Imaging preerythrocytic Plasmodium stages in naive and immune individuals

本申请的广泛、长期目标是提供对受保护的个体和动物控制肝脏中疟原虫发育的基本细胞免疫机制的更好理解。尽管疟疾对数百万人造成严重影响，但对这种寄生虫在肝脏（哺乳动物宿主中复制的初始位点）中的基本免疫生物学仍然知之甚少。 疟疾特异性效应T细胞成功靶向寄生虫并将其从肝脏中消除的能力已经使用减毒疟疾子孢子疫苗模型充分建立。这种全生物体方法代表了疟疾疫苗的“黄金标准”，因为通过静脉注射或感染疟疾的蚊子叮咬给啮齿动物、猴子和人类接种放射性减毒子孢子，可以预防血液感染。了解哪种细胞毒性机制提供最高水平的保护可能有助于改进疫苗接种策略，以诱导这种反应，并提高发现更实用疫苗的机会，例如，多价亚单位疫苗提供了许多优点，包括更大的安全性，因为最大限度地减少了对非保护性决定因素的有害反应，降低了生产成本，易于储存。理想的情况是，这种疫苗可以预防全球200万至300万疟疾死亡，其中估计90%发生在非洲的幼儿中。 具体目的是利用显微成像的最新进展，以确定如何疟原虫肝脏阶段的发展和裂殖子释放可以中断免疫宿主。新的成像技术和仪器，转基因寄生虫和小鼠，高度特异性的荧光报告底物和分子探针将被用来阐明，肝细胞能够提出疟疾抗原的效应T细胞和细胞效应机制消除寄生虫从肝脏。靶细胞杀伤的直接可视化和分子分析，T细胞免疫的顶峰，将大大促进我们对疟疾肝脏阶段的适应性细胞介导的免疫反应的理解。

The broad, long-term objective of this application is to provide a better understanding of the basic cellular immune mechanisms by which protected individuals and animals control Plasmodium development in the liver. Despite the severe impact of malaria on millions of people, the basic immunobiology of this parasite in the liver, the initial site of replication in the mammalian host, is still poorly understood. The ability of malaria-specific effector T cells to successfully target the parasites and eliminate them from the liver has been well established using the attenuated malaria sporozoite vaccine model. This whole organism approach represents the "gold standard" for a malaria vaccine, since immunization of rodents, monkeys and humans with radiation-attenuated sporozoites, delivered by intravenous injection or the bite of malaria-infected mosquitoes, was shown to prevent blood infection. Understanding which of the possible cellular mechanisms of cytotoxicity provides the highest level of protection may help refine vaccination strategies to induce such responses and improve the chance that more practical vaccines can be found. For example, multivalent subunit vaccines offer numerous advantages including greater safety due to minimized deleterious responses against non-protective determinants, lower production costs, and ease of storage. Ideally, such a vaccine would prevent the 2-3 million malaria deaths worldwide, an estimated 90% of which occur in young children in Africa. The Specific Aim is to exploit the recent advances in microscopic imaging to determine how Plasmodium liver stage development and merozoite release can be interrupted in an immune host. Novel imaging techniques and instrumentation, transgenic parasites and mice, highly specific fluorogenic reporter substrates and molecular probes will be used to elucidate, which liver cells are able to present malaria antigen to effector T cells and which cellular effector mechanisms eliminate the parasites from the liver. Direct visualization and molecular analysis of target cell killing, the pinnacle of T cell immunity, will greatly advance our understanding of the adaptive cell-mediated immune response against malaria liver stages.