Clade analysis of enterohemorrhagic Escherichia coli serotype O157:H7/H- strains and hierarchy of their phylogenetic relationships
Clade analysis of enterohemorrhagic Escherichia coli serotype O157:H7/H- strains and hierarchy of their phylogenetic relationships
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DOI：
10.1016/j.meegid.2012.07.003
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发表时间：
2012-12-01
影响因子：
3.2
通讯作者：
Uchimura, Masako
中科院分区：
文献类型：
--
作者：
Yokoyama, Eiji;Hirai, Shinichiro;Uchimura, Masako
通过谱系、亚群、聚类和进化枝分析，对 2002-2009 年在日本千叶县分离的肠出血性大肠杆菌血清型 O157:H7/H-(O157) 菌株进行了研究。利用谱系特异性多态性分析6对470株尚无已知流行病学关系的O157株进行谱系分析，其中谱系I株242株，谱系I/II株160株，谱系II株67株，非典型株1株。通过8个位点的单核苷酸多态性对这些菌株进行进化枝分析表明，谱系I包含所有进化枝1、进化枝2和进化枝3菌株以及一些进化枝4/5菌株。相反，进化枝 7、进化枝 8 和其余的进化枝 4/5 菌株分为谱系 I/II 和 II，而进化枝 6 属于谱系 I/II，表明这些谱系的并系进化。 stx噬菌体插入位点的聚类和亚群分析表明，所有谱系I菌株都属于聚类3，所有谱系和II菌株（除了进化枝9之外）都属于聚类1。进化枝分析还表明，进化枝4/5菌株存在三个系统发育组：包含谱系I/II和II菌株的祖先组和包含谱系I的后代组。stx2c基因分布分析表明，stx2c处于聚类中。祖先分支 4/5 菌株，但在后代 4/5 菌株中没有，表明祖先群体可能是曼宁等人报道的分支 4。本研究使用的标记结果表明，O157系统发育关系的层次结构是谱系为上层，其次是亚群，然后是聚类，支系为最低层。讨论了完善分支定义和修改 O157 进化模型的必要性。 (C) 2012 Elsevier B.V. 保留所有权利。
Enterohemorrhagic Escherichia coli serotype O157:H7/H-(O157) strains isolated in Chiba prefecture, Japan, during 2002-2009 were studied by lineage, subgroup, cluster, and clade analysis. Lineage analysis of 470 O157 strains with no known epidemiological relationships using lineage specific polymorphism assay-6 showed that there were 242 lineage I strains, 160 lineage I/II strains, 67 lineage II strains, and 1 atypical strain. Clade analysis of these strains by single nucleotide polymorphism in eight loci showed that lineage I contained all the clade 1, clade 2, and clade 3 strains, and some of the clade 4/5 strains. In contrast, clade 7, clade 8, and the remaining clade 4/5 strains were divided between lineage I/II and II, and clade 6 was in lineage I/II, suggesting paraphyletic evolution of these lineages. Cluster and subgroup analysis of the stx phage insertion site showed that all lineage I strains were cluster 3 and all lineage and II strains, with the exception of clade 9, were in cluster 1. Clade analysis also indicated that there were three phylogenetic groups of clade 4/5 strains: ancestral groups containing lineage I/IIand II strains and a descendant group containing lineages I. Analysis of stx2c gene distribution showed that stx2c was in ancestral clade 4/5 strains but not in descendant 4/5 strains, suggesting that the ancestral group may be clade 4 as reported by Manning et al. The results with the markers used in this study suggested that the hierarchy of O157 phylogenetic relationships was lineage as the upper level, followed by subgroup and then cluster, and clade as the lowest level. The need for refinement of clade definition and modification of the model of the O157 evolution have been discussed. (C) 2012 Elsevier B.V. All rights reserved.