Origins and relationships of Shigella and enteroinvasive Escherichia coli

志贺氏菌是一种众所周知的高度传染性人类病原体，只有10个细胞即可通过受感染的食物或水有效传播，也可通过人际接触传播。志贺氏菌病对儿童来说是一种特别重要的疾病，因为缺乏预先存在的免疫力，而且更有可能通过粪-口途径传播。肠侵入性大肠杆菌（EIEC）在许多方面与志贺氏菌相似，从疾病症状到生化特性。EIEC是欠发达国家腹泻的一个主要原因，也在发达国家造成大规模暴发。现在很清楚志贺氏菌和大肠杆菌实际上是一个物种。EIEC和志贺氏菌株是大肠杆菌的变种，人类是唯一的宿主。然而，在所有记录和大多数研究中，两者的分离意味着没有对形体的综合理解。我们的目标是研究志贺氏菌和EIEC的关系，并期望对志贺氏菌-EIEC的起源有重要的见解。这将有助于诊断和了解疾病，并导致更好的分类。eeic -志贺氏菌菌株是由其他大肠杆菌独立产生的。这种情况在志贺氏菌的衍生中已经发生了7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，为什么以及如何功能丧失。O抗原在逃避宿主免疫系统中很重要。志贺氏菌菌株获得许多O抗原，其中大多数显然来自其他物种。这很可能是它成功的关键。我们将看看志贺氏菌是如何获得新的O抗原的。这一项目将对理解一种非常重要的人类病原体——志贺菌- eiec具有重要意义，并对理解新病原体的出现具有重要意义。

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.