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征的复杂相互作用的结果。以往的研究表明，非型性流感嗜血杆菌(NTHi)是儿童急性中耳炎的重要原因，具有独特的基因，在这种感染的发病机制中发挥重要作用。在这个项目中，我们将使用一种利用自然生物选择的流行病学方法来确定与中耳炎相关的潜在NTHi因素。由于从患有中耳炎的儿童中耳分离的NTHi似乎具有提高中耳细菌适合性的特定基因，而这些基因对于NTHi在咽部的定植并不是必需的，因此我们将使用对整个细菌基因组DNA微阵列进行的患病率分析，以确定中耳炎菌株与NTHi共生菌株在儿童咽喉中保留的NTHi基因。本项目的具体目标是：1.通过流行分析寻找潜在的NTHi中耳炎相关基因，重点是已知的Hi毒力基因，通过中耳和喉部菌株的电子消减分析确定的基因，以及Hi基因岛上的基因。7.通过检测主要基因等位基因在耳和喉部菌株中的流行情况，识别预测中耳炎的NTHi毒力基因的多态。通过患病率分析，探讨铁代谢基因在铁依赖的NTHi生长发育和NTHi铁获取中的作用，探讨铁代谢基因在NTHi中耳炎中的作用。通过分类树分析鉴定由NTHi基因簇组成的中耳炎致病类型，以区分急性中耳炎菌株和咽喉菌株。V.在龙猫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则证明。识别独特的NTHi中耳炎相关因素和毒力途径将有助于开发新的方法来预防和治疗NTHi中耳炎，从而保护NTHi在咽部的独特生态。公共卫生相关性这一基因发现项目的结果将确定NTHi基因在中耳炎NTHi株中比在共生性咽喉株中更常见，因此可能对NTHi在中耳存活并与中耳炎有关的重要作用。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者，因为靶向中耳炎相关抗原有望在不严重干扰咽部NTHi生态的情况下减少中耳炎。

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.