HUMAN IMMUNE RESPONSE TO POLYSACCHARIDE-PROTEIN CONJUGATE VACCINES

多糖蛋白结合疫苗的人体免疫反应

• 批准号: 6432559
• 负责人: RACHEL SCHNEERSON
• 金额: --
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 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/6432559
• 关键词: Shigella vaccines; Streptococcus vaccine; active immunization; bacterial polysaccharides; bactericidal immunity; chronic renal failure; clinical research; clinical trial phase I; drug screening /evaluation; human subject; immunoconjugates; immunoglobulins; infant human (0-1 year); laboratory mouse; sickle cell anemia; tetanus toxoid

Surface polysaccharides of pathogenic bacteria, including capsular polysaccharides (CPS) or lipopolysaccharides (LPS), may serve both as essential virulence factors and as protective antigens. The age-related and T-cell independent immunogenicity of CPS limit their use as vaccines especially in infants and young children. LPS are too toxic to administered. Accordingly, their O-specific polysaccharide (O-SP), that share the virulence promoting and protectiveness of CPS, must be purified: O-SP are too small to be immunogenic (haptens). Covalently binding CPS or of O-SP to medically-useful proteins to form conjugates both increases their immunogenicity and confers T-cell dependence to these saccharides.The O-SP of Shigella sonnei and of Shigella flexneri 2a were bound to bacterial toxoids. In adults and then in 4-7 year-olds, both conjugates were safe and induced statistically significant and long-lived rises of IgG antibodies to the homologous LPS. Similar, though lesser rises of IgM and IgG anti-LPS were also induced. The levels of serum IgG anti-LPS were equal to or greater that those in recruits that recovered from shigellosis. Re-injection of S. flexneri 2a conjugate induced a booster response in the recruits. A Phase 3 trial showed that one injection of S. sonnei O-SP, bound to a non-toxic recombinant Pseudomonas aeruginosa exoprotein A (rEPA) protected army recruits against outbreaks with this pathogen. Importantly, there was a statistically-significant correlation between the levels of serum IgG anti-LPS and the efficacy of the conjugate. Two methods were developed that increased the immunogenicity of the Shigella conjugates in mice. First another carrier protein, a genetically-inactivated Corynebacterium diphtheriae toxin (CRM9) was a superior carrier for S. sonnei O-SP. Second treatment of rEPA with succinic anhydride, a non-toxic mild akylating agent that converts amino groups of proteins to carboxyls, increased the immunogenicity of S. flexneri 2a O-SP. A phase 1 study of these improved Shigella conjugates confirmed their immunogenicityand these new products are being evaluated for their clinical efficacy in a Phase 3 trial in Israel. In collaboration with the Lanzhou Vaccine Institute and Provincial Medical Center in Henan,China, a clinical trial of these two conjugates is being planned.A double mutant of Bordetella pertussis, producing a genetically-inactivated toxin and deficient in FHA synthesis was developed. Effort is directed towards increasing production of this B. pertussis strain as a more easily purified pertussis toxin for a monocomponent vaccine and as a carrier protein for pneumococcal type 14 CPS.Clostridium difficile is a major cause of hospital-acquired diarrhea following antibiotic usage: the diarrhea is mediated by two exotoxins, A and B. Toxin A, considered to be the major toxin, in its extreme form will cause pseudomembranous colitis. A genetically-derived toxin mutant (rARU) induces both antitoxin and protects animals from infection with C. difficile. The solubility of rARU improved its solubility and did not detectable affects its reaction with antiserum. Techniques to prepare the mutant toxins A and B for clinical use have been worked out. Three polysaccharide of varying composition, pneumococcus type 14, Escherichia coli K1 and S. flexneri 2a were conjugated to succinylated rARU. The resultant conjugates induced high levels of both anti-polysaccharide and antitoxin. Clinical evaluation of these conjugates, designed to protect two diseases, is underway.

病原菌表面多糖，包括衣壳多糖(CPS)或脂多糖(LPS)，既可作为基本毒力因子，又可作为保护性抗原。CPS的年龄相关和T细胞非依赖性免疫原性限制了其作为疫苗的使用，特别是在婴幼儿中。脂蛋白毒性太大，无法实施管理。因此，它们的O-特异性多糖(O-SP)具有CPS的毒力促进和保护作用，必须进行纯化：O-SP太小而不能产生免疫原性(半抗原)。将CPS或O-SP共价结合到医学上有用的蛋白质上形成偶联物，既提高了它们的免疫原性，又使这些糖具有T细胞依赖性。宋内氏志贺氏菌和福氏2a志贺菌的O-SP与细菌类毒素结合。在成人和4-7岁儿童中，这两种结合物都是安全的，并诱导了具有统计学意义的同源内毒素抗体的长期升高。免疫球蛋白IgM和抗脂多糖抗体的升高幅度较小，但与此相似。新兵血清免疫球蛋白抗体水平与志贺氏菌病痊愈新兵相当或更高。重新注射福氏2a结合菌在新兵中诱导了增强反应。3期试验表明，一次注射宋内氏链球菌O-SP，与无毒的重组铜绿假单胞菌外蛋白A(REPA)结合，可保护新兵免受这种病原体的爆发。重要的是，血清中抗内毒素抗体的水平与结合物的疗效之间存在统计学上的显著相关性。建立了两种提高志贺氏菌结合物在小鼠体内免疫原性的方法。首先，另一种载体蛋白，一种基因灭活的白喉棒状杆菌毒素(CRM9)是宋内氏葡萄球菌O-SP的优越载体。用琥珀酸酐处理REPA，一种无毒的温和的烷基化试剂，将蛋白质的氨基转化为羧基，增加了福氏2a志贺氏菌O-SP的免疫原性。对这些改进的志贺氏菌结合物的第一阶段研究证实了它们的免疫原性，这些新产品正在以色列的第三阶段试验中评估其临床疗效。与兰州市疫苗研究所和河南省医学中心中国合作，正计划对这两种结合物进行临床试验。培育出一种产生遗传灭活毒素且FHA合成不足的百日咳杆菌双突变株。努力提高这种百日咳杆菌的产量，将其作为一种更容易提纯的百日咳毒素用于单组分疫苗，并作为14型肺炎链球菌的载体蛋白。艰难梭菌是抗生素使用后医院获得性腹泻的主要原因：腹泻由两种外毒素A和B介导：A毒素被认为是主要毒素，其极端形式会引起伪膜性结肠炎。一种基因衍生的毒素突变体(RARU)既能诱导抗毒素，又能保护动物免受艰难梭菌的感染。RARU的溶解度提高了其溶解度，对其与抗血清的反应无明显影响。制备突变毒素A和B用于临床的技术已经制定出来。将肺炎球菌14型、大肠杆菌K1和福氏2a菌三种不同组成的多糖与琥珀酸化的RARU偶联。生成的结合物诱导了高水平的抗多糖和抗毒素。这些旨在保护两种疾病的结合物的临床评估正在进行中。