Genetic requirements of Helicobacter pylori infection

描述(申请人提供)：幽门螺杆菌(Hp)慢性感染全球50%的人口的胃。10%到20%的感染者最终会出现严重的疾病，包括溃疡和胃癌。我们的工作假设是，幽门螺杆菌病是建立和维持感染所必需的细菌因素与由此产生的宿主防御之间相互作用的副产品。此外，这种相互作用是动态的，在数十年的感染过程中，细菌修改宿主，宿主修改细菌。为了研究这一复杂的过程，我们利用了一种小鼠感染模型，该模型概括了人类疾病的许多方面，包括无法清除感染和胃腺结构改变的强大免疫反应。利用这个模型，我们将在体内表征已知的HP毒力因子的功能，并对新的Hp毒力基因进行饱和筛选。直到最近，由于缺乏实验工具，这样的屏幕才成为可能。在目标1中，我们研究了主要分泌的细胞毒素VacA在体内的作用，我们首次证明了VacA在小鼠感染过程中具有表型。在目标2中，我们描述了一种用于识别其他HP毒力基因的筛查方法。在这里，我们利用了我们最近开发的两个工具：HP转座子突变体文库和一种名为Matt的新方法，该方法使用我们的Hp cDNA微阵列来监测池中的转座子突变。我们相信这一筛查有可能为我们提供建立和维持感染所需的幽门螺杆菌基因的全球视角。最后，在目标3中，我们研究了PAI，这是一组毒力基因，最近被证明介导了许多与培养细胞的特定相互作用。我们描述了为什么到目前为止还没有该基因座的体内表型被描述的实验，以及测量PAI在小鼠感染过程中的作用的新实验。对VacA中突变株的感染进行仔细研究，PAI基因和新发现的毒力因子有可能通过揭示突变株感染中未能发生的过程来告诉我们许多关于野生型感染的信息。这些过程可能导致与幽门螺杆菌相关的各种疾病，并可能突出潜在的治疗目标。

DESCRIPTION (provided by applicant): Helicobacter pylori (Hp) chronically infect the human stomach of 50% of the population worldwide. Ten to 20% of those infected will eventually present with severe disease including ulcers and gastric cancers. Our working hypothesis is that Hp disease is a by-product of the interaction between bacterial factors necessary for establishing and maintaining infection and the resultant host defenses. Furthermore, this interaction is dynamic with the bacteria modifying the host and the host modifying the bacteria over decades of infection. To study this complex process, we utilize a mouse model of infection which recapitulates many aspects of human disease including a robust immune response that is unable to clear the infection and alteration of gastric gland architecture. Using this model we will characterize the function of known Hp virulence factors in vivo and perform a saturating screen for new Hp virulence genes. Such a screen has not been possible until recently due to lack of experimental tools. In Aim 1 we examine the in vivo role of the major secreted cytotoxin, VacA, which we were the first to demonstrate has a phenotype during mouse infection. In Aim 2 we describe a screen to identify additional Hp virulence genes. Here we take advantage of two tools we recently developed: an Hp transposon mutant library and a novel methodology we call MATT to monitor transposon mutants in a pool using our Hp cDNA microarray. We believe this screen has the potential to gives us a global view of the Hp genetic requirements for establishing and maintaining infection. Finally, in Aim 3 we investigate the PAI, a group of virulence genes that have been recently shown to mediate a number of specific interactions with cultured cells. We describe experiments that address why no in vivo phenotype for this locus has been described to date and new experiments to measure a role for the PAI during mouse infection. Careful study of infection with mutants in vacA, the PAI genes and newly identified virulence factors have the potential to teach us a great deal about wild type infection by revealing process that fail to occur in mutant infections. These processes likely contribute to the various diseases associated with Hp and may highlight potential therapeutic targets.