Whole genome analysis of Yersinia ruckeri isolated over 27 years in Australia and New Zealand reveals geographical endemism over multiple lineages and recent evolution under host selection.
Whole genome analysis of Yersinia ruckeri isolated over 27 years in Australia and New Zealand reveals geographical endemism over multiple lineages and recent evolution under host selection.
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DOI：
10.1099/mgen.0.000095
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发表时间：
2016-11
影响因子：
3.9
通讯作者：
Carson J
中科院分区：
文献类型：
--
作者：
Barnes AC;Delamare-Deboutteville J;Gudkovs N;Brosnahan C;Morrison R;Carson J
鲁氏耶尔森氏菌（Yersinia ruckeri）是一种广泛分布于冷温带沃茨的鲑鱼病原体，包括澳大利亚和新西兰，这两个孤立的环境最近发展了鲑鱼养殖业。基于非重组核心基因组SNP对来自澳大利亚、新西兰、美国、智利、芬兰和中国的58个分离株进行系统发育比较，发现多个深分支谱系，最近的共同祖先估计为18 500年前（12 355-24 757 95% HPD），并有澳大利亚特有的证据。塔斯马尼亚大西洋鲑鱼血清型O 1b谱系内的进化缓慢，27年来有63个SNP描述了变异。与1997年引入的疫苗接种前谱系相比，来自流行谱系的分离株运动性差/不运动，该谱系运动性高，但此后未从动物流行病中分离出。与欧洲和美国相比，塔斯马尼亚岛通过编码鞭毛簇ATP酶的fliI中的移码独立出现了非运动表型。我们报告的第一次脂多糖O-抗原血清型O2分离在塔斯马尼亚州。这种表型是由于O-抗原簇的缺失和随之而来的高分子量O-抗原的丢失造成的。这种现象在三个大陆（澳大拉西亚、北美和亚洲）独立发生了三次，因为来自美国、中国和塔斯马尼亚的O2分离株共享O抗原缺失，但占据遥远的谱系。尽管澳大拉西亚鲑科鱼类起源于欧洲和北美，但Y。澳大利亚和新西兰的ruckeri与北方的ruckeri不同，表明它们是预先存在的古老菌株，随着欧洲殖民化后引入易感宿主而出现和进化。
Yersinia ruckeri is a salmonid pathogen with widespread distribution in cool-temperate waters including Australia and New Zealand, two isolated environments with recently developed salmonid farming industries. Phylogenetic comparison of 58 isolates from Australia, New Zealand, USA, Chile, Finland and China based on non-recombinant core genome SNPs revealed multiple deep-branching lineages, with a most recent common ancestor estimated at 18 500 years BP (12 355–24 757 95% HPD) and evidence of Australasian endemism. Evolution within the Tasmanian Atlantic salmon serotype O1b lineage has been slow, with 63 SNPs describing the variance over 27 years. Isolates from the prevailing lineage are poorly/non-motile compared to a lineage pre-vaccination, introduced in 1997, which is highly motile but has not been isolated since from epizootics. A non-motile phenotype has arisen independently in Tasmania compared to Europe and USA through a frameshift in fliI, encoding the ATPase of the flagella cluster. We report for the first time lipopolysaccharide O-antigen serotype O2 isolates in Tasmania. This phenotype results from deletion of the O-antigen cluster and consequent loss of high-molecular-weight O-antigen. This phenomenon has occurred independently on three occasions on three continents (Australasia, North America and Asia) as O2 isolates from the USA, China and Tasmania share the O-antigen deletion but occupy distant lineages. Despite the European and North American origins of the Australasian salmonid stocks, the lineages of Y. ruckeri in Australia and New Zealand are distinct from those of the northern hemisphere, suggesting they are pre-existing ancient strains that have emerged and evolved with the introduction of susceptible hosts following European colonization.