New clade of betanodaviruses detected in wild and farmed cod (Gadus morhua) in Norway
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Betanodaviruses have been isolated and detected in both farmed and wild fish species worldwide. They are classified in five clusters, and all are connected to mortalities in farmed fish. The clusters do not represent specific geographical areas or host species, but one cluster, barfin flounder nervous necrosis virus (BFNNV), is mainly associated with cold water fish species. This study presents the first species-specific clade within the BFNNV cluster. This clade consists of six isolates from wild and farmed Atlantic cod in Norway and is genetically distinct from other betanodaviruses in the North Atlantic. Screening of farmed and wild cod in Norway shows that betanodaviruses are present in wild fish on the west coast of Norway, including migratory cod, but so far we have not detected any betanodavirus-positive wild cod in northern Norway. The presence of significant amounts of betanodaviruses in wild cod represents a serious challenge for the management of viral nervous necrosis in farmed cod in Norway. Betanodavirus-positive farmed cod were present both in western and northern Norway. Mortalities in three cod farms were suspected to be caused by betanodaviruses; however, in two of these, other pathogens may have been responsible for or strongly contributed to the mortalities.
KeywordsKidney Tissue Nervous Necrosis Virus Vibrio Bacterium Striped Jack Nervous Necrosis Virus Brood Fish
This study was financed by the Norwegian Research Council (NFR 172533/S40) and by Hordland Fylkeskommune.
- 1.Arimoto M, Mushiake K, Mizuta Y, Nakai T, Muroga K, Furusawa I (1992) Detection of striped jack nervous necrosis virus (SJNNV) by enzyme-linked immunosorbent assay (ELISA). Gyobyo Kenkyu 27(4):191–195Google Scholar
- 2.Aspehaug V, Devold M, Nylund A (1999) The phylogenetic relationship of nervous necrosis virus from halibut (Hippoglossus hippoglossus). Bull Eur Assoc Fish Pathol 19:196–202Google Scholar
- 4.Breuil G, Pepin JF, Castric J, Fauvel C, Thiery R (2000) Detection of serum antibodies against nodavirus in wild and farmed adult sea bass: application to the screening of broodstock in sea bass hatcheries. Bull Eur Assoc Fish Pathol 20:95–100Google Scholar
- 6.Cusack RR, MacKinnon AM, Boston L, Peach R, Groman D (2002) Experimental exposure of juvenile Atlantic cod, haddock and Atlantic halibut to nodavirus isolated from Atlantic cod and haddock and the effects of cross-infectivety. In: Harrington KS (ed) Proceedings of the 4th international symposium on aquatic animal health. American Fisheries Society, New OrleansGoogle Scholar
- 10.Fukuda Y, Nguyen HD, Furuhasi M, Nakai T (1996) Mass mortality of cultured sevenband grouper, Epinephelus septemfasciatus, associated with viral nervous necrosis. Fish Pathol 31(3):165–170Google Scholar
- 18.Knipe DM, Howley PM (2001) Fields virology. Lippincott Williams and Wilkins, PhiladelphiaGoogle Scholar
- 23.Mushiake K, Nishizawa T, Nakai T, Furusawa I, Muroga K (1994) Control of VNN in striped jack: selection of spawners based on the detection of SJNNV gene by polymerase chain reaction (PCR). Fish Pathol 29(3):177–182Google Scholar
- 24.Nylund A, Karlsbakk E, Andersen L, Nylund S, Isaksen TE, Ottem KF, Handeland S (2006a) Nodaviruses are common in marine fish (in Norwegian). Norsk Fiskeoppdrett 10:52–54Google Scholar
- 29.Ottem KF, Nylund A, Karlsbakk E, Isaksen TE, Bergh Ø (2007) Occurrence of Francisella piscicida in farmed and wild Atlantic cod Gadus morhua L. in Norway. J Fish Dis (in press)Google Scholar
- 35.Swofford DL (1998) Phylogenetic analysis using parsimony and other methods, version 4.0. Sinauer Associates, SunderlandGoogle Scholar