H. influenzae Genes Associated with Acute Otitis Media

描述（由申请人提供）：急性中耳炎是由宿主防御、环境因素和细菌毒力特性的复杂相互作用引起的。以往的研究表明，不可分型流感嗜血杆菌（NTHi），急性中耳炎的儿童的一个重要原因，拥有独特的基因在这种感染的发病机制中的重要性。在这个项目中，我们将确定潜在的NTHi因素与中耳炎使用流行病学的方法，利用自然生物选择的优势。因为从患有中耳炎的儿童的中耳分离的NTHi似乎具有在中耳中提供增加的细菌适应性的特定基因，而这不是咽部的NTHi定殖所需的，所以我们将使用如在全细菌基因组DNA微阵列上进行的流行率分析来鉴定与儿童咽部中的NTHi咽部菌株相比由中耳炎菌株保留的NTHi基因。该项目的具体目标是：一。通过流行率分析识别潜在的NTHi中耳炎相关基因，重点关注已知的Hi毒力基因、通过中耳和咽喉菌株的计算机减影分析识别的基因以及Hi遗传岛7内的基因。二.通过检测耳和咽喉菌株中主要基因等位基因的流行率，确定NTHi毒力基因多态性，预测中耳炎。三.通过患病率分析和通过探索这些基因在铁依赖性NTHi生长和NTHi铁获得中的功能来研究铁代谢基因在NTHi中耳炎中的作用。四.通过分类树分析鉴定由区分急性中耳炎菌株和咽喉菌株的NTHi基因簇组成的中耳炎病理型。V.在灰鼠模型中测试缺乏中耳炎相关基因的NTHi的毒力，作为基因发现策略鉴定中耳炎毒力基因的原理证明。鉴定独特的NTHi中耳炎相关因子和毒力途径将促进开发新的方法来预防和治疗NTHi中耳炎，其可以保留NTHi在咽中的独特生态。公共卫生相关性该基因发现项目的结果将鉴定在中耳炎NTHi菌株中比在咽喉部菌株中更普遍的NTHi基因，并且因此可能对NTHi在中耳中的存活很重要并且与中耳炎疾病相关。由这些基因编码的蛋白质将是多组分NTHi疫苗的有吸引力的候选物，因为靶向中耳炎相关抗原将预期减少中耳炎，而不会极大地干扰咽中NTHi的生态。

DESCRIPTION (provided by applicant): Acute otitis media results from a complex interplay of host defenses, environmental factors, and virulence characteristics of bacteria. Previous studies suggest that non-typeable Haemophilus influenza (NTHi), an important cause of acute otitis media in children, possess unique genes important in the pathogenesis of this infection. In this project, we will identify potential NTHi factors associated with otitis media using an epidemiologic approach that takes advantage of natural biologic selection. Because NTHi isolated from the middle ears of children with otitis media appear to possess specific genes offering increased bacterial fitness in the middle ear that are not required for NTHi colonization of the pharynx, we will use prevalence analysis, as performed on a whole bacterial genomic DNA microarray, to identify NTHi genes retained by otitis media strains compared to NTHi commensal strains in the pharynges of children. The Specific Aims of this project are to: I. Identify potential NTHi otitis media-associated genes by prevalence analysis, focusing on known Hi virulence genes, genes identified through in silico subtraction analysis of middle ear and throat strains, and genes within Hi genetic island 7. II. Identify polymorphisms in NTHi virulence genes that predict otitis media by testing the prevalences of the major gene alleles among ear and throat strains. III. Investigate the role of iron metabolism genes in NTHi otitis media by prevalence analysis and by exploration of the function of these genes in iron dependent NTHi growth and in NTHi iron acquisition. IV. Identify by classification tree analysis otitis media pathotypes consisting of clusters of NTHi genes that discriminate acute otitis media strains from throat strains. V. Test for virulence of NTHi lacking otitis media-associated genes in a chinchilla model as proof-of- principle that the gene discovery strategy identifies otitis media virulence genes. Identification of unique NTHi otitis media-associated factors and virulence pathways will facilitate the development of novel approaches to the prevention and treatment of NTHi otitis media that may preserve the unique ecology of NTHi in the pharynges. PUBLIC HEALTH RELEVANCE The results of this gene discovery project will identify NTHi genes that are more prevalent among otitis media NTHi strains than among commensal throat strains, and thus likely to be important in NTHi survival in the middle ear and to be associated with the disease otitis media. Proteins encoded by these genes will be attractive candidates for a multi-component NTHi vaccine, as targeting otitis media-associated antigens would be expected to reduce otitis media without greatly disturbing the ecology of NTHi in the pharynx.