鲍曼不动杆菌碳青霉烯耐药基因进化和水平播散调控机制

碳青霉烯耐药鲍曼不动杆菌（CRAB）在全球广泛流行，解答碳青霉烯耐药基因在鲍曼不动杆菌中如何迅速播散是进一步控制其流行的重中之重。耐药基因水平转移是鲍曼不动杆菌获得碳青霉烯耐药性、进化为CRAB的重要机制，但该类基因如何实现其在不动杆菌菌株间转移？决定基因转移效率的关键元件及调控机制是什么？宿主获得耐药基因后，通过何种方式调控自身适应新的耐药状态？等关键科学问题仍然不清楚。在前期已有CRAB耐药机制及基因组研究数据的良好基础上，本课题拟运用全基因组测序及比较基因组学分析技术、Tn5突变体库及TraDIS测序，基因敲除和回补、蛋白重组及表达等多种方法和技术，对碳青霉烯耐药基因不同水平转移模式及效率、耐药调控元件、宿主菌适应性变化及染色体补偿突变位点等进行深入研究，探索耐药基因在不动杆菌间的水平转移规律及调控机制，阐明宿主耐药进化过程，最终揭示CRAB流行播散规律，为CRAB防控提供科学依据。

Carbapenem-resistant Acinetobacter baumannii (CRAB) has disseminated throughout the world, which arise widely attention. Research on illustrating the possible dissemination mechanism of carbapenem resistant genes among Acinetobacter isolates is one of the most important issues to control CRAB dissemination. Lateral gene transfer (LGT) of carbapenem resistant genes is a vital and common way in which A. baumannii obtains carbapenem resistance and further evolutes to CRAB. However, nowadays some key questions on LGT have yet been answered. We neither know how the resistant gene transfer happens between different Acinetobacter strains, nor what the essential factors or modules are managing the whole transferring process? And we don’t know how the host adjusts itself to fit the fresh resistant status? On the basis of our previous researches of resistant mechanisms of CRAB, this project aims to explore the LGT mechanisms and efficiencies of carbapenem resistant genes among Acinetobacter isolates by using different LGT models. By using Tn5 insertion mutant library and TraDIS sequencing, we can discover the key modules monitoring and regulating the whole process of LGT. To explore the process of the resistant evolution of CRAB, we plan to reveal the fitness cost of the host cell after obtaining the carbapenem resistant genes and identify the following up mutations on chromosome using multiple experimental methods like WGS and comparative genomics, gene knock-out and complementation experiment, protein recombination and expression methods. and provide more evidences on explaining the spreading mechanism of carbapenem resistance and the evolutionary process of CRAB. Our project will finally reveal the evolution process of carbapenem resistant gene in CRAB and further provide scientific evidences in the aspects of nosocomial infection control.