Leptospirosis Vaccine Development

摘要/摘要。钩端螺旋体病是由致病性钩端螺旋体引起的一种全球重要的被忽视的疾病。 据估计，它每年造成100多万例全球病例，病死率为5%-20%，显著 发病率和重要的公共卫生后果。目前还没有安全有效的疫苗来预防 预防人类钩端螺旋体病。LeptoX，Inc.计划开发第一种人类钩端螺旋体病疫苗。 致病性钩端螺旋体是胞外生物，但它们发挥致病作用的机制 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，其效果尚不清楚。 接下来，我们展示了Vm蛋白作为PAN抗原成分的可能性- 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 L.审讯官。这项提案的重点是问号钩端螺旋体VM蛋白疫苗，尽管 跨物种保护可能是可能的。最近公布的动物模型数据表明，只有 两个重组的Vm蛋白提供了强大的跨血清保护，防止致死性L. 审讯者在老鼠身上挑战。这些数据表明，Vm蛋白作为PAN-L具有很强的潜力。被审讯者 保护性抗原。在这一阶段，我们将优化重组大肠杆菌的剂量、递送和组成。 生产的VM蛋白与人类相容的佐剂相结合，以确定对 致死性仓鼠钩端螺旋体病攻击模型。在目标1中，我们将生产重组无标签Vm蛋白 免疫原，分析它们的免疫原性，并在标准仓鼠模型中比较它们的保护作用 对标准的商业化疫苗的有效性；应急试验也将评估 化学灭活的野生型蛋白和从包涵体中纯化的蛋白作为 Vm蛋白免疫原；结构模拟表明Vm蛋白二硫键依赖的构象 可能不是抗原性的关键。在目标2中，我们将比较野生型和基因突变的类毒素形式 在致死仓鼠模型中，无标签、重组大肠杆菌产生的Vm蛋白。 保护性免疫反应 因为这两个目标都将通过预防临床疾病和死亡以及通过细菌检测来评估 不同时间点的肝脏和肾脏的负荷和活力。保护性免疫的生物标志物(即抗体 针对原型疫苗抗原的效价和不同血清型之间以及不同血清型之间的交叉反应 将测定钩端螺旋体物种的Vm蛋白)；推测抗体介导的保护机制 免疫力将通过被动转移实验进行测试。在这个第一阶段项目结束时，我们将拥有 开发了最终的PAN-L。询问以VM蛋白为基础的疫苗原型，以进行进一步的动物试验。跟随 第一阶段，这个原型将在狗的临床试验中进行测试，这将导致这些产品的第一个商业化产品 同伴动物。动物疫苗的开发将导致FDA向人类提交IND 钩端螺旋体病疫苗，将在此基础上形成钩端螺旋体病疫苗开发的战略伙伴关系。

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.