HAEMOPHILUS INFLUENZAE B VIRULENCE: ROLE OF HAEMOCIN

描述(改编自申请者摘要)：流感嗜血杆菌是一种 人类特有的致病菌引起多种严重的 儿童感染，包括肺炎、蜂窝织炎、感染性关节炎、 会厌炎。此外，流感嗜血杆菌是引起 美国细菌性脑膜炎，影响约12,000人 每年都有孩子。尽管最近在抗菌治疗方面取得了进展，但 由流感嗜血杆菌感染引起的发病率和死亡率发生了变化 在过去的十年里几乎没有。有两个因素清楚地区分了 从相对无毒的地方引起侵袭性感染的流感嗜血杆菌 本种的成员：存在由多糖组成的胶囊 多聚核糖基核糖醇磷酸(PRP)及其细菌素的生产 一种称为血球蛋白的蛋白质。鉴于PRP胶囊已经广泛应用于 作为一个毒力因子，血球蛋白的作用还没有被研究过 调查过了。 该提案旨在调查血球菌素在猪细小病毒致病中的作用。 流感嗜血杆菌。为了明确地定义这一角色， 血球蛋白产量将被确定，编码血球蛋白的基因(S) 将被克隆。将对克隆的血球蛋白基因进行诱变 构建只有不同基因的流感嗜血杆菌同源菌株 生产血球菌素的能力。这些同源菌株将被用来 用一种方法确定血球菌素生产对毒力的影响 流感嗜血杆菌感染相关动物模型的建立。相对能力 HMC和HMC-菌株的定植和入侵幼鼠将是 评估过了。这个项目的另一个目标是提纯和表征 血球蛋白。血球蛋白在以下方面的潜在作用 通过介导对哺乳动物宿主细胞的直接毒性作用而产生的毒力 通过调查血球菌素生产对 相关人体组织的体外实验。血球蛋白是否应该被证明是重要的 毒力、克隆的血凝素基因及其蛋白的可用性 产品将允许进一步调查，旨在定义新的 预防流感嗜血杆菌感染的策略。

DESCRIPTION (Adapted from applicant's abstract): H. influenzae is a human-specific bacterial pathogen responsible for a variety of serious infections in children, including pneumonia, cellulitis, septic arthritis, and epiglottitis. Further, H. influenzae is the most common cause of bacterial meningitis in the United States, affecting approximately 12,000 children annually. Despite recent advances in antimicrobial therapy, the morbidity and mortality resulting from H. influenzae infection has changed little during the past decade. Two factors clearly distinguish strains of H. influenzae which cause invasive infection from relatively avirulent members of this species: the presence of polysaccharide capsule composed of polyribosyl ribitol phosphate (PRP) and the production of a bacteriocin protein termed haemocin. Whereas the PRP capsule has been extensively examined as a virulence factor, the role of haemocin has not been investigated. This proposal seeks to investigate the role of haemocin in the virulence of H. influenzae. To unambiguously define this role, the genetic basis of haemocin production will be determined, and the gene(s) encoding haemocin will be cloned. Mutagenesis of the cloned haemocin gene will be performed to construct isogeneic strains of H. influenzae differing only in their ability to produce haemocin. These isogeneic strains will then be used to determine the effect of haemocin production in virulence by using a relevant animal model of H. influenzae infection. The relative abilities of HMC+ and HMC-strains to colonize and to invade infant rats will be assessed. Another goal of this project is to purify and characterize the haemocin protein. The potential role of haemocin in contributing to virulence by mediating a direct toxic effect upon mammalian host cells will be examined by investigating the effects of haemocin production upon relevant human tissue in vitro. Should haemocin prove important in virulence, the availability of the cloned haemocin gene and its protein product will permit further investigations designed to define new strategies for the prevention of H. influenzae infection.