Canuti Marta, O'Leary Kimberly E, Hunter Bruce D, Spearman Grant, Ojkic Davor, Whitney Hugh G, Lang Andrew S
Department of Biology, Memorial University of Newfoundland, 232 Elizabeth Ave., St. John's, Newfoundland and Labrador, A1B 3X9, Canada.
Animal Health Division, Forestry and Agrifoods Agency, P.O. Box 7400, St. John's, Newfoundland and Labrador, A1E 3Y5, Canada.
Virus Evol. 2016 Feb 27;2(1):vew004. doi: 10.1093/ve/vew004. eCollection 2016 Jan.
Aleutian mink disease virus (AMDV) causes plasmacytosis, an immune complex-associated syndrome that affects wild and farmed mink. The virus can also infect other small mammals (e.g., ferrets, skunks, ermines, and raccoons), but the disease in these hosts has been studied less. In 2007, a mink plasmacytosis outbreak began on the Island of Newfoundland, and the virus has been endemic in farms since then. In this study, we evaluated the molecular epidemiology of AMDV in farmed and wild animals of Newfoundland since before the beginning of the outbreak and investigated the epidemic in a global context by studying AMDV worldwide, thereby examining its diffusion and phylogeography. Furthermore, AMDV evolution was examined in the context of intensive farming, where host population dynamics strongly influence viral evolution. Partial NS1 sequences and several complete genomes were obtained from Newfoundland viruses and analyzed along with numerous sequences from other locations worldwide that were either obtained as part of this study or from public databases. We observed very high viral diversity within Newfoundland and within single farms, where high rates of co-infection, recombinant viruses and polymorphisms were observed within single infected individuals. Worldwide, we documented a partial geographic distribution of strains, where viruses from different countries co-exist within clades but form country-specific subclades. Finally, we observed the occurrence of recombination and the predominance of negative selection pressure on AMDV proteins. A surprisingly low number of immunoepitopic sites were under diversifying pressure, possibly because AMDV gains no benefit by escaping the immune response as viral entry into target cells is mediated through interactions with antibodies, which therefore contribute to cell infection. In conclusion, the high prevalence of AMDV in farms facilitates the establishment of co-infections that can favor the occurrence of recombination and enhance viral diversity. Viruses are then exchanged between different farms and countries and can be introduced into the wild, with the rapidly evolving viruses producing many parallel lineages.
阿留申水貂病病毒（AMDV）可引发浆细胞增多症，这是一种与免疫复合物相关的综合征，会影响野生和养殖水貂。该病毒也能感染其他小型哺乳动物（如雪貂、臭鼬、白鼬和浣熊），但对这些宿主所患疾病的研究较少。2007年，纽芬兰岛爆发了水貂浆细胞增多症疫情，自那时起该病毒在养殖场中呈地方流行状态。在本研究中，我们评估了自疫情爆发前以来纽芬兰养殖和野生动物中AMDV的分子流行病学，并通过研究全球范围内的AMDV来调查其在全球范围内的流行情况，从而探究其传播和系统地理学。此外，在集约化养殖的背景下研究了AMDV的进化，在这种情况下宿主种群动态对病毒进化有强烈影响。从纽芬兰病毒中获得了部分NS1序列和几个完整基因组，并与全球其他地点的众多序列一起进行分析，这些序列要么是本研究的一部分，要么来自公共数据库。我们在纽芬兰以及单个养殖场内观察到了非常高的病毒多样性，在单个感染个体中观察到了高共感染率、重组病毒和多态性。在全球范围内，我们记录了毒株的部分地理分布情况，不同国家的病毒在进化枝中共存，但形成了特定国家的亚进化枝。最后，我们观察到了重组的发生以及AMDV蛋白上负选择压力的主导地位。处于多样化压力下的免疫表位位点数量惊人地少，这可能是因为病毒进入靶细胞是通过与抗体相互作用介导的，因此AMDV通过逃避免疫反应无法获得益处，而抗体反而有助于细胞感染。总之，AMDV在养殖场中的高流行率促进了共感染的发生，这可能有利于重组的发生并增加病毒多样性。然后病毒在不同养殖场和国家之间传播，并可能引入野生环境，快速进化的病毒产生了许多平行谱系。
