Genetic requirements of Helicobacter pylori infection

描述（由申请人提供）：幽门螺杆菌（Hp）慢性感染全球50%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，Hp疾病是建立和维持感染所必需的细菌因子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，细菌修饰宿主，宿主在几十年的感染中修饰细菌。为了研究这个复杂的过程，我们利用小鼠感染模型，该模型再现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应答。使用这个模型，我们将在体内已知的幽门螺杆菌毒力因子的功能的特点，并进行新的幽门螺杆菌毒力基因的饱和筛选。由于缺乏实验工具，这种屏幕直到最近才成为可能。在目的1中，我们研究了主要分泌的细胞毒素VacA在体内的作用，我们是第一个证明在小鼠感染过程中具有表型的。在目标2中，我们描述了一个筛选，以确定额外的Hp毒力基因。在这里，我们利用我们最近开发的两个工具：一个Hp转座子突变库和一种新的方法，我们称之为MATT监测转座子突变体在一个池中使用我们的Hp cDNA微阵列。我们相信这种筛选有可能使我们对建立和维持感染的Hp遗传要求有一个全面的了解。最后，在目标3中，我们研究了派，一组毒力基因，最近已被证明介导了一些特定的相互作用与培养的细胞。我们描述的实验，解决为什么没有在体内表型的这个位点已被描述到目前为止，新的实验来衡量的派在小鼠感染过程中的作用。仔细研究vacA突变体的感染，派基因和新发现的毒力因子有可能通过揭示突变体感染中未发生的过程来教会我们很多关于野生型感染的知识。这些过程可能导致与Hp相关的各种疾病，并可能突出潜在的治疗靶点。

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.