Molecular Determinants of Sporozoite / Host Cell Interactions

项目总结/摘要 由疟原虫寄生虫引起的疟疾仍然是一个主要的全球健康问题， 每年有100万新感染者和近50万人死亡。感染开始时，孢子阶段是 通过蚊子载体接种到皮肤中。然后子孢子在皮肤组织中移动，进入血液 流并到达肝脏。子孢子在最终感染肝细胞之前穿过细胞， 复制允许寄生泡（PV）。在PV膜（PVM）中， 子孢子将变形到复制的肝脏阶段，然后形成数万个裂殖子。 这些病毒从肝脏中释放出来，感染血细胞并在血细胞中复制，从而导致所有的临床症状。 疟疾，并使寄生虫进一步传播。因此，靶向红细胞前子孢子代表 这是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， 关键的分子相互作用导致子孢子进入宿主，感染肝脏， 和肝细胞的侵袭。在本提案中，我们将使用新的方法重点阐明 涉及含有P52、P36和TRAP的子孢子蛋白复合物的感染的分子图 复合物，以及它们分别与宿主受体EphA 2、CD 81和PDGFR β的相互作用。目前我们 我只知道P36和P52对于建立PVM的生产性肝细胞感染是必需的， 肝细胞表面受体EphA 2和CD 81对于PVM的形成也是关键的。在目标1中，我们 研究在相互作用期间子孢子释放P52和P36的动力学和条件， 肝细胞在我们初步分离出P52/P36复合物后，我们将继续确定 该复合物内的精确分子相互作用及其与EphA 2、CD 81和任何其它新的 鉴定的推定受体。在目的2中，我们将重点放在肝细胞表面，以进一步研究功能 EphA 2在肝细胞侵袭和PV形成中意义及其与CD 81和 新型受体在目标3中，我们将研究一种新的寄生虫-宿主相互作用对， 宿主蛋白PDGFR β和子孢子粘附素TRAP的相互作用，以及这种相互作用对宿主的重要性 感染的背景下，一个大的陷阱，含有子孢子蛋白复合物，我们最近发现。 在完成拟议的工作后，我们将有一个明确的分子图的相互作用的关键 子孢子侵入相关蛋白复合物和宿主受体复合物。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， 有助于实现预防疟疾感染的目标。

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.