中国大肠杆菌O157:H7菌株特有质粒pO157_Sal功能研究

1999年我国苏皖地区发生了一起世界上规模最大的大肠杆菌O157:H7 暴发疫情，报告住院的溶血性尿毒综合症患者195例，报告死亡177人，估计发病20000余人。我们发现，导致苏皖疫情的大肠杆菌O157:H7菌株是一个独特的克隆，进化上与引起1996年日本万人感染的菌株相近，与引起美国1982年疫情的菌株较远，菌株毒力比日本暴发菌株和美国暴发菌株强。自1999年后，我国再也没有分离到相同的菌株。我们最近发现，苏皖疫情相关菌株携带一接合质粒pO157_Sal，与沙门菌的一个质粒同源性较高。这个质粒为中国O157:H7菌株所特有，国外菌株未检测到。本研究拟采取质粒消除、基因缺失、代谢谱分析、转录组和蛋白质组分析等技术，研究pO157_Sal的可能功能，特别是在环境适应性（耐酸、耐热、耐高渗、耐胆盐、碳源和氮源利用、生物膜形成、抗阿米巴吞噬）和致病性（细胞模型和致病动物模型）等方面的作用。

A massive outbreak of Escherichia coli O157:H7 occurred in Jiangsu and neighbor Anhui province, China, in 1999, with 195 hospitalized patients who had clinically diagnosed HUS,177 deaths and over 20,000 infections. The outbreak isolates were found to be a new clone, which are phylogenetically closely related to the Japan 1996 outbreak isolate Sakai, both of which share the most recent common ancestor with the US 1982 outbreak isolate EDL933.No such strains were isolated in China since 1999. In recently, a novel conjugative plasmid, pO157_Sal, which shares high similarity with a plasmid in Salmonella enterica serovar Agona, was detected in the outbreak isolates of Escherichia coli O157:H7. In this project, we will try to reveal the role of pO157_Sal in environmental fitness and pathogenicity.