Characterization of nodavirus and viral encephalopathy and retinopathy in farmed turbot, Scophthalmus maximus (L.)

Journal of Fish Diseases - Tập 27 Số 10 - Trang 591-601 - 2004
Rebecca E. Blanton1, Ingunn Sommerset2, Brit Tørud3, Kjetil Korsnes4,2, M J Hjortaas1, Frank Nilsen2, Audun Helge Nerland2, Birgit H. Dannevig1
1National Veterinary Institute, Oslo, Norway
2Institute of Marine Research, Nordnes, Bergen, Norway
3Veterinary Service in Aquaculture, Valsøyfjord, Norway
4Bodø Regional University, Bodø, Norway

Tóm tắt

AbstractAn outbreak of nodavirus infection in turbot larvae is described with respect to histopathology, immunohistochemistry, cell culture cultivation, RT‐PCR amplification and sequence analysis of the capsid protein gene RNA2. Affected turbot developed classical signs of viral encephalopathy and retinopathy (VER) with abnormal swimming behaviour and high mortality levels. In the acute stage of infection, light microscopy revealed vacuolation of the central nervous system (CNS), with positive immunohistochemical staining for nodavirus. Later in the infection, CNS lesions appeared more chronic and contained clusters of cells immunopositive for nodavirus. Bacterial overgrowth in the intestines of the fish may have provoked or influenced the course of the nodavirus infection. We were unable to propagate the virus in cell culture. While RT‐PCR using primers designed to detect Atlantic halibut nodavirus gave negative results, further testing with primers complementary to a more conserved region of RNA2 resulted in amplification of a product of the expected size. The entire RNA2 segment was cloned and sequenced. Sequence alignment showed that the turbot nodavirus (TNV) was different from previously described fish nodaviruses. In addition, phylogenetic analysis based on an 823 nt region of the sequence indicated that TNV clustered outside the four established fish nodavirus genotypes, suggesting a fifth genotype within the betanodaviruses.

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Thông tin xuất bản

Journal of Fish Diseases

Tập 27 Số 10

591-601

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