Dahl Maria Marjunardóttir, Petersen Petra Elisabeth, Christiansen Debes Hammershaimb
Faroese Food and Veterinary Authority, National Reference Laboratory for Fish and Animal Diseases, V.U. Hammershaimbsgøta 11, Tórshavn, Faroe Islands.
J Gen Virol. 2025 Feb;106(2). doi: 10.1099/jgv.0.002068.
Piscine myocarditis virus (PMCV) is the causative agent of cardiomyopathy syndrome (CMS), a significant disease in farmed Atlantic salmon ( L.). Although an increasing number of CMS outbreaks have been recorded in the Faroe Islands since the reemergence of CMS in 2013, overall PMCV genetic diversity, transmission pathways and evolutionary trajectories remain elusive. Here, we present a fast amplicon-based whole-genome sequencing method of PMCV directly from field samples and disclose 48 novel genomes, adding to the single genome currently available. Phylogenetic analysis revealed that genomes with a broad spatiotemporal representation of Faroese farmed salmon formed a homogenous monophyletic cluster compared to Norwegian and Irish PMCV genomes. Homogeneity of the Faroese genomes was substantiated with principal component analyses, where no spatiotemporal clustering of genotypes was found, nor any clustering based on roe or smolt origin. One genome from a returning wild salmon differed considerably from all the rest and formed an outgroup. All three ORFs exhibited signs of purifying selection, although ORF3 displayed a comparatively lower degree of selective constraint. Furthermore, no virulence-determining amino acid substitutions were identified in the Faroese genomes as no association was found between CMS cases and specific amino acid substitutions or motifs. Our data suggest that PMCV was introduced into the Faroe Islands from Norway, where brood fish is known to be infected. However, despite a steadily increasing import of Norwegian roe, our results show no continuous reintroduction of persisting PMCV strains to Faroese farmed salmon.
鲤心肌炎病毒（PMCV）是心肌病综合征（CMS）的病原体，这是养殖大西洋鲑（L.）中的一种重要疾病。自2013年CMS再次出现以来，法罗群岛记录的CMS疫情越来越多，但PMCV的整体遗传多样性、传播途径和进化轨迹仍然难以捉摸。在这里，我们提出了一种基于快速扩增子的直接从野外样本中对PMCV进行全基因组测序的方法，并公布了48个新基因组，增加了目前仅有的一个基因组。系统发育分析表明，与挪威和爱尔兰的PMCV基因组相比，具有法罗群岛养殖鲑鱼广泛时空代表性的基因组形成了一个同质的单系群。法罗群岛基因组的同质性通过主成分分析得到证实，其中未发现基因型的时空聚类，也未发现基于鱼卵或幼鲑来源的聚类。一条返回的野生鲑鱼的一个基因组与其他所有基因组有很大差异，并形成了一个外类群。所有三个开放阅读框都表现出纯化选择的迹象，尽管开放阅读框3显示出相对较低程度的选择限制。此外，在法罗群岛的基因组中未发现决定毒力的氨基酸替换，因为在CMS病例与特定氨基酸替换或基序之间未发现关联。我们的数据表明，PMCV是从挪威引入法罗群岛的，已知挪威的亲鱼受到感染。然而，尽管挪威鱼卵的进口量稳步增加，但我们的结果表明，没有持续将持续存在的PMCV毒株重新引入法罗群岛养殖的鲑鱼中。
