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Louboutin L, Cabon J, Beven V, Hirchaud E, Blanchard Y, Morin T. Characterization of a New Toti-like Virus in Sea Bass, Dicentrarchus labrax. Viruses 2023; 15:2423. [PMID: 38140664 PMCID: PMC10748352 DOI: 10.3390/v15122423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
The European sea bass Dicentrarchus labrax is the main species reared in Mediterranean aquaculture. Its larval stage, which is very sensitive and highly affected by sanitary and environmental conditions, is particularly scrutinized in hatcheries. Recently, a Mediterranean sea bass farm had to deal with an abnormal increase in mortality, especially between 20 and 35 days post-hatching (dph). Biological investigations led to the observation of cytopathic effects on three different fish cell lines after almost 3 weeks of culture at 14 °C in contact with homogenized affected larvae, suggesting the presence of a viral agent. High-throughput sequencing revealed a 6818-nucleotide-long RNA genome with six putative ORFs, corresponding to the organization of viruses belonging to the Totiviridae family. This genome clustered with the newly described and suggested Pistolvirus genus, sharing 45.5% to 37.2% nucleotide identity with other piscine toti-like viruses such as Cyclopterus lumpus toti-like virus (CLuTLV) or piscine myocarditis virus (PMCV), respectively. Therefore, we propose to name this new viral agent sea bass toti-like virus (SBTLV). Specific real-time RT-PCR confirmed the presence of the viral genome in the affected larval homogenate from different production batches and the corresponding cell culture supernatant. Experimental infections performed on sea bass fingerlings did not induce mortality, although the virus could be detected in various organs and a specific immune response was developed. Additional studies are needed to understand the exact involvement of this virus in the mortality observed in hatcheries and the potential associated cofactors.
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Affiliation(s)
- Lénaïg Louboutin
- Unité Virologie, Immunologie et Écotoxicologie des Poissons, Laboratoire de Ploufragan-Plouzané-Niort, National Infrastructure Emerg’In, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 29280 Plouzané, France; (L.L.); (J.C.)
| | - Joëlle Cabon
- Unité Virologie, Immunologie et Écotoxicologie des Poissons, Laboratoire de Ploufragan-Plouzané-Niort, National Infrastructure Emerg’In, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 29280 Plouzané, France; (L.L.); (J.C.)
| | - Véronique Beven
- Unité Génétique virale et biosécurité, Laboratoire de Ploufragan-Plouzané-Niort, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 22440 Ploufragan, France; (V.B.); (E.H.)
| | - Edouard Hirchaud
- Unité Génétique virale et biosécurité, Laboratoire de Ploufragan-Plouzané-Niort, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 22440 Ploufragan, France; (V.B.); (E.H.)
| | - Yannick Blanchard
- Unité Génétique virale et biosécurité, Laboratoire de Ploufragan-Plouzané-Niort, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 22440 Ploufragan, France; (V.B.); (E.H.)
| | - Thierry Morin
- Unité Virologie, Immunologie et Écotoxicologie des Poissons, Laboratoire de Ploufragan-Plouzané-Niort, National Infrastructure Emerg’In, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail (ANSES), 29280 Plouzané, France; (L.L.); (J.C.)
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Christiansen DH, Petersen PE, Dahl MM, Vest N, Aamelfot M, Kristoffersen AB, Jansen MD, Matejusova I, Gallagher MD, Jónsson G, Rodriguez E, Fosse JH, Falk K. No Evidence of the Vertical Transmission of Non-Virulent Infectious Salmon Anaemia Virus (ISAV-HPR0) in Farmed Atlantic Salmon. Viruses 2021; 13:v13122428. [PMID: 34960697 PMCID: PMC8708482 DOI: 10.3390/v13122428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022] Open
Abstract
The nonvirulent infectious salmon anaemia virus (ISAV-HPR0) is the putative progenitor for virulent-ISAV, and a potential risk factor for the development of infectious salmon anaemia (ISA). Understanding the transmission dynamics of ISAV-HPR0 is fundamental to proper management and mitigation strategies. Here, we demonstrate that ISAV-HPR0 causes prevalent and transient infections in all three production stages of Atlantic salmon in the Faroe Islands. Phylogenetic analysis of the haemagglutinin-esterase gene from 247 salmon showed a clear geographical structuring into two significantly distinct HPR0-subgroups, which were designated G2 and G4. Whereas G2 and G4 co-circulated in marine farms, Faroese broodfish were predominantly infected by G2, and smolt were predominantly infected by G4. This infection pattern was confirmed by our G2- and G4-specific RT-qPCR assays. Moreover, the HPR0 variants detected in Icelandic and Norwegian broodfish were never detected in the Faroe Islands, despite the extensive import of ova from both countries. Accordingly, the vertical transmission of HPR0 from broodfish to progeny is uncommon. Phylogenetic and statistical analysis suggest that HPR0 persists in the smolt farms as “house-strains”, and that new HPR0 variants are occasionally introduced from the marine environment, probably by HPR0-contaminated sea-spray. Thus, high biosecurity—including water and air intake—is required to avoid the introduction of pathogens to the smolt farms.
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Affiliation(s)
- Debes Hammershaimb Christiansen
- National Reference Laboratory for Fish and Animal Diseases, Faroese Food and Veterinary Authority, 110 Torshavn, Faroe Islands; (P.E.P.); (M.M.D.); (N.V.)
- Correspondence:
| | - Petra Elisabeth Petersen
- National Reference Laboratory for Fish and Animal Diseases, Faroese Food and Veterinary Authority, 110 Torshavn, Faroe Islands; (P.E.P.); (M.M.D.); (N.V.)
| | - Maria Marjunardóttir Dahl
- National Reference Laboratory for Fish and Animal Diseases, Faroese Food and Veterinary Authority, 110 Torshavn, Faroe Islands; (P.E.P.); (M.M.D.); (N.V.)
| | - Nicolina Vest
- National Reference Laboratory for Fish and Animal Diseases, Faroese Food and Veterinary Authority, 110 Torshavn, Faroe Islands; (P.E.P.); (M.M.D.); (N.V.)
| | - Maria Aamelfot
- Norwegian Veterinary Institute, 0454 Oslo, Norway; (M.A.); (A.B.K.); (M.D.J.); (J.H.F.); (K.F.)
| | | | - Mona Dverdal Jansen
- Norwegian Veterinary Institute, 0454 Oslo, Norway; (M.A.); (A.B.K.); (M.D.J.); (J.H.F.); (K.F.)
| | - Iveta Matejusova
- Marine Scotland Science, Marine Laboratory, Aberdeen AB11 9DB, UK;
| | - Michael D. Gallagher
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH8 9YL, UK;
| | - Gísli Jónsson
- Icelandic Food and Veterinary Authority, 220 Hafnarfjordur, Iceland;
| | | | - Johanna Hol Fosse
- Norwegian Veterinary Institute, 0454 Oslo, Norway; (M.A.); (A.B.K.); (M.D.J.); (J.H.F.); (K.F.)
| | - Knut Falk
- Norwegian Veterinary Institute, 0454 Oslo, Norway; (M.A.); (A.B.K.); (M.D.J.); (J.H.F.); (K.F.)
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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. J Fish Dis 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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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