Molecular Determinants of Sporozoite / Host Cell Interactions

项目摘要/摘要 由疟原虫引起的疟疾仍然是一个主要的全球健康问题，有200多个 每年新增感染者100万人，死亡近50万人。感染开始于子孢子阶段 通过蚊子媒介接种到皮肤中。然后，子孢子在皮肤组织中移动，进入血液 流到肝脏。子孢子穿过细胞，最终感染体内的肝细胞 允许复制的寄生性空泡(PV)。安放在光伏膜(PVM)中，单个 子孢子将变形到肝脏阶段，然后复制并形成数万个裂殖子。 它们从肝脏释放，感染并在血细胞中复制，从而导致所有临床症状 疟疾，并使寄生虫进一步传播。因此，以前红细胞子孢子为靶标代表 一个有吸引力的干预点，因为它们的数量很少，并且成功地破坏了分子 感染所需的相互作用将完全防止疾病和传播。然而，人们对此知之甚少 关于导致产子孢子进入宿主、肝脏感染的关键分子相互作用 和肝细胞的侵袭。在这项提案中，我们将使用新的方法，重点阐明 包含P52、P36的子孢子蛋白复合体和陷阱的感染分子图谱 以及它们分别与宿主受体EphA2、CD81和PDGFR的相互作用。目前我们 只知道P36和P52对于建立生产性肝细胞感染PVM是必不可少的，并且 肝细胞表面受体EphA2和CD81也是PVM形成的关键。在目标1中，我们将 研究P52和P36在与子孢子相互作用过程中释放的动力学和条件 肝细胞。在我们初步分离出P52/P36复合体后，我们将继续确定 该复合体内的精确分子相互作用及其与EphA2、CD81和任何其他新的分子相互作用 鉴定了可能的受体(S)。在目标2中，我们将重点放在肝细胞表面，以进一步研究功能 EphA2在肝细胞侵袭和PV形成中的意义及其与CD81和CD81的关系 新的感受器。在目标3中，我们将研究我们发现的一种新的寄生虫-宿主相互作用对 宿主蛋白PDGFR和子孢子粘附素陷阱以及这种相互作用对宿主的重要性 感染与我们最近发现的含有大量TRAP的子孢子蛋白复合体有关。 在拟议的工作完成后，我们将有一个关于关键分子相互作用的清晰的分子图谱 子孢子入侵相关蛋白复合体和宿主受体复合体。这些数据将对 设计有针对性的干预措施，如感染阻断抗体或小分子抑制剂，并因此 为预防疟疾感染的目标作出贡献。

PROJECT SUMMARY/ABSTRACT Malaria, caused by Plasmodium parasites, continues to be a major global health problem, with more than 200 million new infections and nearly 500 thousand deaths annually. Infection initiates when sporozoite stages are inoculated into the skin by the mosquito vector. Sporozoites then move in the skin tissue, enter the blood stream and reach the liver. Sporozoites traverse cells before eventually infecting a hepatocyte within a replication-permissive parasitophorous vacuole (PV). Ensconced in the PV membrane (PVM), a single sporozoite will transmogrify into a liver stage that replicates and then forms tens of thousands of merozoites. These are released from the liver and infect and replicate in blood cells, which causes all clinical symptoms of malaria and enables further parasite transmission. Targeting the pre-erythrocytic sporozoites thus represents an attractive intervention point since they are small in number, and successful disruption of the molecular interactions required for infection would completely prevent disease and transmission. However, little is known about the critical molecular interactions leading to productive sporozoite entry into the host, infection of the liver and invasion of hepatocytes. In this proposal, using novel approaches, we will focus on elucidating the molecular map of infection that involves the sporozoite protein complexes containing P52, P36 and the TRAP complex, and their interactions with the host receptors EphA2, CD81 and PDGFR, respectively. Currently we only know that P36 and P52 are essential for establishing productive hepatocyte infection with a PVM and that the hepatocyte surface receptors EphA2 and CD81 are critical for PVM formation as well. In Aim 1, we will investigate the dynamics and conditions of release of P52 and P36 from sporozoites during interaction with hepatocytes. Following our preliminary isolation of a P52/P36 complex, we will proceed to determine the precise molecular interactions within this complex and its interaction with EphA2, CD81 and any other novel putative receptor(s) identified. In Aim 2, we will focus on the hepatocyte surface to further study the functional significance of EphA2 during hepatocyte invasion and PV formation as well as its relationship to CD81 and novel receptors. In Aim 3, we will investigate a novel parasite-host interaction pair identified by us between host protein PDGFR and the sporozoite adhesin TRAP, and the importance of this interaction for host infection in the context of a large TRAP-containing sporozoite protein complex that we have recently identified. Upon completion of the proposed work we will have a clear molecular map of the interactions of critical sporozoite invasion-related protein complexes and host receptor complexes. This data will be important to design targeted interventions such as infection-blocking antibodies or small molecule inhibitors and as such will contribute to the goal of preventing malaria infection.