Studies of the capsular-like antigen of F. tularensis

土拉弗拉菌荚膜样抗原的研究

• 批准号: 8305635
• 负责人: Michael A. Apicella
• 金额: $ 40.98万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8305635
• 关键词: Active Immunization; Anabolism; Animal Model; Antibodies; Antigens; Bacteria; Biological; Biological Warfare; Cell Culture Techniques; Cells; Chemicals; Electron Microscopy; Francisella; Francisella tularensis; Gene Mutation; Genes; Homologous Gene; Immune response; Immunity; Infection; Investigation; Modeling; Morphology; Mus; Mutagenesis; Passive Immunization; Pathogenesis; Pathogenicity; Population; Production; Regulation; Respiratory Tract Infections; Role; Ruthenium Red; Site; Solid; Staining method; Stains; Structure; Surface; Virulence Factors; Work; base; capsule; genome database; immunogenicity; microbial; mutant; protective efficacy; protein transport; sugar; therapeutic development; vaccine candidate; weapons of mass destruction

Francisella tularensis is a class A bacterial select agent due to its extreme pathogenicity and potential use as a bioweapon. Early studies by Carlisle and Hood have indicated that F. tularensis produces a capsule-like material. Many bacteria produce capsules and the genes required to produce them encode proteins for transport, biosynthesis and regulation. Homologs of genes implicated in capsular biosynthesis are present in the Francisella genome database. Preliminary studies, using electron microscopy, indicate and confirm that a capsule-like material (CLM) surrounds F. tularensis. We can now isolate this material, free from Francisella LPS, based on chemical, chromatographic and immunochemical analysis. This material is loosely associated with the bacterial cell, is easily removed from the bacterial surface and is composed of a repeating tetrasaccharide repeat. Using transposon mutagenesis in F. tularensis Schu S4, we have identified a number of mutants with no or limited reactivity to our CLM specific antibody XE8. We have currently identified the site of insertion of 7 of these transposon mutants that have altered CLM expression that will serve as acapsular strains for the studies in this proposal. Based on these observations, we would pose the following hypotheses 1) Francisella tularensis expresses a capsular-like material that is important in pathogenesis and that we believe is a group 1 capsule; 2) Alteration of this capsule-like structure by mutations of the genes involved in biosynthesis and expression of CLM will alter pathogenicity of Francisella tularensis in cell culture models and in an animal model of respiratory infection; 3) Induction of an immune response targeted to the CLM will provide host immunity. The following specific aims will be used to resolve these hypotheses: 1) Characterization of the F. tularensis Schu S4 mutants that are defective in production of capsule-like material and 2) Characterization of the biological role of the P. tularensis Schu S4 capsule like material and 3) Study the immunogenicity and protective efficacy of passive and active immunization in murine models of Francisella infection

Francisella tularensis是A类细菌选择剂，因为其极端的致病性和潜在用作生物武器。卡莱尔（Carlisle）和胡德（Hood）的早期研究表明，tularensis会产生类似胶囊的材料。许多细菌产生胶囊，产生它们所需的基因编码蛋白质以进行运输，生物合成和调节。弗朗西斯菌基因组数据库中存在与囊囊生物合成有关的基因的同源物。使用电子显微镜的初步研究表明并确认胶囊样材料（CLM）围绕F. tularensis。现在，我们可以根据化学，色谱和免疫化学分析分离这种材料，而不受Francisella LPS的隔离。该材料与细菌细胞松散相关，很容易从细菌表面去除，并由重复的四糖重复组成。使用F. tularensis Schu S4中的转座子诱变，我们已经确定了许多对CLM特异性抗体XE8反应性无反应性的突变体。我们目前已经确定了这些转座子突变体中的7个插入部位，这些突变体改变了CLM表达，这将作为该提案中研究的交叉菌株。基于这些观察结果，我们将提出以下假设1）Francisella tularensis表达了一种类似囊状的材料，在发病机理中很重要，我们认为是1组胶囊； 2）通过在细胞培养模型和呼吸道感染的动物模型中，参与生物合成和CLM表达的基因的突变改变了这种胶囊样结构； 3）诱导针对CLM的免疫反应将提供宿主免疫。以下具体目的将用于解决这些假设：1）表征F. tularensis schu S4突变体在产生胶囊样材料时有缺陷的胶囊样材料和2）表征tularymensis schu s4囊的生物学作用，例如材料和3）研究的免疫和保护性效果。