GENETICS VIRULENCE IN PSEUDOMONAS AERUGINOSA

铜绿假单胞菌产生多种胞外产物， 可能在假单胞菌感染的发病机制中起重要作用 在实验动物模型和人类身上。此外，我们和其他人 已经表明假单胞菌的毒力取决于它的能力 从环境中获取铁(Fe)或无机磷(PI)，以及 一些毒力决定因素的产生受这些因素的调控 离子。在铜绿假单胞菌胞外产物中，有两种毒素 在假单胞菌文献中已经被突出提到过 作为主要毒力决定因素的热门候选者。它们是外毒素A 其作用机制类似于白喉毒素和不耐热性 溶血素(磷脂酶C)，其作用机制类似于α 产气荚膜梭菌毒素。然而，这些措施的实际重要性 毒素在致病机理上连类假单胞菌感染都不是 但却完全理解。此外，这一点的具体机制 条件致病菌能够从环境中获得铁和磷 而这些机制在假单胞菌毒力中的重要性 还没有得到澄清。这项研究的总体目标是阐明 铜绿假单胞菌毒力的遗传和生化基础。这些 研究可能最终导致免疫疗法的合理发展 和/或对这种机会主义者引起的感染进行免疫预防 病原体。目前的目标如下：1)我们将隔离 定义明确的突变体，其产生毒力的能力发生了变化 因子(毒素)或其获得铁或磷的能力发生变化 从环境中释放出来。为了实现这一目标，我们将在体外使用 重组DNA技术否则我们将在体内使用经典微生物 基因技术(例如，R‘因子的产生)以克隆基因 毒力决定因素。2)我们将在克隆的基因中产生突变 基因通过体外或体内方法，然后将突变基因转移到 野生型假单胞菌。3)我们将在下面描述突变体的特征 通过遗传和生化方法进行详细描述。4)我们将比较 这些定义明确、特征明确的突变体对同基因的毒力 亲本菌株在适当的实验动物模型中。

Pseudomonas aeruginosa produces a variety of extracellular products which may play a significant role in the pathogenesis of Pseudomonas infections in experimental animal models and in humans. In addition we and others have shown that the virulence of Pseudomonas is dependent upon its ability to acquire iron (Fe) or inorganic phosphate (Pi) from the environment and jthat production of some virulence determinants is regulated by these ions. Of the extracellular products of P. aeruginosa, two toxins along with protease have been mentioned prominently in the Pseudomonas literature as likey candidates for major virulence determinants. They are Exotoxin A which has a mechanism of action like diphtheria toxin and the Heat-labile Hemolysin (Phospholipase C) which has a mechanism of action like the alpha toxin of Clostridium perfringens. However, the actual importance of these toxins in the pathogenesis of even on kind of Pseudomonas infection is not yet fully understood. In addition, the specific mechanism by which this opportunistic pathogen is able to acquire Fe and Pi from the environment and the importance of these mechanisms in the virulence of Pseudomonas have not been elucidated. The overall goal of this research is to elucidate the genetic and biochemical bases for the virulence of P. aeruginosa. These studies may ultimately lead to the rational development of immunotherapy and/or immunoprophylaxis for infections caused by this opportunistic pathogen. The immediate objectives are as follows: 1) we will isolate well-defined mutants whih are altered in their ability to produce virulence factors (toxins) or which are altered in their ability to acquire Fe or Pi from the environment. To accomplish this objective, we will use in vitro recombinant DNA techniques or we will use in vivo classical microbial genetic techniques (e.g., generation of R' factors) to clone genes for virulence determinants. 2) We will generate mutations in those cloned genes by in vitro or in vivo methods and then transfer the mutant genes to wild-type Pseudomonas strains. 3) We will characterize the mutants in detail by genetic and biochemical methods. 4) We will compare the virulence of these well-defined, well-characterized mutants to the isogenic parental strains in appropriate experimental animal models.