Comparison of transcriptome responses in blood cells of Atlantic salmon infected with three different genotypes of Piscine orthoreovirus

Piscine orthoreovirus (PRV) infection is a common threat in salmonid aquaculture. Three PRV variants (PRV-1-3) show host species specificity and cause different diseases in salmonids. All PRV variants infect and replicate in red blood cells (RBCs) in the early acute phase of infection. PRV-1 is the causative agent of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar), PRV-2 causes erythrocytic inclusion body syndrome (EIBS) in coho salmon (Oncorhynchus kisutch), while PRV-3 induces HSMI-like disease in farmed rainbow trout (Oncorhynchus mykiss). PRV-3 can also infect A. salmon without causing clinical disease, and has been shown to completely cross-protect against PRV-1 infection and HSMI, while injection of PRV-2 or an inactivated adjuvanted PRV-1 (InPRV-1) vaccine only partially protected, by reducing HSMI pathology. In the present work, we compare the transcriptome responses in blood cells of Atlantic salmon two and five weeks post infection with PRV-1, PRV-2, PRV-3, or post injection with an inactivated PRV-1 vaccine (InPRV-1), with uninfected control fish.