Leptospirosis Vaccine Development

摘要/Abstract钩端螺旋体病是由致病性钩端螺旋体引起的一种全球性的重要疾病。 据估计，全球每年有超过100万例病例，病死率为5 - 20%， 发病率和严重的公共卫生后果。目前还没有安全有效的疫苗 预防人类钩端螺旋体病。LeptoX，Inc.建议研制首个人类钩端螺旋体病疫苗。 致病性钩端螺旋体是细胞外生物，但它们发挥致病性的机制 在我们发现钩端螺旋体毒力修饰（VM）蛋白的细胞毒素功能之前， 其次，我们证明了VM蛋白作为泛- 钩端螺旋体病疫苗。据报道，严重的人类钩端螺旋体病几乎完全是由于 L.质问者该建议侧重于L。问号VM蛋白为基础的钩端螺旋体病疫苗，虽然 跨物种保护是可能的。最近发表的动物模型数据表明， 两种重组VM蛋白在致死性L. 小鼠中的问号激发。这些数据表明VM蛋白作为pan-L的强大潜力。问号 保护性抗原在第一阶段，我们将优化重组大肠杆菌的剂量、递送和组成。大肠杆菌 产生的VM蛋白与人相容性佐剂组合，以确定在 钩端螺旋体病致死仓鼠攻击模型。目的1：构建重组无标签VM蛋白 免疫原，分析其免疫原性，并在标准仓鼠模型中，比较其保护性 有效性标准，市售疫苗;应急实验也将评估 化学失活的野生型蛋白和从包涵体纯化的蛋白， VM蛋白免疫原;结构建模表明VM蛋白二硫键依赖性构象 对于抗原性可能不是关键的。在目标2中，我们将比较野生型和基因突变的类毒素形式 无标签重组E.大肠杆菌产生的VM蛋白在致死仓鼠模型。 保护性免疫应答 对于这两个目的，将通过对临床疾病和死亡的保护以及通过测定细菌 在不同时间点的肝脏和肾脏中的负荷和活力。保护性免疫的生物标志物（即，抗体 针对原型疫苗抗原的滴度以及血清型之间和不同血清型之间的交叉反应性 将测量钩端螺旋体物种的VM蛋白）; 免疫力将通过被动转移实验进行测试。在第一阶段项目结束时，我们将拥有 最终形成了泛L。基于问号病毒VM蛋白的疫苗原型用于进一步的动物试验。以下 在第一阶段，这个原型将在狗的临床试验中进行测试，这将导致第一个商业产品， 伴侣动物动物疫苗的开发将导致FDA向人类提交IND 在此基础上，将建立开发钩端螺旋体病疫苗的战略伙伴关系。

Summary/abstract. Leptospirosis is a globally important neglected disease caused by pathogenic Leptospira. It is estimated to cause more than 1 million global cases annually with a 5-20% case-fatality rate, significant morbidity, and important public health consequences. Currently there is no safe and effective vaccine to prevent human leptospirosis. LeptoX, Inc. proposes to develop the first human leptospirosis vaccine. Pathogenic Leptospira are extracellular organisms, but mechanisms by which they exert their pathogenetic effects were unclear until our discovery of the leptospiral Virulence Modifying (VM) proteins’ cytotoxin function, followed by our demonstration of the potential for VM proteins to be the antigen components of a pan- leptospirosis vaccine. Severe human leptospirosis has almost exclusively been reported to be due to strains of L. interrogans. This proposal focuses on a L. interrogans VM protein-based leptospirosis vaccine, although cross species protection may be possible. Recently published animal model data demonstrated that as few as two recombinant VM proteins provide robust cross-serovar protection from disease/death after lethal L. interrogans challenge in mice. These data indicate strong potential for VM proteins as pan-L. interrogans protective antigens. In this Phase I, we will optimize dose, delivery and composition of recombinant E. coli- produced VM proteins in combination with human-compatible adjuvant to determine protective efficacy in the lethal hamster challenge model of leptospirosis. In Aim 1, we will produce recombinant tagless VM protein immunogens, analyze their immunogenicity and, in the standard hamster model, compare their protective efficacy to standard, commercially available bacterin vaccines; contingency experiments will also assess chemically inactivated wild type proteins and proteins purified from inclusion bodies as alternative forms of the VM protein immunogen; structural modeling suggests that VM protein disulfide bond-dependent conformation may not be critical for antigenicity. In Aim 2, we will compare wild type and genetically mutated toxoid-forms of tagless, recombinant E. coli-produced VM proteins in the lethal hamster model. Protective immune responses for both Aims will be assessed by protection from clinical disease and death and by determination of bacterial load and viability in liver and kidney at various time points. Biomarkers of protective immunity (i.e., antibody titers against the prototype vaccine antigens and cross-reactivity among serovars and between different Leptospira species’ VM proteins) will be measured; the putative antibody-mediated protective mechanism of immunity will be tested by passive transfer experiments. At the end of this Phase I project, we will have developed final pan-L. interrogans VM-protein-based vaccine prototypes for further animal testing. Following Phase I, this prototype will be tested in dog clinical trials, which will lead to a first commercial product for these companion animals. Animal vaccine development will lead towards FDA IND submission for a human leptospirosis vaccine, upon which strategic partnerships for leptospirosis vaccine development will be formed.