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应该是 为我们的武器库增添了巨大的力量。迄今为止最有希望的候选疫苗，RTS，S，亚单位疫苗 由子孢子的主要表面蛋白CSP的一部分组成，显示出有限的疗效，但逐渐减弱 在第一年之后显著增加。尽管这没有达到社区确立的目标，但S提供了一个 我们可以在它的基础上制造出更有效的疫苗。这项提案中概述的研究 目的阐明接种现场宿主和寄生虫之间的相互作用，以期提高接种效果。 未来的疫苗设计。子孢子被接种到哺乳动物宿主的皮肤中，以供蚊子寻找 血。注射的子孢子很少，这使这成为寄生虫的瓶颈。在他们接种后， 子孢子在皮肤中活动活跃，必须找到并穿透血管才能进入循环。 我们的研究表明，大多数子孢子需要20到120分钟才能离开真皮，只有 成功进入血液循环的比例较小。一旦进入循环，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未被充分研究的阶段 疟疾感染：然而，接种的子孢子数量很少，同时发现 寄生虫在皮肤细胞外停留的时间最长，这表明这是一个极端的时期 脆弱性。我的实验室几年来一直在研究子孢子传播的动力学 我们现在正在使用定量的生命内成像来更好地了解成功退出的要求 真皮。在目标1中，我们将对人类疟疾寄生虫疟疾进行活体成像研究。 恶性疟原虫，定量分析其在小鼠皮肤和人皮肤中的运动和血管相互作用 异种皮肤移植。与啮齿动物疟疾子孢子的比较分析将确定保守的和物种- 真皮退出的特定方面，并定义预测成功退出真皮的指标。这些研究将 还支持开发体内平台，以筛选带有恶性疟原虫子孢子的候选疫苗。 先前在小鼠和RTS中的研究表明，S免疫的人类CSP特异性抗体与 然而，有了保护，这些抗体影响子孢子的位置和机制(S)就不再是 为人所知。在目标2和目标3中，我们将对啮齿动物和人类进行活体成像和感染研究。 疟疾子孢子确定：a)针对两个主要子孢子疫苗候选者的抗体 对皮肤有最大的影响；b)功能性抗体依赖于其能力的程度 抑制子孢子的运动与其调理子孢子并引导先天销毁子孢子的能力 C)快速滑动和细胞遍历是否至少在某些情况下使子孢子能够 逃避天然的宿主反应和抗体的抑制活性。我们对这些知识充满信心 从这些研究中获得的信息将为未来疟疾疫苗候选疫苗的设计提供依据。

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.