EARLY ESTABLISHMENT STAGES OF ANTHRAX INFECTION

炭疽感染的早期阶段

• 批准号: 6534168
• 负责人: Philip C Hanna
• 金额: $ 18.95万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-15 至 2005-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6534168
• 关键词: Bacillus anthracis; anthrax; bacteria infection mechanism; bacterial genetics; disease /disorder model; laboratory mouse; life cycle

This proposal investigates the first hours of anthrax infections; in vivo germination of the Bacillus anthracis endospore, macrophage survival, growth and escape of the vegetative bacilli. Outside the host, endospores remain metabolically-dormant, preserving virulence even when exposed to harsh environmental conditions. Endospores are the anthrax contagion, entering the body where they are phagocytosed by regional macrophages. Endospores "sense" the new locale, germinate and outgrow to a vegetative state. Our preliminary data defined discrete mutants blocked at each of these steps. After escape, massive bactermia, toxemia and death ensues. Our data also indicate that anthrax endospores have unique in vivo sensory and signaling mechanisms for triggering germination. Germination occurs rapidly in cultured macrophages. Non-pathogenic Bacillus sp. endospores show no increased germination in macrophages. A B. anthracis transposon-mediated mutagenesis system allowed selection of individual endospore mutants incapable of germination in macrophages but fully capable of germination and outgrowth in bacterial media. Several unique classes of mutants were characterized. One such loci, named gerP (germination Plasmid), is located on the virulence (toxin) plasmid pXO1. Thus mutations in gerP eliminate host-specific germination but not general germination responses. The aims of this proposal are to: a. define and characterize the germination genes of B. anthracis and host chemical signals to determine their roles in the host- specific germination response; b. determine defined intracellular events and bacterial genes used by the vegetative bacilli allowing for survival and escape from the macrophage, and; c. understand the relevance of B. anthracis host-specific germination systems and early intracellular events in terms of pathogenesis in the murine model. Knowledge of these critical "establishment" stages of anthrax may provide targets for early intervention after exposure to anthrax endospores. Understanding this rapid and dramatic switch, from absolute metabolic dormancy of the endospore to growing virulent bacilli allows anthrax to be exploited as an effectual model for examining the earliest stages of bacterial infectious cycles.

这项建议调查炭疽感染的第一个小时，炭疽芽孢杆菌内生孢子的体内萌发，巨噬细胞的存活，生长和逃逸的营养杆菌。在宿主之外，内生孢子保持代谢休眠，即使暴露于恶劣的环境条件下也保持毒性。 内生孢子是炭疽的传染物，进入人体后被局部巨噬细胞吞噬。内生孢子“感觉”到新的位置，发芽并生长为营养状态。 我们的初步数据定义了在这些步骤中的每一个步骤中被阻断的离散突变体。 逃跑后，出现大面积的血吸虫病、毒血症和死亡。 我们的数据还表明，炭疽内生孢子有独特的体内感觉和信号机制，触发萌发。 在培养的巨噬细胞中迅速萌发。 非致病性芽孢杆菌内生孢子在巨噬细胞中未显示出增加的萌发。 A B。炭疽菌转座子介导的诱变系统允许选择不能在巨噬细胞中萌发但完全能够在细菌培养基中萌发和生长的单个内生孢子突变体。 几个独特的类别的突变体进行了表征。 一个这样的基因座，命名为gerP（萌发质粒），位于毒力（毒素）质粒pXO 1上。 因此，gerP突变消除主机特定的发芽，但不是一般的发芽反应。 本提案的目的是：a.确定和表征了B的发芽基因。炭疽菌和宿主化学信号，以确定它们在宿主特异性萌发反应中的作用; B.确定由所述营养杆菌使用的限定的细胞内事件和细菌基因，从而允许存活并从所述巨噬细胞逃逸，以及; c.理解B的相关性。炭疽宿主特异性发芽系统和早期细胞内事件的发病机制在小鼠模型。 这些关键的“建立”阶段的炭疽知识可能提供接触炭疽内生孢子后的早期干预目标。 了解这种快速而戏剧性的转变，从内生孢子的绝对代谢休眠到生长的毒性杆菌，可以将炭疽作为一种有效的模型来研究细菌感染周期的最早阶段。