Mechanistic Studies Of The Staphylococcus aureus LukAB Cytotoxin

项目总结/摘要 金黄色葡萄球菌是造成大量医院和社区获得性感染的原因 国际吧治疗方案，以打击S。由于抗生素水平高， 缺乏有效的疫苗。因此，迫切需要制定有效的 针对这种生物体的治疗方法。关键的致病性生活方式的S。金黄色葡萄球菌是吞噬细胞的杀伤; 先天性免疫细胞是控制葡萄球菌感染的组成部分。因此，这一长期目标 研究计划是了解S.金黄色葡萄球菌伤害这些关键的免疫细胞。 我们已经描述了杀白细胞素A/B（LukAB）在保护S.金黄色 通过靶向和消除这些细胞吞噬细胞介导的杀伤。我们的工作已经确定LukAB是 存在于所有临床菌株中，但却是双组分成孔菌家族中最分歧的成员。 毒素;负责S。在离体感染期间，金黄色葡萄球菌介导的原代人吞噬细胞的死亡; 靶向CD 11b整联蛋白;通过优先靶向CD 11b的人I结构域表现出种属特异性 在鼠I-结构域上;在鼠和人感染期间在体内产生;并杀死人 白细胞由S.金黄色葡萄球菌从细胞外和细胞内环境。主 本申请的目的是：阐明LukAB与人CD 11b结合的机制， 定义种特异性决定因素，以开发改进的S.金黄色葡萄球菌感染（目的 1）;定义LukAB杀死人吞噬细胞的机制（目的2）;并描述 LukAB变异体与其他S. aureus克隆（Aim 3）。为了实现这些目标，我们建议 采用多学科的方法，结合分子生物学，遗传学，细胞免疫学， 基因组筛选和生物化学，以及离体和体内感染模型。了解 LukAB如何介导靶向和杀伤吞噬细胞的分子细节将提供对S. 金黄色葡萄球菌双组分成孔毒素杀死宿主细胞，以及这些毒素对金黄色葡萄球菌的重要性。金黄色 发病机制

PROJECT SUMMARY/ABSTRACT Staphylococcus aureus is responsible for a large number of hospital- and community-acquired infections worldwide. Therapeutic options to combat S. aureus infections are limited due to the high level of antibiotic resistance and lack of an effective vaccine. Thus, there is a significant need for the development of effective therapeutics against this organism. Critical to the pathogenic lifestyle of S. aureus is the killing of phagocytes; innate immune cells integral to the control of Staphylococcal infections. Thus, the long-term goal of this research program is to understand the mechanism employed by S. aureus to injure these critical immune cells. We have described that the leukocidin A/B (LukAB) plays an essential role in protecting S. aureus from phagocyte-mediated killing by targeting and eliminating these cells. Our work has established that LukAB is present in all clinical strains, yet is the most divergent member of the bi-component pore-forming family of toxins; is responsible for S. aureus-mediated demise of primary human phagocytes during ex vivo infections; targets the CD11b integrin; exhibits species specificity by preferentially targeting the human I-domain of CD11b over the murine I-domain; is produced in vivo during both murine and human infections; and kills human leukocytes when produced by S. aureus from both extracellular and intracellular environments. The primary goals of this application are to: elucidate the mechanism by which LukAB binds to human CD11b in order to define the species specificity determinants to develop an improved murine model for S. aureus infection (Aim 1); define the mechanism by which LukAB kills human phagocytes (Aim 2); and delineate the contribution of LukAB variants to the pathogenesis of other S. aureus clones (Aim 3). To accomplish these Aims, we propose to employ a multidisciplinary approach that combines molecular biology, genetics, cellular immunology, whole genome screens, and biochemistry, together with ex vivo and in vivo infection models. Understanding the molecular details of how LukAB mediates targeting and killing of phagocytes will provide insight into how S. aureus bi-component pore-forming toxins kill host cells and the importance of these toxins to S. aureus pathogenesis.