脑膜炎奈瑟菌健康人群中优势克隆群的筛选及其与流行关系的研究

Neisseria meningitidis is the pathogenic bacteria causing meningococcal diseases. N. meningitidis has evolved attributes that generally enable harmless colonisation of the human nasopharynx, its only known niche. Adhesion is the major factors accocited with N. meningitidis virulence and spreading. The health carrier strains are considered as one source of hyperinvasive lineages. The dominant clones of health carrier strains can enhance their virulence and transmissibility through genetic variation, then cause epidemic of meningococcal diseases. In this study, we should choose health carrier strains isolated in intermittent period of meningococcal diseases epidemic in China. We should analyze the population structure of health carrier strains. We should used PCR amplification, DNA hybridization and sequencing to describe the distribution and polymorphism of adhesion-related gene/gene cluster in health carrier strains. And then, use MLVA and SNP to analyze the evolutionary relationships of dominant clones of health carrier strains and hyperinvasive lineages strains, and compare the adhesive capacity of the A549 and HEp-2 cells of these two types of N. meningitidis strains. The strains having nearer phylogenetic relationship with hyperinvasive lineages strains and having stronger adhesion ability may become a potential hyperinvasive lineages strain.

脑膜炎奈瑟菌是引起流脑的病原细菌，人是其唯一宿主。粘附是脑膜炎奈瑟菌毒力和传播最主要的因素。健康人群携带的脑膜炎奈瑟菌被认为是高致病克隆群菌株的来源之一。健康人群菌株基因多态性大，但是也存在克隆性。某些优势克隆群可以通过各种变异方式获得粘附相关基因，从而增强毒力和传播能力，成为引起流脑流行的潜在菌群。本研究以我国流脑流行间歇期，选取健康人群分离的脑膜炎奈瑟菌，通过分子分型方法描述其菌群结构特征，采用PCR扩增、DNA杂交和测序技术分析粘附相关基因/基因簇在健康人群菌株中的分布和多态性；随后挑选优势克隆群菌株与流行菌株相比较，通过MLVA和SNP的方法研究健康人群优势克隆群菌株与流行菌株的进化关系，同时比较两类菌株对A549和HEp-2细胞的粘附能力。与流行菌株亲缘关系进、具有较强粘附能力的菌株克隆群将有可能成为潜在的流行株而引起流脑的流行。本研究旨在阐述健康人群携带菌株与流脑流行的关系。

脑膜炎奈瑟菌是引起流脑的病原细菌，人是其唯一宿主。粘附是脑膜炎奈瑟菌毒力和传播最主要的因素。健康人群携带的脑膜炎奈瑟菌被认为是高致病克隆群菌株的来源之一。健康人群菌株基因多态性大，但是也存在克隆性。某些优势克隆群可以通过各种变异方式获得粘附相关基因，从而增强毒力和传播能力，成为引起流脑流行的潜在菌群。本项目通过对健康人群携带的脑膜炎奈瑟菌进行粘附相关基因/基因簇的分布和序列多态性特征分析，结合MLST分型分析，揭示了我国健康人群中存在ST11型W135群（class II型pilE、nadA阳性）、ST4821型B群（class I型pilE、nadA阴性）、ST2146型不可分群（class I型pilE、nadA阴性）优势克隆群；以VNTR和SNP为遗传标记，构建进化树，揭示各健康人群优势克隆群与病人分离株克隆群直接的关系，其中健康人群ST11型W135群菌株与病人分离的ST11型W135群菌株为同一克隆；健康人群ST4821型B群菌株与我国目前流行的ST4821型C群菌株遗传关系近；ST2146型不可分群菌株与其它克隆群关系远；挑选各优势克隆群代表菌株进行对HEp-2 细胞的粘附能力检测，结果显示ST11型W135群和ST4821型B群具有高粘附能力，ST2146型不可分群菌株粘附能力低，提示ST11型W135群和ST4821型B群具有导致流脑流行的风险，而ST2146型不可分群菌株目前导致流脑流行的可能性小。