Duffy antigen presentation and its correlation to parasite invasion

描述（由申请人提供）：据估计，世界上有32亿人面临疟疾风险，而疫苗开发工作尚未成功。疟疾物种间日疟原虫和诺氏疟原虫共造成7000万至8000万人感染疟疾，是有效疟疾疫苗的关键目标物种。此外，间日疟原虫感染会导致以前未接触过寄生虫的患者出现衰弱症状。驻扎在阿富汗和伊拉克等间日疟原虫流行地区的美国武装部队对疾病的这一特征特别感兴趣。与之密切相关的诺氏疟原虫是一种新出现的病原体，在东南亚一些地区占所有疟疾感染的20%。据观察，只有在红细胞表面表达达菲血型抗原的人才会感染血液阶段的诺氏疟原虫或间日疟原虫。目前的几种疫苗策略集中在中断达菲抗原和寄生虫达菲结合蛋白（DBP）的相互作用。虽然这种策略是有希望的，但对达菲受体的表达以及这种疫苗策略是否有效知之甚少。以前的研究表明，达菲抗原的表达可能会有所不同，在达菲阳性人群。在本提案中，我们将讨论以下问题：a）达菲阳性个体的表型（Fya+/Fya+、Fya+/Fy B+和Fy B+、Fy B+）在Duffy受体的分布或对DBP的结合亲和力方面不同，B）供体的性别是否影响DBP的结合，c）红细胞表面拓扑结构是否影响DBP的结合，和d）更大的DBP结合亲和力是否导致寄生虫感染水平的增加？为了解决这些问题，我们将确定红细胞表面上的达菲受体表达的水平和位置，确定重组DBP变体的结合亲和力，并使用高通量流式细胞术测量寄生虫侵袭效率。我们将在三个样本分组中研究这些参数;表达Fya、Fyb或Fya/Fyb Duffy受体的男性，Fya或Fyb纯合阳性的男性和女性，以确定供体的性别是否影响Duffy受体分布，以及：血红蛋白或红细胞表面蛋白变体患者的样本。我们相信，这些研究将产生重要的信息，寄生虫入侵，这将指导疫苗的开发和实施。相关性（参见说明）：这项研究的相关性在于它有助于了解疟疾寄生虫如何侵入红细胞以及人类如何改变以避免这种感染。基于这些知识，我们可以设计出一种有效的疫苗来对抗5种疟疾中的2种。我们设计的疫苗将于2011年开始在巴布亚新几内亚进行测试。

DESCRIPTION (provided by applicant): An estimated 3.2 billion people in the world are at risk for malaria while vaccine development efforts have yet to be successful. The malaria species Plasmodium vivax and Plasmodium knowlesi together account for 70-80 million human malaria infections and represent the key target species for an effective malaria vaccine. Additionally, P. vivax infection causes debilitating symptoms in patients who have previously been unexposed to the parasite. This characteristic of the disease is of particular interest to the U.S. Armed Forces who are stationed in P. vivax endemic areas such as Afghanistan and Iraq. The closely related species P. knowlesi, a newly emerging pathogen, accounts for up to 20% of all malaria infections in some regions of Southeast Asia. It has been observed that only people that express the Duffy blood group antigen on the surface of their erythrocytes become infected with blood-stage P. knowlesi or P. vivax. Several current vaccine strategies are focused on interruption of the interaction of the Duffy antigen and the parasite Duffy binding protein (DBP). While this strategy is promising, little is known about the expression of the Duffy receptor and whether such a vaccine strategy would be effective. Previous studies have suggested that Duffy antigen expression may vary across Duffy positive populations. In this proposal we will address the following questions: a) do phenotypes of Duffy positive individuals (Fya+/Fya+, Fya+/Fyb+, and Fyb+,Fyb+) differ in the distribution of Duffy receptors or binding affinity to DBP, b) does the sex of the donor influence the binding of DBP, c) does erythrocyte surface topology influence DBP binding, and d) does greater DBP binding affinity lead to increased levels of parasite infections? To address these questions we will identify the level and location of Duffy receptor expression on the surface of erythrocytes, determine binding affinity of recombinant DBP variants, and measure parasite invasion efficiency using high throughput flow cytometry. We will study these parameters across three sample groupings; males expressing Fya, Fyb, or Fya/Fyb Duffy receptors, males and females homozygous positive for Fya or Fyb to identify if the sex of the donor effects Duffy receptor distribution, and: samples from patients with hemoglobin or erythrocyte surface proteins variants. We believe that these studies will yield important information about parasites invasion which will guide vaccine development and implementation. RELEVANCE (See instructions): The relevance of this study is that it helps understand how malaria parasites invade red blood cells and how humans have changed to avoid this infection. Based on this knowledge we can design an effective vaccine against 2 of the 5 types of malaria. The vaccine we design will be tested in Papua New Guinea starting in 2011.