ABSTRACT: Since 2012, an orthomyxo-like virus has been consistently linked to epizootics in marine farmed Atlantic salmon in Tasmania, Australia. Here we describe the properties of the virus, designated the pilchard orthomyxovirus (POMV), in cell culture and present data verifying its direct role in a disease of Atlantic salmon. In infected cells, viral RNA was detectable in both the nucleus and cytoplasm, consistent with the replication cycle of an orthomyxovirus. Viral replication in vitro was temperature-dependent (within a range of 10-20°C), and yields of virus were typically in excess of 10⁷ TCID₅₀ ml^-1. In controlled infection trials, cell culture-derived POMV produced significant morbidity in Atlantic salmon fry, pre-smolt and post-smolt. In all cases, the development of disease was rapid, with moribund fish detected within 5 d of direct exposure to POMV, and maximum cumulative morbidity occurring within 4 wk. The experimentally infected fish developed a characteristic suite of gross and microscopic pathological changes, which were consistent with those observed in Atlantic salmon overtly affected by POMV-associated disease on sea farms. These included necrotic lesions across multiple organs that were directly associated with the presence of the virus. Together, our observations indicate that POMV is an endemic virus likely transmitted from wild fish to farmed Atlantic salmon in Tasmania. The virus is pathogenic to Atlantic salmon in freshwater and marine environments and causes a disease that we have named salmon orthomyxoviral necrosis.

中文翻译：

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Pilchard正粘病毒（POMV）。二。鲑鱼正粘病毒坏死的病原体，是大西洋鲑鲑鱼Salmo salar的新病。

摘要：自2012年以来，在澳大利亚塔斯马尼亚州海洋养殖的大西洋鲑鱼中，类正粘病毒一直与流行病相关。在这里，我们描述了在细胞培养中命名为沙丁病毒（POMV）的正痘病毒的特性，并提供了证实其在大西洋鲑鱼疾病中直接作用的数据。在感染的细胞中，在细胞核和细胞质中均可检测到病毒RNA，与正粘病毒的复制周期一致。体外病毒复制是温度依赖性的（在10-20°C范围内），病毒的产量通常超过10 ⁷ TCID ₅₀ ml ^-1。在对照感染试验中，源自细胞培养物的POMV在大西洋鲑鱼苗，熏鲑前和熏鲑后产生了明显的发病率。在所有情况下，疾病的发展都是迅速的，在直接暴露于POMV后5天内检测到垂死的鱼，最大累积发病率在4周内发生。经实验感染的鱼出现了特征性的总体和微观病理变化，这与在海水养殖场中受POMV相关疾病影响的大西洋鲑鱼中观察到的一致。这些包括跨多个器官的坏死性病变，这些病变与病毒的存在直接相关。总之，我们的观察表明POMV是一种地方性病毒，很可能从野生鱼传播到塔斯马尼亚州养殖的大西洋鲑鱼。