Experimental transmission of cardiomyopathy syndrome (CMS) in Atlantic salmon Salmo salar

Cardiomyopathy syndrome (CMS) has been recorded in wild and farmed Atlantic salmon Salmo salar. Characteristic heart lesions primarily involving the myocardium are reported in natural outbreaks with associated mortality. To date, no experimental trials have reproduced these lesions in the laboratory. The present study reports on the first successful experimental transmission of CMS in Atlantic salmon in Scotland, with full development of the histological lesions that are described for the syndrome. Tissue homogenates of CMS-infected fish indicative of mild and severe lesions from Scottish and Norwegian natural outbreaks, respectively, were injected into naïve fish, and both induced heart lesions consistent with CMS. Lesion development was earlier and progression faster in the fish group receiving the Norwegian homogenate, but equivalent in both groups by the end time point of the experiment. The study demonstrated that the reported condition for both countries is identical, as evaluated through light microscopy, and that tissue homogenates from either mild or severely affected fish contain the transmissible agent. KEY WORDS: Cardiomyopathy syndrome · Atlantic salmon · TransmissionResale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS

Section: Discussionsupporting

confidence: 80%

Comparative experimental transmission of cardiomyopathy syndrome (CMS) in Atlantic salmon Salmo salar

Bruno

Noguera²

2009

“…These diseases were selected due to the large discrepancies between the observed pathology and mortality in marine already recognised that several pathogens are associated with gill diseases (A. Nylund et al 1998, 2009a,b, Kvellestad et al 2003, Draghi et al 2004, Fridell et al 2004, Todal et al 2004, Callahan et al 2005, Young et al 2007, Steinum et al 2008, and it has also proven difficult to perform challenge experiments with most of these agents. The other 3 diseases, PD, HSMI and CMS, are all associated with the presence of viruses , 2006, Vågenes et al 1999, Nylund 2001, Kongtorp et al 2004a, Bruno & Noguera 2009, Fritsvold et al 2009, Palacios et al 2010, but it is difficult, in challenge experiments, to reproduce both the mortality and all the pathological changes observed during outbreaks in farms. In the present study we present the pathogens that are associated with these diseases in Norwegian culture of salmonids with a special emphasis on the possible importance of Paranucleospora theridion.…”

Section: Discussionmentioning

confidence: 99%

“…CMS occurs most often during the last 6 mo before termination of the sea production, i.e. during the second year at sea (Bruno & Noguera 2009, Fritsvold et al 2009). It is believed that CMS is caused by viruses , Vå-genes et al 1999, Nylund 2001, Bruno & Noguera 2009, Fritsvold et al 2009.…”

mentioning

confidence: 99%

Diseases of farmed Atlantic salmon Salmo salar associated with infections by the microsporidian Paranucleospora theridion

Nylund¹,

Andersen²,

Sævareid³

et al. 2011

The microsporidian Paranucleospora theridion was discovered in Atlantic salmon Salmo salar suffering from proliferative gill disease in a marine farm in western Norway in 2008. The parasite develops in cells of the reticuloendothelial system, cells important for normal immune function. The aim of this study was to see if P. theridion could play a part in some of the diseases with unclear causes in salmon production in Norway, i.e. proliferative gill disease (PGI), pancreas disease (PD), heart and skeletal muscle inflammation (HSMI) and cardiomyopathy syndrome (CMS). P. theridion was present in all areas with salmon farming in Norway, but high prevalence and densities of the parasite in salmon and salmon lice were only seen in southern Norway. This region is also the main area for PGI and PD in Norway. Quantification of pathogens associated with PGI, PD, HSMI and CMS diagnoses showed that P. theridion levels are high in southern Norway, and may therefore play a role in susceptibility and disease development. However, among the different diagnoses, fish with PGI are particularly heavily infected with P. theridion. Therefore, P. theridion appears as a possible primary agent in cases with high mortality in connection with PGI in western Norway. KEY WORDS: Paranucleospora theridion · Atlantic salmon · Microsporidia · Proliferative gill disease · PGI · Pancreas disease · PD Resale or republication not permitted without written consent of the publisherDis Aquat Org 94: [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] 2011 Clavochlamydia salmonicola , Atlantic salmon paramyxovirus (Kvellestad et al. 2005), and salmon gill poxvirus . These agents may all contribute to the gill pathology, hypertrophia, hyperplasia, inflammation and necrosis of gill tissues, but it is not known whether they are primary pathogens or secondary invaders.It is well documented that 'pancreas disease' is associated with the presence of different strains of SAV (Nelson et al. 1995, McLoughlin et al. 1996, Villoing et al. 2000, Hodneland et al. 2005, Fringuelli et al. 2008). However, the observed disease and mortality in salmon and rainbow trout farms are different from what can be seen in challenge experiments using the different SAV strains . The explanations for this could be presence of different pathogens or other stress factors that may trigger the disease or be the primary cause of disease, reducing SAV to a secondary cause of the observed mortality in farms. Lack of comparable mortality and to a certain extent also pathology has also been observed when comparing challenge experiments using CMS and HSMI homogenates with the observed situation in salmon farms affected by these 2 diseases (Kongtorp et al. 2004a, Fritsvold et al. 2009. Hence, the trigger or primary causes for these diseases could be environmental factors or other pathogens.Paranucleospora theridion was first discovered in farmed Atlantic salmon suffering from gill disease in western Norway in (A. Nylund et al. 2009a,b, S. Nylund et al. 2009. Th...

“…This was based on the presence of eosinophilic inclusions in nuclei of myocardial fibres in the vicinity of degenerated areas. Experimental transmission studies have supported this hypothesis (Bruno & Noguera 2009, Fritsvold et al 2009, and in 2010 a doublestranded RNA virus tentatively of the Totiviridae family was described as the causative agent of CMS (Løvoll et al 2010, Haugland et al 2011.…”

Section: Introductionmentioning

confidence: 78%

“…The CMS diagnosis has so far been based on detection of characteristic inflammation and degeneration of spongy myocardium in the atrium and ventricle during histopathological examination. Secondary findings are multifocal liver necrosis, indicative of chronic passive congestive circulatory disturbances (Amin & Trasti 1988, Ferguson et al 1990, Fritsvold et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Piscine myocarditis virus (PMCV) in wild Atlantic salmon Salmo salar

Garseth

Biering²,

Tengs³

2012

Cardiomyopathy syndrome (CMS) is a severe cardiac disease of sea-farmed Atlantic salmon Salmo salar L., but CMS-like lesions have also been found in wild Atlantic salmon. In 2010 a double-stranded RNA virus of the Totiviridae family, provisionally named piscine myocarditis virus (PMCV), was described as the causative agent of CMS. In the present paper we report the first detection of PMCV in wild Atlantic salmon. The study is based on screening of 797 wild Atlantic salmon by real-time RT-PCR. The samples were collected from 35 different rivers along the coast of Norway, and all individuals included in the study were classified as wild, based on visual appearance and scale reading. Two samples tested positive during PCR analysis, and the results were confirmed by sequencing. KEY WORDS: Piscine myocarditis virus · Wild Atlantic salmon · PCR · CMS · Disease interactionResale or republication not permitted without written consent of the publisher OPEN PEN