IRON AQUISITION BY HAEMOPHILUS AEGYPTIUS

描述：本研究提案的长期目标是 铁获取系统的分子和遗传解剖， 流感嗜血杆菌埃及亚种（Haemophilus influenzae aegyptius）。埃及伊蚊）菌株 巴西紫癜热（BPF） BPF是一种爆发性的 儿童败血症是由H.埃及人， 称为BPF克隆。 虽然取得了实质性进展， 自1985年描述第一例BPF以来， 导致BPF克隆毒力增强的因子 仍然未知。 基因产物和调控机制， 细菌在宿主中生存所必需的 细菌毒力库的组成部分。 这是一个重要 生物学方面的研究。埃及BPF克隆，因为它必须入侵 结膜和/或鼻咽粘膜，存活并在 血液产生BPF的典型组织病理学病变。 期间 在这个过程中，细菌必须获得必需的营养物质，如铁， 一种金属，虽然在宿主中丰富，但不能自由获得， 微生物生长 致病细菌利用 这种在其它情况下不可利用的铁在细菌毒力中是重要的。 目前，对H.埃及的 是未知的，来自几个实验室的初步数据， H.流感病毒表明，这种细菌的铁吸收系统是 复杂. 因此，铁的收购和监管的审查， 是控制发病的重要区域， 对这种暴发性疾病的预防相关研究。 而且 在这项研究中获得的知识将增加我们对 H. 不同于经典B型分离株的流感病毒株。 到 为了实现这些目标，研究计划包括：（1）遗传和 转铁蛋白结合蛋白（TBP 1和 TBP2）。 TBP 1和/或TBP 2同基因突变体的产生将允许 评估这些蛋白质在铁获得中的作用;（2） 识别和分析与 铁从表面受体转移到胞质溶胶。 的 Fbp和TonB样蛋白的存在将通过分子生物学方法进行评估。 克隆和DNA测序、诱变和互补测定; (3)铁的表达的调节的表征- 抑制蛋白质 与E. 通过克隆和诱变的方法对大肠杆菌Fur蛋白进行研究 分析. 此外，一种新的遗传方法（毛皮滴定法） 将被用于确定新的毛皮调节基因在H。 埃及人。

DESCRIPTION: The long-term objective of this research proposal is the molecular and genetic dissection of the iron acquisition systems in Haemophilus influenzae biogroup aegyptius (H. aegyptius) strains isolated from cases of Brazilian purpuric fever (BPF). BPF is a fulminant septicemic disease in children caused by a single clone of H. aegyptius, referred to as the BPF clone. Although substantial progress has been made since the description of the first case of BPF in 1985, the factor(s) responsible for the enhanced virulence of the BPF clone remains unknown. Gene products and regulatory mechanisms that are essential for bacterial survival in the host are considered substantial components of the bacterial virulence repertoire. This is an important aspect in the biology of the H. aegyptius BPF clone as it must invade the conjunctiva and/or nasopharyngeal mucosa, survive and multiply in the blood to produce the typical histopathologic lesions of BPF. During this process, the bacteria must acquire essential nutrients such as iron, a metal that, although abundant in the host, is not freely available for microbial growth. Mechanisms whereby a pathogenic bacterium can utilize this otherwise unavailable iron are important in bacterial virulence. Currently, the molecular mechanisms of iron utilization by H. aegyptius are unknown and preliminary data from several laboratories working on H. influenzae suggest that the iron-uptake systems in this bacterium are complex. Thus, the examination of iron acquisition and the regulation of its expression are significant areas for pathogenesis-control and prevention-related studies on this fulminant disease. Furthermore, the knowledge gained during this study will increase our understanding of the pathogenesis of other bacterial invasive diseases caused by H. influenza strains different from the classical type b isolates. To achieve these goals, the research plan includes: (1) genetic and molecular characterization of the transferrin-binding proteins (TBP1 and TBP2). Generation of TBP1 and/or TBP2 isogenic mutants will permit assessment of the role of these proteins in iron acquisition; (2) identification and analysis of the components associated with the transfer of iron from the surface receptor to the cytosol. The existence of Fbp- and TonB-like proteins will be evaluated by molecular cloning and DNA sequencing, mutagenesis, and complementation assays; (3) characterization of the regulation of the expression of iron- repressed proteins. The presence of a repressor homologous to the E. coli Fur protein will be investigated by cloning and mutagenesis analysis. In addition, a novel genetic approach (Fur titration assay) will be used to identify new Fur-regulated genes in H. aegyptius.