Piscine orthoreovirus subtype 3 (PRV-3) causes heart inflammation in rainbow trout (Oncorhynchus mykiss)

• Published in: Veterinary Research
• Main Authors: Vendramin, Niccoló, Kannimuthu, Dhamotharan, Olsen, Anne Berit, Cuenca, Argelia, Teige, Lena Hammerlund, Wessel, Øystein, Iburg, Tine Moesgaard, Dahle, Maria Krudtaa, Rimstad, Espen, Olesen, Niels Jørgen
• Format: Text
• Language: English
• Published: BioMed Central 2019
• Subjects: Research Article; Atlantic salmon; Salmo salar
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6380033/; http://www.ncbi.nlm.nih.gov/pubmed/30777130; https://doi.org/10.1186/s13567-019-0632-4

Piscine orthoreovirus (PRV) mediated diseases have emerged throughout salmonid aquaculture. Three PRV subtypes are currently reported as causative agents of or in association with diseases in different salmonid species. PRV-1 causes heart and skeletal muscle inflammation (HSMI) in Atlantic salmon (Salmo salar) and is associated with jaundice syndrome in farmed chinook salmon (Oncorhynchus tshawytscha). PRV-2 causes erythrocytic inclusion body syndrome (EIBS) in coho salmon in Japan. PRV-3 has recently been associated with a disease in rainbow trout (Oncorhynchus mykiss) characterized by anaemia, heart and red muscle pathology; to jaundice syndrome in coho salmon (Oncorhynchus kisutch). In this study, we conducted a 10-week long experimental infection trial in rainbow trout with purified PRV-3 particles to assess the causal relationship between the virus and development of heart inflammation. The monitoring the PRV-3 load in heart and spleen by RT-qPCR shows a progressive increase of viral RNA to a peak, followed by clearance without a measurable change in haematocrit. The development of characteristic cardiac histopathological findings occurred in the late phase of the trial and was associated with increased expression of CD8+, indicating cytotoxic T cell proliferation. The findings indicate that, under these experimental conditions, PRV-3 infection in rainbow trout act similarly to PRV-1 infection in Atlantic salmon with regards to immunological responses and development of heart pathology, but not in the ability to establish a persistent infection. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13567-019-0632-4) contains supplementary material, which is available to authorized users.