IMMUNE RESPONSE TO GROUP B MENINGOCOCCAL CAPSULAR POLYSACCHARIDE

对 B 组脑膜炎球菌荚膜多糖的免疫反应

• 批准号: 3770275
• 负责人: S DEVI
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3770275
• 关键词: Neisseria meningitidis; Neisseria meningitidis vaccine; active immunization; antibacterial antibody; antibody formation; antibody specificity; antigen antibody reaction; bacterial capsules; bacterial polysaccharides; bactericidal immunity; carbohydrate structure; chemical structure function; immunoconjugates; immunoglobulin G; immunoglobulin M; immunomodulators; laboratory mouse; monoclonal antibody

Alpha (2->8) polysialic acid (PSA) forms the capsular polysaccharide (CPS) of group B meningococci (GBM), Escherichia coli K1 (ECK1) and a part of E. coli K92 CPS and is associated with pathogenesis and protection in GBM and ECK1 infections. PSA is a poorly immunogenic, conformationally complex T-independent antigen. To evaluate the complexity of immunodeterminants expressed on this CPS and to identify epitope(s) with biologic functions, two panels of murine monoclonal antibodies (mAbs) were generated and characterized by immunizing BALB/c mice with GBPS-OMP (fusion A) or OAc+K1-OMP (fusion B) conjugate vaccine. Fusion A yielded 23 mAbs representative of IgM class and all subclasses of IgG and showed 6 different microspecificities as examined by their differential binding to native and chemically modified PSA attached to a solid phase by various methods; fusion B yielded 11 mAbs with microheterogenous specificities. Confirmatory competitive inhibition ELISA revealed that the mAbs recognized a mosaic of immunodeterminants on OAc+K1PS and GBPS. Two mAbs induced by OAc+K1-OMP conjugate were directed to O-acetyl epitope and the rest reacted with OAc+K1 and only with GBPS attached to solid phase in certain forms. MAbs generated by the GBPS-OMP conjugate mostly recognized an epitope shared by both GBPS and OAc+K1PS; one also recognized an epitope on ECK92. IgG1 mAbs and those with O-acetyl specificity were non-bactericidal to GBM in presence of rabbit complement, whereas other mAbs were bactericidal. No correlation could be established between the microspecificity of mAbs and their in vitro bactericidal activity. Conjugation and complexation of PSA with proteins appear to improve the accessibility of certain epitopes for mAb binding. Thus the methods by which antigen was coated on solid phase had a great impact on the binding specificity and intensity of mAbs. GBPS antibodies from group B meningococcal patients, carriers and vaccinees also showed similar microheterogeneity in epitope binding. Immunogenicity tests done in mice revealed that both GBPS-OMP and OAc+K1-OMP conjugates were immunogenic and produced both IgG and IgM capsular antibodies. The adjuvant MPL significantly enhanced the capsular antibody response. Antibodies induced by OAc+K1-OMP conjugate were mostly O-acetyl epitope-specific. Temperature dependence in antigen binding and various other properties of conjugate-induced polyclonal GBPS antibodies are being evaluated.

α(2-gt；8)聚唾液酸(PSA)形成胶囊多糖(CPS) B群脑膜炎双球菌(GBM)、大肠埃希菌K1(ECK1)和部分E。 ColiK92 CPS与GBM的发病机制和保护作用有关 ECK1感染。PSA是一种免疫原性很差的构象复合体 T非依赖性抗原。评估免疫决定簇的复杂性 在此CPS上表达并鉴定具有生物学功能的表位(S)， 产生了两组小鼠单抗(MAbb)，并 其特征是用Gbps-OMP(融合A)或BALB/c小鼠免疫 OAC+K1-OMP(融合B)结合疫苗。融合A产生23株单抗 代表免疫球蛋白M类和所有免疫球蛋白亚类，并显示6 不同的微特异性，通过它们与不同的结合 天然的和化学修饰的PSA通过各种不同的方式连接到固相上 方法：融合B产生11株具有微异质性的单抗。 验证性竞争抑制酶联免疫吸附试验结果显示，mAbs可识别 OAC+K1PS和GBP上的免疫决定簇的马赛克。日本血吸虫诱导的两株单抗 OAc+K1-OMP偶联物被定向到O-乙酰表位，其余的反应 具有OAc+K1，并且仅具有以特定形式附着到固相上的Gbps。 Gbps-OMP结合物产生的单抗主要识别一个表位 由GBP和OAC+K1PS所共有；ECK92上的一个表位也被识别。 IgG1单抗和O-乙酰特异性单抗对GBM无杀菌作用 在兔补体存在的情况下，而其他单抗具有杀菌作用。不是 单抗和单抗的微特异性之间可以建立相关性 它们的体外杀菌活性。PSA的偶联和络合作用 与蛋白质似乎改善了某些表位的可及性 单抗结合。因此，将抗原包被在固相上的方法 对单抗的结合特异性和结合强度有很大影响。Gbps B组脑膜炎球菌患者、携带者和接种者的抗体也 在表位结合上表现出相似的微观异质性。 在小鼠身上进行的免疫原性测试表明，Gbps-OMP和 OAc+K1-OMP结合物具有免疫原性，可同时产生免疫球蛋白和免疫球蛋白 囊膜抗体。佐剂MPL显著增强了囊膜 抗体反应。OAC+K1-OMP结合物诱导的抗体 O-乙酰表位特异性。抗原结合中的温度依赖性和 结合物诱导的多克隆GBP抗体的各种其他性质 正在接受评估。