National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark.
Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.
Vet Res. 2019 Feb 18;50(1):14. doi: 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.
鱼类正呼肠孤病毒（PRV）介导的疾病在鲑鱼养殖业中不断出现。目前有三种 PRV 亚型被报道为不同鲑鱼物种疾病的病原体或与之相关。PRV-1 可引起大西洋鲑（Salmo salar）的心肌和骨骼肌炎症（HSMI），并与养殖虹鳟（Oncorhynchus tshawytscha）的黄疸综合征有关。PRV-2 可引起日本养殖的银鲑（Oncorhynchus kisutch）的红细胞包涵体综合征（EIBS）。PRV-3 最近与虹鳟（Oncorhynchus mykiss）的一种疾病相关，其特征为贫血、心肌和红肌病理学；与养殖的银鲑（Oncorhynchus kisutch）的黄疸综合征有关。在本研究中，我们对虹鳟进行了为期 10 周的 PRV-3 纯化颗粒的实验性感染试验，以评估病毒与心肌炎症发展之间的因果关系。通过 RT-qPCR 监测心脏和脾脏中的 PRV-3 负荷显示病毒 RNA 逐渐增加至峰值，随后清除，而血细胞比容无明显变化。在试验后期出现特征性的心脏组织病理学发现，并伴有 CD8+表达增加，表明细胞毒性 T 细胞增殖。这些发现表明，在这些实验条件下，虹鳟中的 PRV-3 感染与大西洋鲑中的 PRV-1 感染在免疫反应和心脏病理学发展方面相似，但在建立持续性感染方面不同。
