Role of phase-variable DNA methylase in virulence of Haemophilus influenzae

相变DNA甲基化酶在流感嗜血杆菌毒力中的作用

基本信息

批准号：
7498028
负责人：
Arnold Lee Smith
金额：
$ 28.11万
依托单位：
SEATTLE CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-09-30 至 2010-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7498028
关键词：
Affect Anatomic Sites Anatomy Animal Model Animals Antibodies Bacteremia Bacteria Blood Circulation Bronchitis Child Clinical DNA DNA Restriction-Modification Enzymes DNA biosynthesis Disease Drug Delivery Systems Environment Enzymes Future Gene Expression Regulation Genes Genetic Transcription Genome Goals Haemophilus influenza virulence Haemophilus influenzae Heat-Shock Response Human Individual Infant Infection Influenza Initiator Codon Knock-out Laboratories Lipopolysaccharides Membrane Proteins Meningitis Methylation Methyltransferase Microarray Analysis Modeling Nasopharynx Neisseria meningitidis Nontypable Haemophilus influenza Numbers Nutrient Ohio Organism Otitis Otitis Media Parents Pathogenesis Pattern Phase Physiological Physiological Adaptation Prevention Production Proteins Rattus Regulation Reporting Role Structure Surface Switch Genes Systemic infection Tandem Repeat Sequences Tetranucleotide Repeat Universities Upper Respiratory Infections Vaccines Variant Virulent Work abstracting base genome sequencing member middle ear migration mutant novel promoter rapid technique tool

项目摘要

Abstract Haemophilus influenzae is a member of the normal bacterial flora colonizing the human nasopharynx. It is also a cause of infections of the upper respiratory tract, such as otitis media and bronchitis, and of systemic infections, such as bacteremia and meningitis. Ideally, prevention or treatment of H. influenzae disease would affect only disease-associated bacteria without perturbing normal flora. The long-term goal of this work is to understand the transition from asymptomatic colonization to mucosal or systemic infection. We hypothesize that one of the mechanisms by which nasopharyngeal bacteria adapt to a new environment such as the middle ear or the bloodstream is phase variation of a DNA methylase gene, mod. Phase variation of surface structures such as outer membrane proteins and lipopolysaccharide has been studied in H. influenzae for several years. The mod gene contains a tandem repeat region similar to those identified in other, well-characterized phase-variable genes in H. influenzae, but a physiologic role for mod phase variation was unknown until recently. Our collaborators compared a mod deletion mutant with a mod+ parent by microarray analysis and reported that mod affects transcription of at least 15 genes (Srikhanta et al. 2005 PNAS 102:5547-51) apparently via methylation of promoters. Not all of these genes have known functions, but generally genes upregulated by mod expression are involved in nutrient acquisition, while several of those downregulated by mod expression are in the heat-shock group. It is proposed that phase variation of mod is a mechanism for random, coordinated on/off switching of several other genes. These studies used the laboratory-adapted, avirulent strain Rd KW20. Phase-variable mod genes have also been identified in clinical isolates of H. influenzae and in other mucosal organisms such as Neisseria meningitidis. This exploratory project will study this novel mechanism of gene regulation in virulent H. influenzae, (i) using microarrays to identify mod-related genes in clinical isolates and (ii) examining the effect of mod phase in experimental infections. Finding that mod regulation is common in clinical isolates and affects pathogenesis will provide the basis for future studies on the physiological adaptation of bacteria to different anatomic niches within the human host.

抽象的流感嗜血杆菌是正常细菌菌群的成员鼻咽。它也是上呼吸道感染的原因，例如中耳炎和支气管炎和全身感染，例如菌血症和脑膜炎。理想情况下，预防或治疗 h.流感障碍疾病将仅影响与疾病相关的细菌，而不会扰动正常菌群。这这项工作的长期目标是了解从无症状殖民到粘膜或全身感染。我们假设鼻咽细菌的一种机制之一到新环境（例如中耳或血液）是DNA甲基酶的相变基因，mod。表面结构的相变，例如外膜蛋白和脂多糖已经在流感h。 mod基因包含一个串联重复区域相似的区域对于在h. h. h. h. th. 对于mod阶段变化，直到最近才知道。我们的合作者比较了mod删除突变体通过微阵列分析，通过mod+ penth （Srikhanta等人2005 PNAS 102：5547-51）显然是通过启动子的甲基化。并非所有这些基因具有已知功能，但通常由MoD表达上调的基因参与营养采集，而几个被mod表达下调的人在热冲突组中。这是提出，mod的相变是一种随机的机制其他基因。这些研究使用了实验室适应的无毒应变RD KW20。相变模在流感烟草的临床分离株和其他粘膜生物（例如奈瑟氏菌脑膜炎。这个探索性项目将研究这种毒性中基因调节的新机制 H.流感，（i）使用微阵列在临床分离株和（ii）检查mod阶段在实验感染中的影响。发现MOD调节在临床分离株中很常见，并且影响发病机理将为未来关于细菌对人类宿主内不同解剖壁ni的生理适应的研究。