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：
7620544
负责人：
Arnold Lee Smith
金额：
$ 15.47万
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 2009-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7620544
关键词：
Affect Anatomic Sites Anatomy Animal Model Animals Antibodies Bacteremia Bacteria Blood Blood Circulation Bronchitis Child Clinical DNA DNA Restriction-Modification Enzymes DNA biosynthesis Disease Drug Delivery Systems Ear 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 Lung Membrane Proteins Meningitis Methylation Methyltransferase Microarray Analysis Modeling Nasopharynx Neisseria meningitidis Nontypable Haemophilus influenza Numbers Nutrient Ohio Organism Otitis Otitis Media Parents Pathogenesis Pattern Pharyngeal structure Phase Physiological Physiological Adaptation Prevention Production Proteins Rattus Regulation Reporting Role Site Structure Surface Switch Genes Systemic infection Tandem Repeat Sequences Tetranucleotide Repeat Universities Upper Respiratory Infections Vaccines Variant Virulent Work base genome sequencing member middle ear migration mutant novel prevent promoter rapid technique tool

项目摘要

DESCRIPTION (provided by applicant): 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. Haemophilus influenzae is a bacterium that usually grows harmlessly in the human throat, but is also able to cause disease. If we can understand how these bacteria change as they move from the throat to sites of infection (such as the ear, lungs, or blood), we may someday be able to prevent disease.

描述（由申请人提供）：流感嗜血杆菌是正常细菌菌群的成员。它也是上呼吸道感染的原因，例如中耳炎和支气管炎以及全身感染，例如菌血症和脑膜炎。理想情况下，预防或治疗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。这项工作的长期目标是了解从无症状定植到粘膜或全身感染的过渡。我们假设鼻咽细菌适应新环境（例如中耳或血液）的一种机制之一是DNA甲基酶基因的相变。在流感嗜血杆菌中已经研究了表面结构（例如外膜蛋白和脂多糖）的相位变化数年。 MOD基因包含一个串联重复区域，类似于在流感h. h. h. h. h. h. h. h. h. h. the的其他良好的相变基因中鉴定的区域，但是直到最近，MOD相变的生理作用尚不清楚。我们的合作者通过微阵列分析将MOD缺失突变体与MOD+父母进行了比较，并报道MOD影响至少15个基因的转录（Srikhanta etal。2005PNAS 102：5547-51）显然是通过启动子的甲基化。并非所有这些基因都具有已知的功能，但是通常由MOD表达上调的基因参与营养的获取，而在Heathock组中，由MOD表达下调的几个基因都在热冲突组中。有人提出，mod的相变是一种随机，协调/关闭几个基因的协调的机制。这些研究使用了实验室适应的无毒应变RD KW20。在流感烟草和其他粘膜生物（如奈瑟氏菌）的临床分离株中，也已经鉴定出了相变的mod基因。这个探索性项目将研究这种毒性h.脑杆菌中基因调节的新型机制，（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将来的研究提供有关细菌对人宿主内不同解剖壁ni的生理适应的基础。流感嗜血杆菌是一种通常在人类喉咙中无害生长的细菌，但也能够引起疾病。如果我们能够了解这些细菌在从喉咙转移到感染部位（例如耳朵，肺或血液）时如何变化，我们可能有一天能够预防疾病。