Isles, Scotland, in 2003 showed consistent nucleotide sequence differences from SAV Subtypes 1, 2 and 3, but was more closely related to the Subtype 1 SAVs. The occurrence of the different subtype SAVs appeared to have a geographical basis, which may prove useful in future molecular epidemiology studies of SAV-induced Disease outbreaks.
-
longitudinal serological surveys of atlantic salmon salmo salar l using a rapid immunoperoxidase based neutralization assay for salmonid alphavirus
Journal of Fish Diseases, 2005Co-Authors: D A Graham, M F Mcloughlin, Victoria Jewhurst, H M Rowley, H D Rodger, D ToddAbstract:Longitudinal serological surveys for salmon Pancreas Disease virus (SPDV), the causal agent of Pancreas Disease (PD), were conducted on multiple caged populations of Atlantic salmon, Salmo salar L., on two farms over a 77-week period (farm 1, freshwater and marine stages) and a 36-week period (farm 2, marine stage only), using a microtitre-based virus neutralization (VN) assay. Collected sera were also screened for viraemia with SPDV, and Pancreas, heart and muscle tissues were examined for lesions consistent with PD. Outbreaks of PD occurred during the marine phase on both farms, as demonstrated by seroconversion, the isolation of virus and progressive histopathological changes consistent with a PD outbreak. All populations monitored showed a progressive increase in seroprevalence of 90-100%, typically accompanied by rises in geometric mean antibody titres. With the exception of one caged population, which showed a marked biphasic seroprevalence pattern, the seroprevalence figures in the remaining four monitored populations remained high (> or =70%) until the end of the study period. Peak VN titres of > or =1/1280 were detected on both farms. The results provide essential baseline information for the interpretation of SPDV VN serology results, and indicate that this methodology is suited to both the diagnosis and seroepidemiology of SPDV infections.
