Assembly of the envelope of Bacillus anthracis vegetative forms

炭疽杆菌营养体包膜的组装

• 批准号: 9025674
• 负责人: Justin Mark Lunderberg
• 金额: $ 4.29万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9025674
• 关键词: Address; Aerobic; Affect; Aluminum Hydroxide; Animal Model; Anthrax Vaccines; Anthrax disease; Antibodies; Antigens; Architecture; Attenuated; Bacillus anthracis; Bacteria; Binding; Biochemical; Cell Wall; Communicable Diseases; Country; Cutaneous; Defect; Deposition; Disease; Domestic Animals; Electron Microscopy; Fractionation; Gastrointestinal tract structure; Gene-Modified; Genes; Genetic; Germination; Glutamic Acid; Human; Immune response; Immunity; Immunofluorescence Microscopy; In Vitro; Infectious Diseases Research; Knowledge; Lesion; Libraries; Life; Link; Mammals; Measures; Microscopy; Molecular; Molecular Genetics; Oligosaccharides; Pathogenesis; Peptidoglycan; Plasmids; Polysaccharides; Proteins; Reproduction spores; Research; Research Training; Secondary to; Structure; Structure of respiratory epithelium; Students; Tertiary Protein Structure; Toxin; United States; Vaccines; X-Ray Crystallography; anthrax lethal factor; capsule; career; gene product; genetic analysis; in vivo; mutant; pathogen; prevent; public health relevance; uptake

DESCRIPTION (provided by applicant): Bacillus anthracis is the causative agent of anthrax, a zoonotic disease that is transmitted by uptake of infectious spores. Germination of spores and massive expansion of the resulting vegetative forms precipitate the rapidly lethal disease anthrax, which affects most mammals including humans. B. anthracis has served as a model organism for infectious diseases and was used to first demonstrate that bacteria represent the causative agents of infectious diseases. Further, live-attenuated spore vaccines (LSVs) were used for the first demonstration that infected hosts can mount immune responses protective against wild-type B. anthracis. One of these LSVs, B. anthracis strain Sterne (pXO1+, pXO2-) lacks the pXO2 plasmid responsible for expression of the poly-D-γ-glutamic acid capsule (PDGA) and is used globally to prevent anthrax disease in domesticated animals. Importantly, the correlate of LSV-induced anthrax protective immunity is not yet known, however it is appreciated that LSV-derived opsonophagocytic antibodies promote clearance of the pathogen and sterilizing immunity. In the United States, AVA (BioThraxTM), a precipitate of Sterne-type culture supernatants adsorbed to aluminum hydroxide, is used as the anthrax vaccine for humans. AVA provides only partial protection in several animal models and the vaccine does not confer sterilizing immunity. AVA's correlate for protection, antibodies against the lethal toxi component protective antigen (PagA), neutralize the toxin but cannot promote opsonophagocytic clearance of the pathogen. Here we seek to address a key unanswered question for the field of bacterial pathogenesis: what is the correlate of protective immunity derived from LSVs? Obviously, the PDGA capsule can be ruled out, because the Sterne strain does not elaborate capsule. Our current appreciation of the envelope of vegetative forms implicates two main envelope structures as candidates, the secondary cell wall polysaccharide (SCWP) and the S-layer. To evaluate the contributions of the SCWP and the S-layer as protective antigens towards anthrax pathogenesis and protective immunity requires the molecular genetic analysis of the pathogen. We have shown that the SLH domain of 2 S-layer proteins (Sap and EA1) and 22 S-layer associated proteins (BslA-T) binds to the SCWP when it is pyruvylated via the csaB gene product and linked to the peptidoglycan of B. anthracis. Unliked pagA, both csaB and bslA are required for anthrax pathogenesis, however the genes that enable synthesis and assembly of the SCWP and its associated S-layer are not yet known. The knowledge gap is addressed in this proposal, which will explore the biochemical underpinnings of ordered S-layer and S-layer associated protein assembly on the SCWP.

描述（由申请人提供）：炭疽杆菌是炭疽病的病原体，炭疽病是一种人畜共患疾病，通过孢子的萌发和由此产生的营养体的大量繁殖而引发迅速致命的炭疽病，影响大多数哺乳动物。包括人类在内的炭疽芽孢杆菌已成为传染病的模型生物，并被用来首先证明细菌是病原体。此外，减毒活孢子疫苗（LSV）首次被证明受感染的宿主可以针对野生型炭疽芽孢杆菌产生免疫保护反应，其中一种LSV，炭疽芽孢杆菌斯特恩菌株（pXO1+，pXO2）。 -) 缺乏负责表达聚-D-γ-谷氨酸胶囊 (PDGA) 的 pXO2 质粒，在全球范围内用于预防炭疽病重要的是，LSV 诱导的炭疽保护性免疫的相关性尚不清楚，但人们认识到 LSV 衍生的调理吞噬抗体可促进病原体的清除和灭菌免疫。吸附到氢氧化铝上的斯特恩型培养物上清液沉淀物用作人类炭疽疫苗，AVA 在几种动物模型中仅提供部分保护。疫苗不能消除与保护相关的免疫力，针对致命毒素成分保护性抗原（PagA）的抗体可以中和毒素，但不能促进调理细胞清除病原体。细菌发病机制：LSV 产生的保护性免疫的相关性是什么？显然，可以排除 PDGA 荚膜，因为 Sterne 菌株没有详细说明我们目前对荚膜的认识。植物形式涉及两个主要的被膜结构作为候选者，即次生细胞壁多糖 (SCWP) 和 S 层。要评估 SCWP 和 S 层作为保护性抗原对炭疽发病机制和保护性免疫的贡献，需要进行分子遗传学分析。我们已经证明，当 2 个 S 层蛋白（Sap 和 EA1）和 22 个 S 层相关蛋白（BslA-T）的 SLH 结构域与 SCWP 结合时，它通过 csaB 基因产物被丙酮酸化，并与炭疽芽孢杆菌的肽聚糖连接，与 pagA 不同，csaB 和 bslA 都是炭疽发病机制所必需的，但是能够合成和组装 SCWP 及其相关 S 层的基因则不是必需的。该提案解决了已知的知识空白，该提案将探索 SCWP 上有序 S 层和 S 层相关蛋白质组装的生化基础。