DAO 78:1-12 (2007)  -  DOI: https://doi.org/10.3354/dao01866

Morphologic description of infectious salmon anaemia virus (ISAV)-induced lesions in rainbow trout Oncorhynchus mykiss compared to Atlantic salmon Salmo salar

Christine MacWilliams1,3, Gerald Johnson1, David Groman2, Frederick S. B. Kibenge1,*

1Department of Pathology and Microbiology, and 2Aquatic Diagnostic Services, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island C1A 4P3, Canada
3Present address: Department of Fisheries and Oceans, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada
*Corresponding author. Email:

ABSTRACT: In the present study the pathogenesis of experimental infectious salmon anaemia virus (ISAV) infection in rainbow trout Oncorhynchus mykiss (Walbaum, 1972) and Atlantic salmon Salmo salar was compared. The virus infection in the 2 species demonstrated different mortality patterns and pathology characteristics. Atlantic salmon showed a typical acute mortality pattern peaking at 8 to 16 d post-infection (dpi) depending on virus dose, whereas in rainbow trout, only the highest virus dose (107.13–7.8 TCID50/200 µl) showed a similar pattern. The middle (104.13 TCID50/200 µl) and lowest virus doses (102.13 TCID50/200 µl) in rainbow trout induced only sporadic protracted mortality, lasting up to 46 dpi. Infected rainbow trout that were live-sampled and those that died demonstrated increased erythrophagia, clusters of cellular degeneration in the haematopoietic portion of the kidney, and occasionally epicarditis, endocarditis and myocarditis. These lesions are very different from the typical necrosis in liver and kidney that occur in infected Atlantic salmon, and some of them may be indicative of an antiviral response by a resistant host to the ISAV infection. Virus was detected in the endothelium of the rainbow trout tissues using in situ hybridization, supporting our conclusions of the ISAV-induced lesions in this report.


KEY WORDS: Infectious salmon anaemia virus · ISAV · Rainbow trout pathology · Host antiviral response


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Cite this article as: MacWilliams C, Johnson G, Groman D, Kibenge FSB (2007) Morphologic description of infectious salmon anaemia virus (ISAV)-induced lesions in rainbow trout Oncorhynchus mykiss compared to Atlantic salmon Salmo salar. Dis Aquat Org 78:1-12. https://doi.org/10.3354/dao01866

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