Conjugate-induced Polysaccharide Antibodies

缀合物诱导的多糖抗体

• 批准号: 6992837
• 负责人: SHOUSUN C SZU
• 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/6992837
• 关键词: Campylobacter; China; Escherichia coli 0157:H7; Salmonella; Vibrio cholerae; active immunization; adult human (21+); bacterial antigens; bacterial polysaccharides; bacterial vaccines; bioterrorism /chemical warfare; children; clinical trial phase III; clinical trials; genetic strain; gram negative bacteria; human subject; human therapy evaluation; immunoconjugates; laboratory mouse; lipopolysaccharides; patient oriented research; preschool child (1-5); southeast Asia; vaccine development; vaccine evaluation

Surface polysaccharides of Gram-negative enteric pathogens, in the form of capsule or lipopolysaccharide, are both essential virulence factors and protective antigens. The immunogenicity of these polysaccharides were enhanced by binding to carrier proteins. Sequential clinical studies in adults and in children in Vietnam, an area with a high attack rate of typhoid, showed that the capsular polysaccharide (Vi) conjugates bound to the recombinant Pseudomonas aeruginosa exoprotein A (rEPA) elicited high responses against typhi. In a Phase III trial, About 12,000 2-5 years old children injected with the conjugate vaccine showed no significant side reaction. The efficacy of Vi-rEPA was 89% after 48 months surveillance. Chidren in the pacebo group were given the conjugate vaccine 2.5 years later. A dosage study in Northern Vietnam was conducted in children 2-5 years old. Results showed there was a dose dependent antibody response. The 25 microgram dose gave the highest response, followed by 12.5 microgram dose. There is no statistical significance between the two dosages. Children injected with 5 microgram of conjugate polysaccharide,however, had significantly lower Vi antibody levels than those received higher dosages. Salmonella paratyphi A, the second most common cause of enteric fever in Southeast Asia, conjugate vaccine was found to be safe and immunogenic in adults, teenagers and then 2-4 year old children. A careful re-examination of the conjugate vaccines of S. paratyphi A indicated that the O-acetyl content of the conjugate vaccine is directly related to the immunogenicity of the conjugate vaccine. In southeast China, cases of paratyphi A has exceeded those of typhi. A phase III clinical trial is planned. Escherichia coli O157, an emerging pathogen, causes hemolytic uremic syndrome in young children. Phase 1 study of E. coli O157 O-specific polysaccharide-rEPA conjugate demonstrated safety and immunogenicity in adult volunteers. The phase II study of E. coli O157 conjugate, 55 children 2-5 years old children were recruited. Children injected once or twice showed that the vaccine was safe. Immunogenicity data showed 98% children responded with greater than 4 fold rise of anti-LPS IgG 6 months after the first injection. There was no booster response in children receiving a second dose 6 weeks after the first injection. Non-toxic shiga toxin I and II are purified from mutant E. coli O157 and will be conjugated with O-specific polysaccharide for a bivalent vaccine. The major reservoir of E.coli O157 is cattle. LPS-protein conjugate showed to be immunogenic in cattle and a challenge study showed an inversed correlation between the serum anti-LPS IgG and the level of colonization of E. coli O157 at rectal. Vibrio cholera O1 and O139 are the major sero types in cholera infections. Conjugates synthesized with capsular polysaccharide of O139 and O-specific polysaccharide of LPS of O1 elicited vibriocidal antibodies in mice. Detoxified LPS from both Inaba and Ogawa serotypes have been used as a base for conjugate vaccine. In animal study, the conjugates elicited higher antibody level than LPS alone. A chemical synthesized O-specific polysaccharide for Ogawa will be prepared and conjugated to protein carrier. The immunogenicity of cholera vaccine prepared with naturally purified or chemically synthesized O-specific polysaccharide will be compared in clinical studies. One of the most common Salmonella infection in developed country is Salmonella typhimurium. Antibiotic resistant strains have been common in disease isolates. We have compared the O-specific polysaccharide structure of the most common and antibiotic resistant strains. The O-acetyl group on the abequose is found to be a major antigenic site and an immunodominant determinant. Strains that are O-acetyl positive reacted with antibodies from O-acetyl negative strains poorly. Selection of strains for vaccine preparation will therefore rely on the epidemiology survey and bacteriology identification. Campylobacter jejuli infection is one of the most common enteric infection in the US and around the world. The most common type in US is type 2. Campylobacter is microaerophilic and fermentation in liquid mmedia has been difficult. Various media and fermentation conditions was studied and growth in liquid media were succeeded. Chemical analysis showed that the surface polysaccharide contains keto groups and does not contain colominic acid. From the size and the staining properties, we concluded that the polysaccharide is an oligo LPS. The conjugate prepared with LPS or deacetylated LPS were immunogenic and showed bactercidal activity in the presence of complement.

革兰氏阴性肠道病原体的表面多糖以胶囊或脂多糖的形式是必需的毒力因子和保护性抗原。通过与载体蛋白结合来增强这些多糖的免疫原性。越南的成年人和儿童的顺序临床研究（一个伤寒率高的地区）表明，与重组假单胞菌的铜绿假单胞菌相结合的囊囊多糖（VI）结合物A（repa）对Typhi的高反应产生了高反应。在III期试验中，注射结合疫苗的约12,000名2-5岁儿童没有明显的副反应。在监视48个月后，VI-REPA的功效为89％。 Pacebo组中的Chidren 2。5年后，给予共轭疫苗。在越南北部进行了一项剂量研究，对2-5岁的儿童进行了。结果表明存在剂量依赖性抗体反应。 25微克剂量给出了最高的响应，其次是12.5微克剂量。两种剂量之间没有统计学意义。但是，注射5微克共轭多糖的儿童的VI抗体水平明显低于接受剂量较高的抗体水平。沙门氏菌帕托菲A是东南亚肠发烧的第二大最常见原因，在成年人，青少年和2-4岁的孩子中发现结合疫苗是安全且免疫原性的。对副链球菌的结合疫苗进行了仔细的重新检查，表明结合疫苗的O-乙酰含量与结合疫苗的免疫原性直接相关。在中国东南部，帕拉托菲A的病例超出了Typhi。计划进行III期临床试验。大肠杆菌O157是一种新兴的病原体，会导致幼儿溶血性尿毒症综合征。大肠杆菌O157 O特异性多糖 - repa偶联物的1阶段研究表明了成人志愿者的安全性和免疫原性。大肠杆菌O157结合的II期研究，招募了55名2-5岁儿童的儿童。注射一次或两次的儿童表明该疫苗是安全的。免疫原性数据显示，在第一次注射6个月后，抗LPS IgG的4倍升高了98％的儿童。第一次注射后6周，接受第二剂剂量的儿童没有助推器反应。非毒性志贺毒素I和II从突变的大肠杆菌O157纯化，并将与O特异性多糖共轭用于双价疫苗。 E.Coli O157的主要水库是牛。 LPS蛋白结合物显示在牛中具有免疫原性，一项挑战研究表明，血清抗LPS IgG与直肠上大肠杆菌O157的定殖水平之间存在反相相关性。弧菌O1和O139是霍乱感染中的主要血清类型。与O1的O1的O1的O139和O特异性多糖合成的O1的O1的O1多糖合成。来自Inaba和Ogawa血清型的排毒LP已被用作结合疫苗的基础。在动物研究中，偶联物引起的抗体水平高于单独的LPS。将制备化学合成的OGawa的O特异性多糖，并将其与蛋白质载体共轭。在临床研究中，将比较用天然纯化或化学合成的O特异性多糖制备的霍乱疫苗的免疫原性。发达国家最常见的沙门氏菌感染之一是鼠伤寒沙门氏菌。抗生素抗性菌株在疾病分离株中很常见。我们已经比较了最常见和抗生素抗性菌株的O特异性多糖结构。发现Abquose上的O-乙酰基是主要的抗原部位，是免疫主导的决定因素。 O-乙酰阳性的菌株与o-乙酰基负菌株的抗体反应不佳。因此，选择疫苗制备菌株将依赖于流行病学调查和细菌学鉴定。弯曲杆菌的壁式感染是美国和世界各地最常见的肠道感染之一。在美国，最常见的类型是2型。弯曲杆菌是微粒细胞的，液态mmedia中的发酵很困难。研究了各种培养基和发酵条件，并在液体培养基中的增长成功。化学分析表明，表面多糖含有酮基，不含成成醇酸。从大小和染色特性中，我们得出结论，多糖是寡糖。用LPS制备或脱乙酰化LP制备的结合物具有免疫原性，并在补体存在下显示出杀菌活性。