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

Niccoló Vendramin (1) , Dhamotharan Kannimuthu , Anne Berit Olsen , Argelia Cuenca , Lena Hammerlund Teige , Øystein Wessel , Tine Moesgaard Iburg , Maria Krudtaa Dahle , Espen Rimstad , Niels Jørgen Olesen

1 DTU - Danmarks Tekniske Universitet = Technical University of Denmark

AbstractPiscine 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.

Domaines: Sciences du Vivant [q-bio]

Niccoló Vendramin, Dhamotharan Kannimuthu, Anne Berit Olsen, Argelia Cuenca, Lena Hammerlund Teige, et al.. Piscine orthoreovirus subtype 3 (PRV-3) causes heart inflammation in rainbow trout (Oncorhynchus mykiss). Veterinary Research, 2019, 50 (1), pp.14. ⟨10.1186/s13567-019-0632-4⟩. ⟨hal-02488837⟩