Molecular detection and characterization of nodavirus in several marine fish species from the northeastern Atlantic

[摘要] ABSTRACT: Nodaviruses (NNV) are responsible for causing disease outbreaks mainly in hatchery-reared larvae and juveniles of a wide variety of fishes throughout the world. This disease has seriously limited the culture of marine fishes over the lastdecade. In the Atlantic provinces of Canada, disease caused by a nodavirus was first reported in juvenile Atlantic cod being reared in Nova Scotia, in 1999. More recently, disease outbreaks caused by nodavirus have been identified in hatchery-rearedAtlantic cod and haddock in Newfoundland and New Brunswick, respectively, and along the east coast of the USA. The presence of NNV in wild Atlantic cod adults and wild winter flounder has also been reported. Nodaviruses were isolated from culturedAtlantic cod and haddock, as well as from wild winter flounder from a variety of geographical localities, and their virus coat (capsid) protein genes were partially sequenced. An analysis of the data indicates that all of the nodaviruses isolated fromeastern North America were closely related to one another, but that they were distinct from the European isolates already sequenced. Regardless of host species, isolates from close geographical localities were more similar than those from distantgeographical areas. At the protein level, differences in coat protein sequences were seen only for strains isolated from Atlantic cod originating from Newfoundland. Our results suggest that NNV may have been present in the Atlantic off Canada and on theeast coast of the USA for some time, and has evolved to form a monophyletic group, distinct from other isolates found in cold-water species. Non-lethal methods for detection of NNV are necessary to develop management strategies for this disease, and wouldbe an asset to diagnosticians and producers. Based on the results of this study, new primers were designed and developed for an improved RT-PCR assay able to detect North Atlantic nodaviruses in ovarian fluids, eggs and other tissues. The application ofthis test to field samples is discussed.

[学科分类] 生物科学（综合）

[关键词] Nodaviruses;RT-PCR;Phylogenetic analysis;Atlantic cod;Haddock