群体感应I型系统在禽致病性大肠杆菌致病进程中的功能研究

细菌群体感应系统在自然界广泛存在，可释放、感知特定信号分子，确定周边环境中同类或不同类细菌数量，并据此调节多种毒力基因，正发展成为微生物学科内的一个相对热点领域。然而I型群体感应系统对大肠杆菌毒力的调控、尤其是禽致病性大肠杆菌（APEC）致病机制的调控尚未明确。基于I型群体感应系统对猪源大肠杆菌相关毒力的调控前提研究和积累，申请者着手从APEC致病途径中分离能够通过I型群体感应系统影响大肠杆菌毒力的I型群体感应信号分子AHL阳性菌株；检测信号分子AHL影响下APEC毒力变化及毒力因子间协同调控关系；通过iTRAQ技术筛选APEC在I型群体感应系统影响下与毒力变化相关表达差异蛋白，应用生物信息学分析其生物功能，筛选群体感应调控下毒力变化相关重要通路。本课题对揭示大肠杆菌群体感应系统功能，阐明I型群体感应系统在APEC致病性中调控作用具有重要的理论意义，为研究APEC致病机理提供实验基础。

Quorum Sensing (QS) is widespread in nature. During growth, bacteria can utilize QS signals to sense cell population density in surrounding environment, subsquently regulate the genes expression. This regulation mechanism is called Quorum Sensing, developing into a relatively hot research area of microorganism. However, QS regulation mechanism upon E.coli, especially avian pathogenic Escherichia coli (APEC), have not been elucidated clearly. Based on the accumulated related data and main biomaterials involved in QS-I regulation function on swine sourced E.coli, applicants will focus on regulation mechanism of QS-I upon APEC virulence, and develop improved methods to identify AHLs positive bacteria interacting with APEC through QS-I system. Meanwhile AHL positive recombinant APEC strain will be constructed to explore QS-I function upon APEC virulence, and explore co-regulation relationship of APEC virulence factors. Protein of both recombinant strain and wild type would be extracted to screen the differential expressed proteins through iTRAQ technique. Bioinformatics technique would be employed to analyze biological functions of the target proteins for virulence related potential pathways. This study would deeply elucidate QS function of E. coli, and supply important data for QS-I regulation on pathogenic mechanism of APEC.