Origins and relationships of Shigella and enteroinvasive Escherichia coli

志贺氏菌和肠侵袭性大肠杆菌的起源和关系

• 批准号: nhmrc : 211144
• 负责人: A/Pr Ruiting Lan
• 金额: $ 25.16万
• 依托单位国家: 澳大利亚
• 项目类别: NHMRC Project Grants
• 财政年份: 2002
• 资助国家: 澳大利亚
• 起止时间: 2002-01-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://researchdata.edu.au/origins-relationships-shigella-escherichia-coli/95636
• 关键词: Origins; relationships; Shigella; enteroinvasive; Escherichia

Shigella is a well known highly infectious human pathogen with as few as 10 cells allowing effective spread by infected food or water, and also by person to person contact. Shigellosis is a particularly significant disease for children due to lack of pre-existing immunity and greater chance of transfer by fecal-oral route. One group of E. coli called Enteroinvasive E. coli (EIEC) resembles Shigella in many aspects from disease symptoms to biochemical properties. EIEC is a major cause of diarrhoea in less developed countries and has also caused large outbreaks in developed countries. It is now clear that Shigella and E. coli are really one species. EIEC and Shigella strains are variants of E. coli with humans as the only host. However separation of the two in all records and most studies means that there is no integrated understanding of the forms. We aim to study the relationships of Shigella and EIEC and expect significant insights into the origins of Shigella-EIEC. This will facilitate diagnosis and understanding of the disease(s) and lead to a far better classification . EIEC-Shigella strains have arisen from other E. coli independently. This has happened seven times in the derivation of Shigella and we expect more such events with EIEC. An interesting phenomenon during this process is that strains tend to lose metabolic functions. In this study we will look at what, why and how functions are lost. O antigens are important in evading the host immune system. Shigella strains obtained many O antigens, the majority apparently from other species. This is quite likely the key to its success. We will look at how Shigella obtained new O antigens. This project will be significant in the understanding of Shigell-EIEC, a very significant human pathogen, and in general for understanding emergence of new pathogens.

志贺氏菌是一种众所周知的高度传染性的人类病原体，只有10个细胞，可以通过受感染的食物或水有效传播，也可以通过人与人之间的接触传播。由于缺乏预先存在的免疫力和更大的机会通过粪-口途径传播，志贺氏菌病是儿童的一种特别重要的疾病。一组E.大肠杆菌称为肠侵袭性E.大肠杆菌（EIEC）与志贺氏菌在疾病症状和生化特性等方面具有相似性。EIEC是欠发达国家腹泻的主要原因，也在发达国家造成大规模暴发。目前已明确志贺氏菌和E.大肠杆菌其实是一个物种EIEC和志贺菌是大肠杆菌的变异株。大肠杆菌，人类是唯一的宿主。然而，在所有的记录和大多数研究中，两者的分离意味着没有对形式的综合理解。我们的目的是研究志贺菌和EIEC的关系，并期望对志贺菌-EIEC的起源有重要的见解。这将有助于疾病的诊断和理解，并导致更好的分类。EIEC-志贺菌菌株起源于其他的E.大肠杆菌中。在志贺氏菌的衍生中，这种情况发生了七次，我们预计EIEC会发生更多这样的事件。在这个过程中，一个有趣的现象是菌株往往会失去代谢功能。在这项研究中，我们将看看什么，为什么和如何失去功能。O抗原在逃避宿主免疫系统中是重要的。志贺氏菌菌株获得了许多O抗原，大多数显然来自其他物种。这很可能是它成功的关键。我们将研究志贺氏菌如何获得新的O抗原。该项目将对了解Shigell-EIEC这一非常重要的人类病原体以及了解新病原体的出现具有重要意义。