Protein and Polysaccharide Conjugate Vaccines to enteric diseases

伤寒沙门氏菌（Vi）的荚膜多糖是一种获得许可的疫苗，但对5岁以下儿童的疗效有限。为了给年幼的儿童提供疫苗，将Vi与铜绿假单胞菌的重组外蛋白A（rEPA）缀合。在注射Vi-rEPA的2至5岁奥尔兹中，47个月时的有效性为89%。在301名越南婴儿中评价了在扩大免疫计划（EPI）中与常规疫苗同时接种的Vi-rEPA在2、4、6和12个月时的安全性和免疫原性。对照组接受Hib-TT +EPI或单独EPI。任何组均未发生严重不良事件。 Vi-rEPA组的GM IgG抗Vi水平显著高于对照组;末次注射后1个月90%的婴儿高于估计的保护水平。各组间白喉（DT）、破伤风（TT）类毒素和百日咳毒素IgG抗体水平无差异; Vi-rEPA适用于婴儿常规免疫。 与国际疫苗研究所和诺华全球健康研究所合作，将Vi与DT和TT等许可疫苗结合。 在小鼠中，这些缀合物引起与Vi-rEPA诱导的IgG抗Vi水平相似的IgG抗Vi水平。 甲型副伤寒沙门氏菌（SPA）是发展中国家肠道发热的第二大常见原因，通过摄入受感染者污染的食物或饮料传播。 在SPA爆发的调查中，通过测量SPA感染者（直肠拭子阳性个体）的血清抗LPS水平，确定了一名慢性携带者。与广西疾病预防控制中心合作，在高流行区开展了一项扩大调查，以筛查潜在的慢性携带者。 霍乱弧菌O 1仍然是印度次大陆和非洲的一个主要健康问题。现场研究表明，血清杀弧菌活性针对其LPS。在1期试验中，霍乱弧菌O-SP缀合物引发具有杀弧菌活性的IgG抗LPS。化学合成对应于O-SP的六聚体并将其缀合至TT。 在小鼠中，该缀合物引起比I期研究中使用的天然O-SP缀合物更高的杀弧菌活性。 研究了各种接头长度。 用十七聚体接头合成的缀合物比用九聚体接头合成的缀合物更具免疫原性。 轮状病毒是全球婴儿腹泻的最常见原因。两种获得许可的口服轮状病毒疫苗提供有限的保护，并且发现一些批次含有少量的猪圆环病毒1和2 DNA。我们正在设计一种基于衣壳蛋白的非肠道疫苗。在E.并在小鼠和豚鼠中引起中和抗体。重组蛋白与多糖疫苗的缀合改善了蛋白质溶解度。 还研究了衣壳蛋白的核心区域。 将在小鼠中比较核心蛋白与全长蛋白的免疫原性。 肠出血性大肠杆菌大肠杆菌（EHEC）感染是导致大肠杆菌病的主要原因。发达国家的大肠杆菌死亡人数。 在美国，流行的血清型是O 157 H：7。 肠出血性大肠杆菌菌株含有滋贺毒素（Stx）基因，释放的毒素可引起以下表现：从腹泻、出血性结肠炎到溶血性尿毒综合征（HUS）和血栓性血小板减少性紫癜。溶血尿毒综合征是幼儿急性和慢性肾损伤的主要原因，并可能导致死亡。 在美国2-5岁儿童的II期研究中，基于LPS的缀合物疫苗在98%的儿童中引起具有杀菌活性的抗体增加>10倍。 计划进行婴儿安全性和免疫原性研究。 大多数肠出血性大肠杆菌感染是由分泌Stx 2的菌株引起的。通过改进的重组技术，以高产量纯化了无毒的Stx 2 B亚基。 Stx 2B可作为E.大肠杆菌O 157 O-SP结合疫苗，以提供更广泛的覆盖面。

The capsular polysaccharide of Salmonella typhi (Vi) is a licensed vaccine but with limited efficacy in children less than 5 years old. To provide a vaccine for younger children, Vi was conjugated to recombinant exoprotein A of Pseudomonas aeruginosa (rEPA). An efficacy of 89% at 47 months was shown in 2-to-5-year olds injected with Vi-rEPA. Safety and immunogenicity of Vi-rEPA, administered concurrently with routine vaccines in the Expanded Program of Immunization (EPI) at 2, 4, 6 and 12 months were evaluated in 301 Vietnamese infants. Controls received Hib-TT +EPI or EPI alone. No serious adverse events occurred in any groups. The GM IgG anti-Vi level in the Vi-rEPA group was significantly higher than in the control groups; one month after the last injection 90% infants had higher than the estimated protective level. There was no difference in the level of IgG antibodies to the toxoids of diphtheria (DT), tetanus (TT) and to pertussis toxin among all groups; Vi-rEPA is suitable for routine immunization in infants. In collaboration with the International Vaccine Institute and Novartis Institute for Global Health, Vi was conjugated to licensed vaccines such as DT and TT. In mice, these conjugates elicited similar IgG anti-Vi levels to those induced by Vi-rEPA. Salmonella paratyphi A (SPA) is the second most common cause of enteric fever in developing countries, transmitted through ingestion of food or drink contaminated by infected persons. A chronic carrier was identified in an investigation of SPA outbreak by measuring serum anti-LPS levels among SPA infections (rectal swab positive individuals). In collaboration with the Guangxi Center for Disease Prevention and Control an expanded survey was initiated in a high endemic area to screen for potential chronic carriers. Vibrio cholerae O1 remains a major health problem in the Indian subcontinent and in Africa. Field studies showed that serum vibriocidal activity is directed toward its LPS. In a phase 1 trial, V. cholera O-SP conjugates elicited IgG anti-LPS with vibriocidal activity. A hexamer corresponding to the O-SP was chemically synthesized and conjugated to TT. In mice this conjugate elicited higher vibriocidal activities than the native O-SP conjugate used in the Phase I study. Various linker lengths were studied. A conjugate synthesized with a heptadecamer linker was more immunogenic than the one with a nonamer linker. Rotavirus is the most common cause of infantile diarrhea worldwide. Two licensed oral rotavirus vaccines confer limited protection and some lots were found to contain small amounts of porcine circovirus 1 and 2 DNA. We are designing a parenteral vaccine based on capsid proteins. Recombinant capsid proteins with truncated C or N termini were expressed in E. coli and elicited neutralizing antibodies in mice and guinea pigs. Conjugation of the recombinant proteins to polysaccharide vaccines improved protein solubility. The core region of the capsid protein was also investigated. Comparison of immunogenicity of the core with the full length protein will be conducted in mice. Enterohemorrahagic E. coli (EHEC) infections are the leading cause of E. coli deaths in developed countries. In the US, the prevalent serotype is O157H:7. EHEC strains contain the Shiga toxin (Stx) gene and the released toxin can cause the following manifestations; from diarrhea, hemorrhagic colitis, to hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura. HUS is a major cause of acute and chronic kidney damage in young children and could lead to death. In a phase II study in 2-5 years old children in the US, an LPS based conjugate vaccine elicited a >10 fold rise of antibodies with bactericidal activity in 98% the children. An infant safety and immunogenicity study is planned. Most EHEC infections are caused by strains secreting Stx2. The non-toxic B-subunit of Stx2 was purified in high yield by an improved recombinant technique. Stx2B could serve as a carrier protein for the E. coli O157 O-SP conjugate vaccine to provide a broader coverage.