MODULAR CHIMERIC VACCINES TAILORED FOR MALARIA PARASITES

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 疟疾寄生虫生命周期的复杂性和已达到临床开发第2阶段的候选疫苗报告的不良功效鼓励寻找替代方法以引起保护性免疫。我们已经设计并表达了几种红细胞前和红细胞嵌合重组蛋白，以寻找能够诱导长期抗疟疾保护的最佳制剂。在小鼠中使用啮齿动物疟疾寄生虫模型约氏疟原虫进行了原理验证研究。效力测试已经证实，嵌合蛋白是高度免疫原性的，并且能够诱导针对嵌合体的不同组分的稳健的免疫应答。最相关的是，疫苗构建体在用约氏疟原虫子孢子进行实验性攻击后以非常低的剂量对高寄生虫血症和严重贫血两者赋予保护。实验性攻毒后的潜伏期延迟和低寄生虫负荷表明，抗红细胞前免疫和抗血期免疫均起保护作用。为了评估抗体在保护中的影响，使用针对嵌合蛋白的两种主要组分引发的多克隆抗体进行被动免疫实验。这些比较实验证实，针对血液阶段组分的功能性抗体对于保护是必不可少的。我们还确定需要CD 4+而不是CD 8 + T细胞。这是第一个证据表明，多阶段蛋白质疫苗可以引发疟疾的保护性免疫。实验正在进行中，以设计一种嵌合疫苗，也纳入了性阶段疫苗的组成部分。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The complexity of the malaria parasite life cycle and the poor efficacy reported for vaccines candidates that have reached Phase 2 of clinical development has encouraged the search of alternative methodologies to elicit protective immunity. We have designed and expressed several pre-erythrocytic and erythrocytic chimeric recombinant proteins in the search of an optimal formulation capable of inducing long-term protection against malaria. Proof of principle studies have been done in mice using the rodent malaria parasite model Plasmodium yoelii. Potency tests have confirmed that the chimeric protein is highly immunogenic and able to induce robust immune responses against different components of the chimera. Most relevantly, the vaccine construct confers protection at very low doses to both hyper-parasitemia and severe anemia after experimental challenge with P. yoelii sporozoites. Delay in the prepatent period and low parasite burden after experimental challenge suggested that both, anti-pre-erythrocytic immunity and anti-blood stage immunity played a role in protection. To evaluate the impact of antibodies in protection, passive immunization experiments were done using polyclonal antibodies elicited against the two major components of the chimeric protein. These comparative experiments confirmed that functional antibodies against the blood stage component are essential for protection. We also established that CD4+ but not CD8+ T cells are required. This is the first evidence that a multi-stage protein-based vaccine can elicit protective immunity in malaria. Experiments are in progress to design a chimeric vaccine that also incorporates a sexual stage vaccine component.