Accessory Virulence Factors of Pseudomonas aeruginosa

 描述(由申请人提供)：尽管人们对区分不同细菌物种的致病属性已经投入了大量的注意力，但对物种内毒力差异的原因知之甚少。为什么特定细菌物种的某些菌株比其他菌株会导致更严重的感染，这一问题具有重要的临床意义，因为这将使医生能够识别和定位感染了特别具有侵略性的菌株的患者，并面临特别糟糕的结果的风险。在这一应用中，我们将重点放在细菌病原体铜绿假单胞菌(PA)上来解决这个问题。与大多数细菌一样，PA的基因组可以分为两部分：核心基因组，由所有PA细菌中存在的基因组成；辅助基因组，由在某些PA菌株中发现的基因组成，但在其他菌株中没有。虽然已经进行了大量的工作来表征由PA核心基因组编码的毒力决定因素，但附属基因组仍然相对未被探索。我们假设PA的附属基因组包含新的毒力基因，这些基因影响由这种细菌引起的感染的严重程度和类型。在前期工作中，我们使用了比较基因组学的方法来鉴定PA辅助基因组中的毒力基因。在这一应用中，我们建议对该方法发现的几种毒力因子的机制进行表征。我们在这里的目标是展示辅助基因组作为毒力因子储存库的潜力，以及有趣的作用机制。我们还将使用我们的PA数据库和我们的比较基因组学方法来识别允许PA导致特定疾病表现的辅助基因。为了实现这一点，我们将使用与两种不同类型的感染相关的PA分离株的亚群：上海热病和囊性纤维化。最后，我们将通过使用这种比较基因组学方法来识别辅助基因来解释为什么一些PA菌株比其他菌株更具细胞毒性，从而展示这种方法的多功能性。这些目标的完成将进一步确定副基因组在PA致病中的重要性，并识别新的毒力决定因素，赋予PA物种内菌株不同的感染表型。这项工作也将为未来的研究奠定基础，这些研究旨在确定这些基因是否构成了特别具有攻击性的PA菌株的基因组“指纹”。

 DESCRIPTION (provided by applicant): Although much attention has been devoted to understanding the pathogenic attributes that distinguish one bacterial species from another, less is known about the causes of intra-species differences in virulence. The question of why some strains of a particular bacterial species cause more severe infections than others has important clinical implications in that it would allow physicians to identify and target patients infected wih particularly aggressive strains and at risk for especially poor outcomes. In this application, we focus on the bacterial pathogen Pseudomonas aeruginosa (PA) to address this question. As with most bacteria, PA has a genome that can be divided into two parts: the core genome, which consists of those genes present in all PA bacteria, and the accessory genome, which consists of those genes found in some strains of PA but not others. Although a substantial amount of work has been performed on characterizing virulence determinants encoded by the PA core genome, the accessory genome remains relatively unexplored. We hypothesize that the accessory genome of PA contains novel virulence genes that impact the severity and type of infection caused by this bacterium. In preliminary work, we have used a comparative genomics approach to identify virulence genes in the PA accessory genome. In this application, we propose to characterize the mechanisms of several virulence factors uncovered by this approach. Our goal here is to demonstrate the accessory genome's potential as a reservoir for virulence factors with interesting mechanisms of action. We will also use our PA database and our comparative genomics approach to identify accessory genes that allow PA to cause specific disease manifestations. To accomplish this, we will use subsets of PA isolates associated with two distinct types of infection: Shanghai Fever and cystic fibrosis. Finally, we will show the versatility of this comparative genomics approach by using it to identify accessory genes that explain why some PA strains are more cytotoxic than others. Completion of these aims will further define the importance of the accessory genome in PA pathogenesis and identify novel virulence determinants that confer different infection phenotypes on strains within the PA species. This work will also lay the foundation for future studies aimed at determining whether these genes constitute genomic "fingerprints" for particularly aggressive PA strains.