Quorum Sensing in H. influenzae otitis

描述（由申请人提供）： 渗出性中耳炎（OME）是儿童的一个重要健康问题。流感嗜血杆菌是这种疾病的主要原因之一。流感嗜血杆菌 OME 的特点包括频繁复发和抗生素无法根除。解释流感嗜血杆菌 OME 这些特征的一个假设是，该生物体在中耳中以生物膜的形式生长。细菌生物膜的特点是对抗生素治疗不敏感，并且无法被宿主炎症反应消除。患有 OME 的儿童体内存在流感嗜血杆菌生物膜的证据包括这些儿童的中耳液中存在短暂的嗜血杆菌特异性 mRNA。革兰氏阴性细菌生物膜的形成取决于群体感应转录激活剂（称为自诱导剂）的合成。我们发现流感嗜血杆菌；包括从中耳分离的那些具有能够合成自诱导剂（AI-2）的基因（HI0491）。流感嗜血杆菌实验室菌株 Rd KW20 中的 HI0491 插入失活会产生突变体，该突变体缺乏形成成熟生物膜结构的能力，并且在 OME 动物模型中降低了对抗生素的敏感性、接合频率和存活率。 在此应用中，我们试图表征几种原型“耳炎”流感嗜血杆菌在体外的生物膜形成，评估这些菌株在断奶大鼠和龙猫中引起的实验性 OME，确定自诱导剂在这种疾病中的作用，并定义 AI-2 在体外和体内生物膜发育中的作用。了解 AI-2 和生物膜形成在 OME 中的作用将有助于制定预防或治疗这种疾病的策略。

DESCRIPTION (provided by applicant): Otitis media with effusion (OME) is a significant health problem of children. Haemophilus influenzae is one of the major causes of this disease. Features of H. influenzae OME include frequent recurrences and a failure of eradication with antibiotic administration. One hypothesis explaining these features of H. influenzae OME is that the organism is growing as a biofilm in the middle ear. Bacterial biofilms are characteristically insensitive to antibiotic treatment, as well as incapable of elimination by the host inflammatory response. Evidence of a H. influenzae biofilm in children with OME consists of the presence of short-lived, Haemophilus-specific mRNA in the middle ear fluid of these children. Gram-negative bacterial biofilm formation is dependent upon the synthesis of quorum-sensing transcriptional activators, called autoinducers. We have found that H. influenzae; including those isolated from the middle ear possess a gene (HI0491) capable of synthesizing an autoinducer (AI-2). Insertional inactivation of HI0491 in the H. influenzae laboratory strain Rd KW20 results in a mutant, which lacks the ability to form mature biofilm structures, and has decreased susceptibility to antibiotics, a decreased conjugation frequency and decreased survival in an animal model of OME. In this application, we are seeking to characterize biofilm formation by several prototypic "otitic" H. influenzae in vitro, assess experimental OME caused by these strains in the weanling rat and chinchillas, determine the role of the autoinducer in this disease and define the role of AI-2 in biofilm development in vitro and in vivo. Understanding the role of AI-2 and biofilm formation in OME will permit strategies to prevent or treat this disease to be devised.