DAO 126:43-50 (2017)  -  DOI: https://doi.org/10.3354/dao03159

High nervous necrosis virus (NNV) diversity in wild wrasse (Labridae) in Norway and Sweden

Kjetil Korsnes1,2,*, Egil Karlsbakk3,4, Cecilie K. Skår3, Lisbeth Sælemyr3, Are Nylund4, Bjørn Olav Kvamme3, Stein Mortensen3

1Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway
2BioVivo Technologies AS, 8029 Bodø, Norway
3Institute of Marine Research, Nordnesgaten 50, 5817 Bergen, Norway
4Institute of Biology, University of Bergen, Thormøhlensgate 55, 5020 Bergen, Norway
*Corresponding author:

ABSTRACT: Wild goldsinny wrasse Ctenolabrus rupestris, corkwing wrasse Symphodus melops and ballan wrasse Labrus bergylta were collected at 8 sampling sites in Sweden and Norway during summer 2014. Brain tissue from 466 wrasses were analyzed for nervous necrosis virus (NNV) infections by real-time RT-PCR, and positive samples were subjected to sequencing and phylogenetic analysis of partial segments of the RNA2 and RNA1 genes. This study shows that NNV is present in wild ballan, corkwing and goldsinny wrasse along the coastline of Sweden and Norway. The overall prevalence in the sampled labrids was 6.7%. Prevalence was 6.4% in goldsinny, 6.3% in corkwing and 18% in ballan wrasse. The wrasse RNA2 NNV sequences revealed high genetic variability and were divided into 3 clusters within the cold water barfin flounder NNV (BFNNV) and warm water cluster red-spotted grouper NNV (RGNNV) genogroups. Within the BFNNV genogroup, wrasse NNVs clustered in 2 sub-genogroups, with grey mullet NNV (GMNNV) and with Atlantic halibut NNV (AHNNV). These groups were previously dominated by virus originating from Atlantic cod Gadus morhua and Atlantic halibut Hippoglossus hippoglossus from the northeast Atlantic. The presence of NNV in wild wrasse and the surprising high genetic variability observed in this study should be considered before moving wild-caught wrasse between geographically distant sites. The results show that use of wild-caught wrasse as brood fish in wrasse farming represents a risk of introducing NNV into aquaculture.


KEY WORDS: Betanodavirus · Wild marine fish · NNV · Genotypes · Wrasse


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Cite this article as: Korsnes K, Karlsbakk E, Skår CK, Sælemyr L, Nylund A, Kvamme BO, Mortensen S (2017) High nervous necrosis virus (NNV) diversity in wild wrasse (Labridae) in Norway and Sweden. Dis Aquat Org 126:43-50. https://doi.org/10.3354/dao03159

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