Novel Antimicrobials Targeting Bacterial Type IV Secretion Systems

描述(由申请人提供)：抗生素耐药性的日益流行正在损害我们治疗感染的能力。因此，这项应用的广泛、长期的目标是开发和建立针对病原体宿主相互作用的新型疗法的原理证明。许多细菌病原体使用特殊的分泌系统将毒力因子注入宿主细胞。这些系统对毒力是绝对必要的，因此提供了一个有希望的治疗靶点。这项提议的目的是建立IV型分泌系统(T4SS)--这类注射器械的主要类别之一--作为抗菌治疗的目标。我们最近使用模式病原体嗜肺军团菌完成了对23.5万个化合物文库的高通量筛选，以确定T4SS的小分子抑制剂。在这里，我们建议跟进从这次筛查工作中获得的初步数据，并有三个具体目标。在第一个实验中，我们建议对以前鉴定的、强筛选的HITS进行表征，以确认特异性，定义效力，并表征嗜肺性乳杆菌、伯氏柯克斯体和一系列更远亲的依赖T4SS的病原体的活性谱。在第二个研究中，将使用迭代结构-活性关系研究来确定具有增强的药理潜力的类似物。在第三项研究中，选定的小分子抑制剂的活性将在感染嗜肺性乳杆菌、伯氏支原体和巴尔通体的小鼠模型中进行体内表征。综上所述，这些实验将为T4SS疗法及其作为一种新的人类疗法的潜在用途奠定理论基础。

DESCRIPTION (provided by applicant): The increasing prevalence of antibiotic resistance is compromising our ability to treat infection. Therefore, this application's broad, long-term objective is to develop and establish proof of principle for a new class of therapeutics targeting pathogen host interaction. Many bacterial pathogens use specialized secretion systems to inject virulence factors into host cells. These systems are absolutely required for virulence and therefore offer a promising therapeutic target. The aim of this proposal is to establish type IV secretion systems (T4SS) -- one of the major classes of such injection apparatuses - as a target for antimicrobial therapy. We recently completed a high throughput screen of a 235,000 compound library using the model pathogen, Legionella pneumophila, in order to identify small molecule inhibitors of T4SS. Here, we propose to follow up on preliminary data obtained from this screening effort with three specific aims. In the first, experiments are proposed to characterize previously identified, strong screening hits in order to confirm specificity, define potency, and characterize activity spectrum in L. pneumophila, Coxiella burnetii and a series of more distantly related T4SS-dependent pathogens. In the second, iterative structure-activity relationship studies will be used to identify analogues with the enhanced pharmacological potential. In the third, the activity of select small molecule inhibitors will be characterized in ivo in murine models of infection with L. pneumophila, C. burnetii, and Bartonella. Taken together these experiments should establish the theoretical basis for T4SS therapy and its potential use as a new human therapeutic.