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.

中文翻译：

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大西洋鲑（Salmo salar）中的沙丁鱼正粘病毒（POMV）在海水中的传播和感染动态。

塔斯马尼亚鲑鱼产业一直没有重大病毒性疾病，直到沙丁鱼正粘病毒（POMV）出现。POMV最初是从野生沙丁鱼中分离出来的，因此它引起了养殖鲑鱼（Salmo salar）的高死亡率，因此引起了业界的关注。）。野外观察表明，这种病毒可以在猪圈之间传播，也可以在养殖场之间传播，但尚不清楚海水中被动传播的证据。我们的目的是确定是否需要在感染和未加工的鱼之间进行直接接触以进行传播，并研究病毒感染的动态。通过同居直接暴露或通过病毒污染的海水间接暴露，大西洋鲑鲑的后熏鲑受到POMV的挑战。POMV可在海水中传播，并且感染之间不需要鱼之间的直接接触。在感染的早期阶段，头部肾脏和心脏呈现出最高的病毒载量。POMV幸存者在大多数组织中表现出较低的病毒载量，但g中的病毒载量仍然相对较高。一致的特征是病毒感染的黑色素巨噬细胞在不同组织中的浸润，提示了这些在POMV免疫反应中的重要作用。了解POMV传播和宿主-病原体相互作用是开发改进的监测工具，传播模型以及最终预防疾病的关键。