Piscine Orthoreovirus, is a segmented virus, non-enveloped RNA, 60 – 80 µm, with icosahedral shape, belonging to the family Reoviridae, subfamily Spinareovirinae and is the aetiological agent of Heart and Skeletal Muscle Inflammation (HSMI).
The HSMI disease is diagnosed by the occurrence of histopathologic lesions in the heart and skeletal muscle; moderate to severe panmyocarditis (inflammation in the compact and spongy layers of the myocardium); and myocardial degeneration and necrosis.
The skeletal muscle also shows moderate to severe myodegeneration and necrosis, especially of the red muscle fibres, as well as inflammation.
Lesions in the skeletal muscle tend to occur mostly during the peak of the outbreak and, to a lesser extent, in the recovery phase. Histopathological lesions in other organs include liver necrosis and congestion, haemorrhages in liver, kidney, spleen and gills.
REFERENCES
- Carstens, E. B., and Ball, L. A. 2009. Ratification vote on taxonomic proposal to the International Committee on Taxonomy of Viruses. Archives of Virology, 154:1181–1188.
- Di Cicco, E., Ferguson, H. W., Schulze, A. D., Kaukinen, K. H., Li, S., Vanderstichel, R., … & Miller, K. M. (2017). Heart and skeletal muscle inflammation (HSMI) disease diagnosed on a British Columbia salmon farm through a longitudinal farm study. PLoS One, 12(2).
- Kongtorp, R. T., Kjerstad, A., Taksdal, T., Guttvik, A., & Falk, K. (2004). Heart and skeletal muscle inflammation in Atlantic salmon, Salmo salar L.: a new infectious disease. Journal of Fish Diseases, 27(6), 351-358.
- Kongtorp, R. T., Halse, M., Taksdal, T., & Falk, K. (2006). Longitudinal study of a natural outbreak of heart and skeletal muscle inflammation in Atlantic salmon, Salmo salar L. Journal of Fish Diseases, 29(4), 233-244.
