Identifying novel Pseudomonas Aeruginosa pathogenesis-associated genomic islands

描述(由申请人提供)：感染哺乳动物病原体铜绿假单胞菌的过程在一定程度上取决于所有细菌菌株表达的具有良好特征的毒力因子的表达，但在生物致病能力方面存在显著的菌株之间的差异。基因组岛是细菌基因组中包含的DNA区域，在不同菌株之间存在差异，占铜绿假单胞菌基因组的10%，但仍相对未被探索。这些基因组岛中非保守毒力因子的存在或不存在可能在调节不同菌株之间的致病性方面发挥作用。先前的研究已经从铜绿假单胞菌临床分离株中确定了几个基因组岛，它们增加了呼吸道感染的严重性。本研究将进一步探讨铜绿假单胞菌基因组岛与致病性的关系。这将通过完成以下两个具体目标来实现：在目标1中，将从医院铜绿假单胞菌血液感染患者中获得细菌分离株，并在小鼠菌血症模型中进行测试，以确定毒力最强的菌株。一种超强毒力的铜绿假单胞菌菌株的基因组将被测序，并与参考的铜绿假单胞菌菌株进行比较，以确定临床分离株中的新基因组岛。在目标2中，将对超强毒力铜绿假单胞菌分离株的基因组岛进行缺失和互补，以确定与毒力最相关的基因组岛。然后，与毒力相关的基因组岛将被零星删除，其影响将在菌血症的小鼠模型中进行检验。这些研究将确定基因组岛中编码与增强致病性相关的毒力因子的特定ORF。这项研究的完成将确定与铜绿假单胞菌致病相关的新的基因组岛和毒力因子，从而深入了解铜绿假单胞菌感染过程中潜在的差异机制。 公共卫生相关性：这项提案的成功完成将通过识别影响人类主要病原体铜绿假单胞菌传染性的新的毒力决定因素，极大地促进医学的进步。这些研究结果还将为未来研究铜绿假单胞菌临床感染的过程以及开发治疗铜绿假单胞菌的新药物提供新的靶点。

DESCRIPTION (provided by applicant): The course of an infection with the mammalian pathogen Pseudomonas aeruginosa is, in part, dependent on the expression of well-characterized virulence factors expressed by all strains of the bacteria, but significant strain-to-strain differences exist in the ability of the organism to cause disease. Genomic islands, regions of DNA contained within the bacterial genome that vary between strains, comprise up to 10% of the P. aeruginosa genome, but remain relatively unexplored. The presence or absence of non- conserved virulence factors within these genomic islands may play a role in modulating pathogenicity from strain to strain. Prior studies have identified several genomic islands from P. aeruginosa clinical isolates that enhance the severity of respiratory infections. In this study, the relationship between genomic islands in P. aeruginosa and pathogenicity will be further explored. This will be accomplished by completing the following two specific aims: In Aim 1, bacterial isolates will be obtained from hospital patients with P. aeruginosa bloodstream infections and tested in a mouse model of bacteremia to identify the most virulent strains. The genome of a particularly hypervirulent P. aeruginosa strain will be sequenced and compared to a reference P. aeruginosa strain to identify novel genomic islands in the clinical isolate. In Aim 2, deletion and complementation of genomic islands from a hypervirulent P. aeruginosa isolate will be performed to identify those genomic islands most associated with virulence. The virulence-associated genomic islands will then be subjected to piecemeal deletions, the effects of which will be examined in a mouse model of bacteremia. These studies will identify the specific ORFs within the genomic islands encoding for virulence factors associated with enhanced pathogenicity. Completion of this study will identify novel P. aeruginosa pathogenicity-associated genomic islands and virulence factors, yielding insight into the mechanisms underlying differences in the courses of P. aeruginosa infections. PUBLIC HEALTH RELEVANCE: Successful completion of this proposal will contribute greatly to the advancement of medical science by identifying novel virulence determinants influencing the infectivity of the major human pathogen, P. aeruginosa. The findings from these studies will also offer new targets for future studies examining the course of P. aeruginosa clinical infection, as well as the development of novel therapeutics against P. aeruginosa.