Immune Response To Polysaccharide-protein Conjugate Vacc

病原菌的表面多糖，包括荚膜多糖（CPS）或脂多糖（LPS），既是必需的毒力因子，也是保护性抗原。CPS的年龄相关性和T细胞非依赖性免疫原性限制了其作为疫苗的使用，特别是在婴儿和幼儿中。LPS毒性太大，无法给药。因此，它们的O-特异性多糖（O-SP），共享CPS的毒力促进和保护性，必须纯化：O-SP太小而不具有免疫原性（半抗原）。CPS或O-SP与医学上有用的蛋白质共价结合以形成缀合物既增加了它们的免疫原性又赋予T细胞对这些抗体的依赖性。 宋内志贺菌和福氏志贺菌2a的O-SP与细菌类毒素结合。在成人中，然后在4 - 7岁的孩子，这两种共轭物是安全的，并诱导统计学显着和长期的上升IgG抗体同源LPS。类似地，也诱导了IgM和IgA抗LPS的较小升高。再注射S.弗氏2A缀合物在新兵和4 - 7岁儿童中诱导加强应答。一项3期试验表明，一次注射S。Sonnei O-SP结合到无毒的重组铜绿假单胞菌胞外蛋白A（rEPA）上，保护新兵免受这种病原体的爆发。重要的是，血清IgG抗LPS水平与缀合物的功效之间存在显著相关性。开发了两种方法来增加志贺氏菌缀合物在小鼠中的免疫原性：另一种载体蛋白，遗传灭活的白喉棒状杆菌毒素（CRM 9）是志贺氏菌的上级载体。Sonnei O-SP和用琥珀酸酐处理rEPA，琥珀酸酐是一种无毒的温和烷基化剂，可将蛋白质的氨基转化为羧基，增加了S.这些志贺氏菌缀合物在成人中的1期研究证实了它们的安全性和免疫原性;改进的免疫原性不如在小鼠中显著。一项针对1 - 4岁儿童的II期研究显示，新福氏志贺菌2a结合物的免疫原性有所改善，但宋内志贺菌结合物的免疫原性较低。一项关于改良福氏志贺菌2a和原始志贺菌的3期研究。Sonnei缀合物正在制备中。与中国河南省兰州疫苗研究所和省医学中心合作，正在计划对这两种结合物进行临床试验。 为了研究同时施用交叉反应沿着同源CPS是否比单独使用同源CPS具有优势，通过常规方法分离了短小芽孢杆菌SH 18的细胞壁多糖（PS），其被报道与流感嗜血杆菌B型（Hi B）的CPS交叉反应，并且其在体外被分离。用GC-MS分析了其结构，确定其含有甘油、核糖醇和2-乙酰氨基-2-脱氧葡萄糖（摩尔比为0.2：1.0：0.2），磷酸根含量为17%。除与抗Hib有交叉反应外，还与抗表皮葡萄球菌有交叉反应。研究了制备该PS的缀合物的方法。A群脑膜炎奈瑟菌引起地方性和流行性脑膜炎，特别是在非洲脑膜炎带。有效和可用的CPS疫苗未得到充分利用。为了进一步改善？由于它的免疫原性，正如对其他CPS所做的那样，将其结合到载体蛋白的方法正在研究中。 研制了一种百日咳博德特氏菌双突变株，它能产生一种遗传灭活毒素并缺乏FHA合成。努力的方向是增加该B的产量。百日咳菌株作为更容易纯化的百日咳毒素用于单组分疫苗和作为肺炎球菌14型CPS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。毒素A，被认为是主要的毒素，在极端的形式会导致伪膜性结肠炎。一种遗传衍生毒素突变体（rARU）诱导抗毒素并保护动物免受C.很难琥珀酰化的rARU提高了其溶解性，并没有检测到影响其抗原性。制备突变毒素A供临床使用的技术已经制定出来。三种不同组成的多糖，肺炎球菌14型，大肠杆菌K1和S。福氏2a与琥珀酰化的rARU缀合。所得缀合物诱导高水平的抗多糖和抗毒素。用于临床评估的毒素A缀合物的制备正在进行中。 莱姆病的病原体是伯氏疏螺旋体（Borrelia burgdorferi），它是一种通过感染的硬蜱叮咬传播的螺旋体。目前已有一种蛋白质疫苗，但对12岁以下儿童无效。LPS在其他螺旋体中也有描述，但它存在于B中。Burgdorferi一直在争论。到目前为止，我们还不能确认它的存在。对LPS的搜索揭示了一种独特的糖脂，其由甘油和半乳糖作为碳水化合物部分组成。有证据表明，这种糖脂是表面暴露的，注射在完全弗氏佐剂中，它诱导特异性抗体。

Surface polysaccharides of pathogenic bacteria, including capsular polysaccharides (CPS) or lipopolysaccharides (LPS), 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 be 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). Covalent binding of 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 IgA anti-LPS were also induced. Re-injection of S. flexneri 2a conjugate induced a booster response in the recruits and the 4-7 years old. 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: another carrier protein, a genetically-inactivated Corynebacterium diphtheriae toxin (CRM9) was a superior carrier for S. sonnei O-SP and 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 in adults of these Shigella conjugates confirmed their safety and immunogenicity; the improved immunogenicity was less marked than in mice. A phase 2 study in 1-4 years old showed an improved immunogenicity of the new S.flexneri 2a conjugate but lesser immunogenicity of the S.sonnei conjugate. A phase 3 study of the modified S.flexneri 2a and the original S. sonnei conjugates are in preparation. In collaboration with the Lanzhou Vaccine Institute and Provincial Medical Center in Henan, China, a clinical trial of these two conjugates is being planned. To investigate if concurrent administration of a cross-reacting along with a homologous CPS has an advantage over the use of the homologous CPS alone, the cell wall polysaccharide (PS) of Bacillus pumilus, SH18, reported to cross react with the CPS of haemophilus influenzae type b (Hib), was isolated by conventional methods and it?s structure investigated using GC-MS. It was shown to contain glycerol, ribitol and 2-acetamido-2-deoxyglucose in a molar ratio of 0.2:1.0:0.2 and 17% phosphate. Besides with the anti Hib it cross reacted with anti Staphilococcus epidermidis. Methods to prepare a conjugate of this PS are investigated. Neisseria meningitidis group A causes endemic and epidemic meningitis, notably in the meningitis belt of Africa. A CPS vaccine , effective and available, is underutilized. To further improve it?s immunogenicity, as was done for other CPS, methods of binding it to a carrier protein are being investigated. 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 the extreme form will cause pseudomembranous colitis. A genetically-derived toxin mutant (rARU) induces both antitoxin and protects animals from infection with C. difficile. The succinylation of rARU improved its solubility and did not detectably affects its antigenicity. Techniques to prepare the mutant toxins A 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. Preparation of toxin A conjugates for clinical evaluation is underway. Borrelia burgdorferi, a spirochete transmitted though the bite of infected Ixodes ticks, is the etiologic agent of Lyme disease. A protein vaccine against it is available but is not effective below the age of 12 years. LPS has been described in other spirochetes but it's presence in B. burgdorferi has been debated. So far we have not been able to confirm it's presence. The search for LPS revealed a unique glycolipid cosisting of glycerol and galactose as the carbohydrate moiety. There is evidence that this glycolipid is surface exposed Injected in complete Freund's adjuvant it induced specific antibodies.