H. influenzae Genes Associated with Acute Otitis Media

描述（由申请人提供）：急性中耳炎是宿主防御、环境因素和细菌毒力特性复杂相互作用的结果。先前的研究表明，不可分型流感嗜血杆菌（NTHi）是儿童急性中耳炎的重要病因，它具有独特的基因，在这种感染的发病机制中起重要作用。在这个项目中，我们将利用利用自然生物选择的流行病学方法确定与中耳炎相关的潜在NTHi因素。由于从中耳炎儿童中耳分离的NTHi似乎具有特定的基因，可以增加中耳细菌的适应性，而这对于NTHi在咽部的定植并不需要，因此我们将使用全细菌基因组DNA微阵列进行流行分析，以确定中耳炎菌株保留的NTHi基因与儿童咽部的NTHi共生菌株相比。该项目的具体目标是：1 .通过流行分析确定潜在的NTHi中耳炎相关基因，重点是已知的Hi毒力基因，通过中耳和咽喉菌株的硅片减法分析确定的基因，以及Hi遗传岛内的基因7。2。通过检测耳朵和喉咙菌株中主要基因等位基因的患病率，确定预测中耳炎的NTHi毒力基因的多态性。3。研究铁代谢基因在NTHi中耳炎中的作用，通过患病率分析和探索这些基因在铁依赖性NTHi生长和NTHi铁获取中的功能。IV.通过分类树分析确定由NTHi基因簇组成的中耳炎病理型，这些基因簇可以区分急性中耳炎菌株和咽喉菌株。V.在栗鼠模型中测试缺乏中耳炎相关基因的NTHi的毒力，作为基因发现策略识别中耳炎毒力基因的原理证明。鉴定独特的NTHi中耳炎相关因素和毒力途径将促进预防和治疗NTHi中耳炎的新方法的发展，这可能会保护NTHi在咽部的独特生态。该基因发现项目的结果将确定NTHi基因在中耳炎NTHi菌株中比在共生喉部菌株中更普遍，因此可能对中耳NTHi存活很重要，并与中耳炎疾病相关。由这些基因编码的蛋白质将成为多组分NTHi疫苗的有吸引力的候选物，因为针对中耳炎相关抗原将有望减少中耳炎，而不会大大干扰咽内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.