普罗威登斯菌O抗原多样性进化机制及其与细菌致病性关系的系统研究

O-antigen is a major surface antigen of Gram-negative bacteria. It is essential for the survival and virulence of bacteria, and exhibits one of the richest diversities in nature. The gene cluster responsible for the synthesis of O-antigen is one of the most variable regions in bacterial chromosome, and is one of the most suitable materials for studying the laws of evolutionary routes that are relevant in pathogenic bacteria. Enterobacteria of the genus Providencia are opportunistic human pathogens associated with urinary tract infections, as well as enteric diseases. The isolation rate of Providencia strains and their threat to humans have been reported to be increased in recent years. However, there is no systematic study on the O-antigen diversity in Providencia species and relevant genetic generation mechanism. In this project, 49 Providencia O-antigen gene clusters will be sequenced. Together with the data that we have obtained before, the sequences of all 61 Providencia O-antigen gene clusters will be available. The O-antigen structrues of 6-8 highly pathogenic and virulent strains will be determined. The molecular mechanisms for the formation of Providencia O-antigen diversity will be systematically analyzed. We will also biochemically identify the biosynthesis pathways for several novel monosaccharides and oligosaccharides found in Providencia O-antigens. The relationship between the O-serotypes and the pathogenicity of Providencia strains will be studied, and a lot of genes related with the virulence of Providencia strains will be revealed and identified. On the basis of these data, we will have a better understanding for the molecular basis of the pathogenicity difference among various Providencia strains belonging to different O-serotypes. We will also develop a molecular O-serotyping system for Providencia strains, which will be very useful for the rapid detection of clinical pathogenic bacteria strains and epidemiological survey.

O抗原是革兰氏阴性菌的主要表面抗原，具有生物界中最丰富的多样性之一，且与致病性密切相关。负责其合成的基因簇是细菌染色体上最具多变性的区域，是研究分子进化的最适材料之一。普罗威登斯菌是常见条件致病菌，可引起肠道、尿路感染，近年来其分离率和对人类威胁逐渐增大，但目前尚无对该菌O抗原多样性的系统研究。本项目将破译49种普罗威登斯菌的O抗原基因簇，结合前期数据，从而获得其全部61种O抗原的遗传信息。解析6-8种存在于强致病性菌株中的O抗原化学结构。全面分析普罗威登斯菌O抗原多样性的遗传进化机制。生化鉴定普罗威登斯菌O抗原中新发现的多种罕见单糖和糖链的合成途径。将系统研究O血清型与普罗威登斯菌致病性的关系，发现和鉴定与普罗威登斯菌致病能力相关的一系列基因，深入认识不同O血清型菌株致病性差异的分子机理。首次建立针对普罗威登斯菌O血清型的分子分型体系，为该菌的检测、流行病学调查、溯源等提供技术保障。