A specific genetic background is required for acquisition and expression of virulence factors in Escherichia coli
A specific genetic background is required for acquisition and expression of virulence factors in Escherichia coli
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DOI：
10.1093/molbev/msh118
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发表时间：
2004-06-01
影响因子：
10.7
通讯作者：
Denamur, E
中科院分区：
文献类型：
--
作者：
Escobar-Páramo, P;Clermont, O;Denamur, E
在细菌。致病性的进化似乎是毒力因子（VFs）不断进入细菌基因组的结果。然而，这些因子的整合、保留和/或表达可能是新到达的基因与细菌基因组背景相互作用的结果。为了验证这一假设，对98株大肠杆菌/志贺氏菌进行了系统发育分析，这些菌株代表了该物种的致病性和共生多样性。不同大肠杆菌病原菌相关的17个VFs分布叠加在系统发育树上。可以识别出三种主要类型的VFs:(1) VFs在不同的遗传背景下到达并表达（例如与轻度慢性腹泻的病原体相关的VFs：肠聚集性，肠致病性和弥漫性粘附性大肠杆菌），(2)VFs在不同的遗传背景下到达，但优先发现，与特定病理相关，仅在一个特定背景下（例如与肠外疾病相关的VFs）。(3)需要特定遗传背景才能到达和表达其毒力潜力的VFs（例如与严重急性腹泻的典型病原体相关的VFs：肠出血性、肠产毒素和肠侵入性大肠杆菌菌株）。通过将其中一些VFs的进化历史与菌株的系统发育进行比较，排除了偶然到达VFs的可能性，然后是垂直传播。这些证据表明，大肠杆菌在物种多样化过程中发生了重要的基因组变化，从而使与严重急性腹泻相关的毒力因子进入种群。因此，大肠杆菌基因组似乎是由“祖先”和“衍生”背景形成的，每一个都负责获取和表达不同的毒力因子。
In bacteria. the evolution of pathogenicity seems to be the result of the constant arrival of virulence factors (VFs) into the bacterial genome. However, the integration, retention, and/or expression of these factors may be the result of the interaction between the new arriving genes and the bacterial genomic background. To test this hypothesis, a phylogenetic analysis was done on a collection of 98 Escherichia coli/Shigella strains representing the pathogenic and commensal diversity of the species. The distribution of 17 VFs associated to the different E. coli pathovars was superimposed on the phylogenetic tree. Three major types of VFs can be recognized: (1) VFs that arrive and are expressed in different genetic backgrounds (such as VFs associated with the pathovars of mild chronic diarrhea: enteroaggregative, enteropathogenic, and diffusely-adhering E. coli), (2) VFs that arrive in different genetic backgrounds but are preferentially found, associated with a specific pathology, in only one particular background (such as VFs associated with extraintestinal diseases). and (3) VFs that require a particular genetic background for the arrival and expression of their virulence potential (such as VFs associated with pathovars typical of severe acute diarrhea: enterohemorragic, enterotoxigenic, and enteroinvasive E. coli strains). The possibility of a single arrival of VFs by chance, followed by a vertical transmission, was ruled out by comparing the evolutionary histories of some of these VFs to the strain phylogeny. These evidences suggest that important changes in the genome of E. coli have occurred during the diversification of the species, allowing the virulence factors associated with severe acute diarrhea to arrive in the population. Thus, the E. coli genome seems to be formed by an "ancestral" and a "derived" background, each one responsible for the acquisition and expression of different virulence factors.