Identifying novel Pseudomonas Aeruginosa pathogenesis-associated genomic islands

描述（由申请方提供）：哺乳动物病原体铜绿假单胞菌的感染过程部分取决于所有细菌菌株表达的充分表征的毒力因子的表达，但微生物致病能力存在显著的菌株间差异。基因组岛，即细菌基因组中所含的DNA区域，在菌株之间存在差异，占铜绿假单胞菌基因组的10%，但仍然相对未开发。在这些基因组岛内存在或不存在非保守的毒力因子可能在调节菌株之间的致病性中起作用。先前的研究已经从铜绿假单胞菌临床分离株中鉴定出几个基因组岛，这些基因组岛增加了呼吸道感染的严重程度。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，将从铜绿假单胞菌血流感染的医院患者中获得细菌分离株，并在菌血症小鼠模型中进行检测，以鉴定最毒力菌株。将对特别高毒力铜绿假单胞菌菌株的基因组进行测序，并与参考铜绿假单胞菌菌株进行比较，以鉴定临床分离株中的新基因组岛。在目标2中，将进行来自高毒力铜绿假单胞菌分离株的基因组岛的缺失和互补，以鉴定与毒力最相关的那些基因组岛。然后，将对与毒力相关的基因组岛进行逐段缺失，其效果将在菌血症小鼠模型中进行检查。这些研究将确定与增强的致病性相关的毒力因子编码基因组岛内的特定ORF。本研究的完成将确定新的铜绿假单胞菌致病性相关的基因组岛和毒力因子，深入了解铜绿假单胞菌感染过程中差异的机制。 公共卫生相关性：该提案的成功完成将通过确定影响主要人类病原体铜绿假单胞菌感染性的新型毒力决定因素，极大地促进医学科学的进步。这些研究的结果也将为未来研究铜绿假单胞菌临床感染的过程以及开发针对铜绿假单胞菌的新型治疗方法提供新的靶点。

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.