Evolutionary genetics of a new pathogenic Escherichia species:: Escherichia albertii and related Shigella boydii strains
Evolutionary genetics of a new pathogenic Escherichia species:: Escherichia albertii and related Shigella boydii strains
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DOI：
10.1128/jb.187.2.619-628.2005
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发表时间：
2005-01-01
影响因子：
3.2
通讯作者：
Whittam, TS
中科院分区：
文献类型：
--
作者：
Hyma, KE;Lacher, DW;Whittam, TS
一种最初被描述为肺泡哈夫尼亚杆菌的细菌会导致兔腹泻，并引起类似于肠道致病性大肠杆菌的附着和消失的上皮损伤。随后的研究发现，类似于肺泡杆菌的菌株对内膜基因(EAE)探针呈阳性反应，并根据DNA的亲缘关系被归类为一个独特的埃希里希菌种，即阿尔伯蒂埃希菌。我们测定了五个阿尔伯蒂埃希氏菌菌株的多个看家基因的序列，并将这些序列与代表致病大肠杆菌和志贺氏菌主要群体的菌株的序列进行了比较。对14个基因的2,484个密码子位置的比较表明，阿尔伯蒂埃希菌株平均与致病性大肠杆菌株的7.4%的核苷酸位置相似，与鼠伤寒沙门氏菌的15.7%的核苷酸位置不同。有趣的是，阿尔伯蒂肠杆菌菌株被发现与博氏志贺氏菌血清型13(志贺氏菌B13)菌株密切相关，后者是大肠杆菌的远亲，代表了大肠杆菌属的一个不同的谱系。对内膜蛋白同源蛋白(EAE)的分析表明，阿尔伯蒂埃希氏菌和志贺氏菌B13的中心保守域相似，而不同于致病性大肠杆菌中发现的EAE变异体。对细胞致死性膨胀毒素基因簇(CDT)的序列分析还揭示了与E.Alberti、志贺氏菌B13和血清学上与7型链球菌相关的不可分型分离株的三个等位基因群。根据同义替换率，E.albertii-Shigella B13谱系估计是从2800万年前类似大肠杆菌的祖先中分裂出来的，并形成了一个明显的肠道病原体进化分支，该分支已辐射到具有不同毒力特性的群组。
A bacterium originally described as Hafnia alvei induces diarrhea in rabbits and causes epithelial damage similar to the attachment and effacement associated with enteropathogenic Escherichia coli. Subsequent studies identified similar H. alvei-like strains that are positive for an intimin gene (eae) probe and, based on DNA relatedness, are classified as a distinct Escherichia species, Escherichia albertii. We determined sequences for multiple housekeeping genes in five E. albertii strains and compared these sequences to those of strains representing the major groups of pathogenic E. coli and Shigella. A comparison of 2,484 codon positions in 14 genes revealed that E. albertii strains differ, on average, at similar to7.4% of the nucleotide sites from pathogenic E. coli strains and at 15.7% from Salmonella enterica serotype Typhimurium. Interestingly, E. albertii strains were found to be closely related to strains of Shigella boydii serotype 13 (Shigella B13), a distant relative of E. coli representing a divergent lineage in the genus Escherichia. Analysis of homologues of intimin (eae) revealed that the central conserved domains are similar in E. albertii and Shigella B13 and distinct from those of eae variants found in pathogenic E. coli. Sequence analysis of the cytolethal distending toxin gene cluster (cdt) also disclosed three allelic groups corresponding to E. alberti, Shigella B13, and a nontypeable isolate serollogically related to S. boydii serotype 7. Based on the synonymous substitution rate, the E. albertii-Shigella B13 lineage is estimated to have split from an E. coli-like ancestor similar to28 million years ago and formed a distinct evolutionary branch of enteric pathogens that has radiated into groups with distinct virulence properties.