鲍曼不动杆菌宿主内进化的遗传变异规律和调控机制研究

Acinetobacter baumannii is the common causes of hospital acquired infection and colonization. The occurrence of A. baumannii infection is closely related to the colonization in the host. The within-host evolution of bacteria is accompanied by resistance and fitness variation. However, the genetic variation and regulatory mechanism of within-host evolution has not yet elucidated in A. baumannii. Our previous study found that the population structure change and genetic variation of transcriptional regulators occurred in the patient with A. baumannii from colonization to infection. To confirm the genetic variation and regulatory mechanism of within-host evolution in A. baumannii, the A. baumannii clinical isolates isolated from the same patient at different times and different specimen types will be selected. The study will analyze the population structure change and evolution characteristics of A. baumannii from colonization to infection by whole genome sequencing and comparative genomic analysis. Meanwhile, the evolution mechanisms of tigecycline and/or polymyxin resistance will be analyzed, and novel resistant genes and mutations will be discovered. The regulatory mechanism of transcriptional regulators on the virulence and fitness evolution of A. baumannii will be clarified using RNA sequencing and transcriptomic analysis. This study will clarify the genetic variation characteristics of within-host evolution in A. baumannii, and identify the regulatory mechanism of important genes evolved in within-host evolution. This promising project will provide the evidence for control and treatment strategy of A. baumannii, and put forward innovative theory for development of novel antibiotics.

鲍曼不动杆菌是院内感染常见的定植菌和致病菌，其感染的发生与宿主内定植密切相关。菌株在宿主内进化过程中伴随耐药性和适应性的变化，但鲍曼不动杆菌宿主内进化的遗传变异规律和调控机制尚未阐明。前期研究发现，鲍曼不动杆菌从定植发展为感染的过程中存在菌群结构的改变和转录调控基因的多态性变化。为明确鲍曼不动杆菌宿主内进化的遗传变异规律和调控机制，本项目拟对同一患者不同时间不同部位分离的鲍曼不动杆菌，采用全基因组测序和比较基因组分析，明确定植到感染过程中菌群结构特征和进化规律；分析替加环素和/或多粘菌素宿主内耐药性进化的作用机制，寻找新的耐药基因和突变位点；采用RNA测序和转录组学分析，阐明转录调控基因对细菌毒力和适应性进化的调控机制。本研究将阐明鲍曼不动杆菌宿主内进化的遗传变异规律，明确宿主内进化的关键分子及调控机制，研究结果可为鲍曼不动杆菌的防控、用药策略和新药的研发提供重要科学依据。

鲍曼不动杆菌是院内感染常见的致病菌，其感染的发生与定植密切相关。菌株在宿主内进化过程中伴随耐药性和适应性的变化，但鲍曼不动杆菌宿主内进化的遗传变异规律和调控机制尚未阐明。本项目对同一患者不同时间不同部位分离的鲍曼不动杆菌，采用全基因组测序和比较基因组分析，明确定植到感染过程中菌群结构特征和进化规律。鲍曼不动杆菌菌血症的宿主内进化是由突变、基因构成变化和有限的重组驱动的；不同患者之间的基因含量的差异表明宿主和病原体因素在宿主内遗传多样性中的相互作用；分泌系统相关基因在宿主内进化过程中表现出较高的基因组变异频率。鲍曼不动杆菌在替加环素治疗后出现了一种特殊的表型，伴随着血清耐受性降低、生物膜形成能力增强和大蜡螟毒力降低；大多数基因组变异发生在替加环素治疗后，主要涉及转录、信号转导、翻译、核糖体生物发生和细胞壁生物发生相关基因；baeR、wzc、aroQ、rluC和adeS的基因组变异以及ISAba1的获得与鲍曼不动杆菌体内替加环素耐药进化相关，荚膜多糖相关基因wzc、itrA2和aroQ是鲍曼不动杆菌宿主内毒力进化相关的关键基因。发现质粒介导的新替加环素耐药相关基因tet(Y)，携带tet(Y)基因的分离株易受替加环素压力的影响，容易形成替加环素耐药；携带tet(Y)的质粒在宿主菌株中保持稳定；转座元件Tn5393可能在其传播中起作用。发现琼氏不动杆菌黏菌素耐药相关基因PmrB、LpxA、LpxD及其重要突变位点。构建宿主内进化关键调控基因gspJ基因敲除株，采用RNA测序和转录组学分析，阐明gspJ对细菌毒力和适应性进化的调控机制。综上所述，本项目阐明了鲍曼不动杆菌宿主内进化的遗传变异规律，明确宿主内进化的关键分子及调控机制，研究结果可为鲍曼不动杆菌的防控和治疗新药的研发提供重要的科学依据。