The Skin Phase of Malaria Infection

项目摘要 疟疾仍然是世界上最重要的传染病之一。一种完全有效的疫苗将是 给我们的医疗设备增加了一大笔钱迄今为止最有希望的候选疫苗RTS，S，一种亚单位疫苗 由子孢子的主要表面蛋白CSP的一部分组成，已经显示出有限的功效， 在第一年之后，明显。虽然这福尔斯短社区建立的目标，RTS，S提供了一个 在此基础上我们可以制造出更有效的疫苗。本提案中概述的研究 目的是阐明寄主和寄生虫在接种部位的相互作用， 未来的疫苗设计子孢子被接种到哺乳动物宿主的皮肤中， 血很少有子孢子被注入，这使其成为寄生虫的瓶颈。在他们接种疫苗后， 子孢子在皮肤中活动，必须找到并穿透血管进入循环。 我们的研究表明，大多数子孢子需要20至120分钟才能离开真皮， 小部分成功进入血液循环。一旦进入血液循环，子孢子就会进入肝脏 并在几分钟内进入肝细胞子孢子通过真皮是一个研究不足的阶段， 疟疾感染：然而，接种子孢子的数量很少， 寄生虫是细胞外的最长一段时间在皮肤上，表明这是一个极端的时间 易损性.我的实验室已经研究子孢子传播的动力学好几年了， 我们现在正在使用定量活体成像，以更好地了解成功退出的要求， 真皮在目标1中，我们将对人类疟原虫进行活体成像研究 恶性疟原虫，定量分析其运动和血管相互作用，在小鼠皮肤和人体 异种皮肤移植与啮齿类疟疾子孢子的比较分析将确定保守的和物种- 皮肤退出的特定方面，并定义预测成功退出真皮的度量。这些研究将 还使得能够开发体内平台以筛选具有恶性疟原虫子孢子的疫苗候选物。 先前在小鼠和RTS，S免疫的人中的研究表明，CSP特异性抗体与免疫相关。 然而，在有保护的情况下，这些抗体影响子孢子的位置和机制并不清楚。 知道的在目标2和3中，我们将对啮齿动物和人类进行活体成像和感染研究。 疟疾子孢子，以确定：a）靶向两种主要子孢子疫苗候选物的抗体 在皮肤中具有最大的影响; B）功能性抗体依赖于其 抑制子孢子运动性相对于它们调理子孢子并通过先天性 c）快速滑行和细胞穿越是否能够使子孢子，至少在某些情况下， 逃避先天宿主反应和抗体的抑制活性。我们相信， 从这些研究中获得的信息将为未来疟疾候选疫苗的设计提供信息。

Project Summary Malaria remains one of the most important infectious diseases in the world. A fully effective vaccine would be a huge addition to our armamentarium. The most promising vaccine candidate to date, RTS,S, a subunit vaccine composed of a portion of the sporozoite's major surface protein, CSP, has shown limited efficacy that wanes significantly after the first year. Though this falls short of community established goals, RTS,S provides a substrate upon which we can build to create a more efficacious vaccine. The studies outlined in this proposal aim to elucidate the interactions between host and parasite at the inoculation site with the goal of improving future vaccine design. Sporozoites are inoculated into the skin of the mammalian host as mosquitoes search for blood. Few sporozoites are injected, making this a bottleneck for the parasite. After their inoculation, sporozoites are actively motile in the skin, and must find and penetrate blood vessels to enter the circulation. Our studies demonstrate that the majority of sporozoites take 20 to 120 minutes to exit the dermis and only a small proportion succeed in entering the blood circulation. Once in the circulation, sporozoites go to the liver and enter hepatocytes within minutes. Sporozoite passage through the dermis is an understudied phase of malaria infection: Yet, the low numbers of inoculated sporozoites together with the discovery that the parasite is extracellular for the longest period of time in the skin, suggest that this is a time of extreme vulnerability. My laboratory has been studying the dynamics of sporozoite transmission for several years and we are now using quantitative intravital imaging to better understand the requirements for successful exit from the dermis. In Aim 1, we will perform intravital imaging studies with the human malaria parasite Plasmodium falciparum, quantitatively analyzing its motility and blood vessel interactions, in both mouse skin and human skin xenografts. Comparative analysis with rodent malaria sporozoites will identify conserved and species- specific aspects of dermal exit and define metrics that predict successful exit from the dermis. These studies will also enable the development of an in vivo platform to screen vaccine candidates with P. falciparum sporozoites. Previous studies in mice and in RTS,S immunized humans have shown that CSP-specific antibodies correlate with protection, however, the location and mechanism(s) by which these antibodies impact sporozoites are not known. In Aims 2 and 3, we will perform intravital imaging and infection studies with rodent and human malaria sporozoites to determine: a) whether antibodies targeting the two leading sporozoite vaccine candidates have their its greatest impact in the skin; b) the degree to which functional antibodies rely on their ability to inhibit sporozoite motility versus their ability to opsonize sporozoites and direct their destruction by innate immune cells and c) whether fast gliding and cell traversal enable the sporozoite, at least in some cases, to escape the innate host response and the inhibitory activity of antibody. We feel confident that the knowledge gained from these studies will inform the design of future malaria vaccine candidates.