Gene Discovery for Pneumococcal Otitis Media

描述(申请人提供)：中耳炎(OM)是美国寻求医疗护理的幼儿中最常见的细菌感染，肺炎链球菌菌株是细菌性OM的主要原因。这些革兰氏阳性双球菌在多达50%的健康儿童的呼吸道中定居，只有在特殊情况下才会致病。最近的基因组测序项目和分子生物学的进展导致了许多假定的毒力因子的鉴定。这些因素主要在肺炎等侵袭性肺炎球菌疾病的背景下进行研究，或在一种或几种实验室菌株中进行研究。虽然仍有更多的毒力因子有待发现，但新的挑战是确定这些因素中哪些值得进一步研究，将这些因素与OM的发病机制联系起来，并估计这些毒力因子在循环中肺炎链球菌菌株中的相对重要性。这个项目是建立在观察到肺炎链球菌菌株在致病能力上的不同，以及这些差异可能是由于延伸到多糖胶囊之外的菌株之间的遗传差异的基础上的。该项目的目标是确定肺炎链球菌OM的相关基因，并评估从健康儿童和患有临床疾病的儿童获得的分离株中肺炎球菌毒力基因的相对频率。一种利用分子生物学和流行病学技术的四步跨学科方法将包括：1.选择具有最高潜力识别与OM相关的基因的肺炎链球菌进行基因组消减。2.利用基因组消减技术鉴定引起OM的菌株(测试菌株)所特有的、健康携带者的菌株(驱动菌株)所不存在的DNA序列(SPCR片段)。3.使用SPCR片段对来自健康儿童和患有OM、脑膜炎、肺炎或菌血症的儿童的大量分离株进行流行病学筛选。4.确定与OM发病有关的SPCR片段的相关基因，并描述其生物学和临床特征。发现更多与链球菌性OM有关的因素将有助于制定控制和预防这一重要疾病的新战略。

DESCRIPTION (provided by applicant): Otitis media (OM) is the most common bacterial infection in the United States among young children for which medical care is sought, and Streptococcus pneumoniae strains are the leading cause of bacterial OM. These gram-positive diplococci colonize the respiratory tract in up to 50% of healthy children and only cause disease under special circumstances. Recent genomic sequencing projects and advancements in molecular biology have resulted in the identification of numerous putative virulence factors. These factors have mainly been studied in the context of invasive pneumococcal diseases such as pneumonia, or have been studied in one or a few laboratory strains. While more virulence factors remain to be discovered, the new challenge is to identify which of these many factors warrant further study, to link these factors specifically to OM pathogenesis, and to estimate the relative importance of these virulence factors among the S. pneumoniae strains in circulation. This project is built on the observation that S. pneumoniae strains differ in their ability to cause disease, and that these differences are likely due to genetic differences between strains that extend beyond the polysaccharide capsule. The goal of this project is to identify genes associated with pneumococcal OM and to evaluate the relative frequency of pneumococcal virulence genes among a collection of isolates obtained from healthy children and children with clinical disease. A four step interdisciplinary approach utilizing techniques of molecular biology and epidemiology will include: 1. Selection of S. pneumoniae strains for genomic subtraction with the highest potential to identify genes associated with OM. 2. Identification of DNA sequences (sPCR fragments) unique to strains causing OM (tester strains) and absent in strains from healthy carriers (driver strains) using genomic subtraction. 3. Epidemiologic screening of a large collection of isolates from healthy children and children with OM, meningitis, pneumonia, or bacteremia using sPCR fragments. 4. Identification of genes associated with sPCR fragments important for OM pathogenesis and description of their biological and clinical characteristics. Discovery of additional factors involved in streptococcal OM will facilitate the development of new strategies for the control and prevention of this important disease.