CSIRO Agriculture and Food, Livestock and Aquaculture Program, Hobart, Tas., Australia.
Department of Biological Sciences, University of Bergen, Bergen, Norway.
J Fish Dis. 2021 Jan;44(1):73-88. doi: 10.1111/jfd.13269. Epub 2020 Sep 17.
The Tasmanian salmon industry had remained relatively free of major viral diseases until the emergence of pilchard orthomyxovirus (POMV). Originally isolated from wild pilchards, POMV is of concern to the industry as it can cause high mortality in farmed salmon (Salmo salar). Field observations suggest the virus can spread from pen to pen and between farms, but evidence of passive transmission in sea water was unclear. Our aim was to establish whether direct contact between infected and naïve fish was required for transmission, and to examine viral infection dynamics. Atlantic salmon post-smolts were challenged with POMV by either direct exposure via cohabitation or indirect exposure via virus-contaminated sea water. POMV was transmissible in sea water and direct contact between fish was not required for infection. Head kidney and heart presented the highest viral loads in early stages of infection. POMV survivors presented low viral loads in most tissues, but these remained relatively high in gills. A consistent feature was the infiltration of viral-infected melanomacrophages in different tissues, suggesting an important role of these in the immune response to POMV. Understanding POMV transmission and host-pathogen interactions is key for the development of improved surveillance tools, transmission models and ultimately for disease prevention.
塔斯马尼亚鲑鱼产业在原发性造血器官坏死病毒（POMV）出现之前，一直相对没有受到重大病毒性疾病的影响。POMV 最初从野生鲱鱼中分离出来，由于它会导致养殖鲑鱼（大西洋鲑）高死亡率，因此引起了业界的关注。实地观察表明，该病毒可以在养殖场之间以及从一个养殖场传播到另一个养殖场，但在海水中是否存在被动传播的证据尚不清楚。我们的目的是确定感染鱼和未感染鱼之间是否需要直接接触才能进行传播，并研究病毒感染的动态。通过共同养殖或通过受病毒污染的海水进行间接暴露，将 POMV 感染的大西洋鲑鱼苗幼鱼作为挑战。POMV 可以在海水中传播，并且感染不需要鱼类之间的直接接触。在感染的早期阶段，头肾和心脏呈现出最高的病毒载量。POMV 幸存者在大多数组织中的病毒载量较低，但在鳃中的病毒载量仍然相对较高。一个一致的特征是，不同组织中存在受病毒感染的黑色素巨噬细胞浸润，这表明这些细胞在对 POMV 的免疫反应中起着重要作用。了解 POMV 的传播和宿主-病原体相互作用对于开发改进的监测工具、传播模型以及最终预防疾病至关重要。
