Identifying functional antibody responses that protect against malaria in children

该项目旨在确定决定疟疾结果的抗体反应的目标和特征 非洲儿童感染。它使用系统血清学，结合多维抗体分析， 利用机器学习，研究对恶性疟原虫红细胞膜蛋白1（PfEMP 1）的反应， 疟疾感染红细胞（IE）表面的主要抗原。我们还研究了关键的裂殖子抗原， 其涉及对无症状寄生虫血症（AP）或单纯性疟疾（UM）的保护。 应答包括抗体亚类、同种型和Fc受体和补体接合，以及 抗体糖基化和亲合力。一些PfEMP 1类型与脑型疟疾（CM）有关;其他类型可能 影响范围包括AP、寄生虫清除和进展为UM的结果。我们 早期的工作验证了这种方法。我们将系统血清学应用于妊娠期疟疾， 确定对介导胎盘疟疾（VAR 2CSA）的PfEMP 1的七种关键反应， 易感染胎盘疟疾的妇女免受受保护妇女的影响。这七个中的四个是基于IE的测定。 这项研究计划是在马拉维的布兰太尔进行的，布兰太尔是一个国际疟疾研究中心 （ICEMR）网站。在正在进行的研究中，患有CM的儿童进行视网膜检查和MRI扫描，以评估神经血管 受累和脑肿胀。UM对照组和AP社区对照组是 注册并维持。在目标1中，我们将Luminex技术用于急性和恢复期血浆和寄生虫 分离物，以表征对广泛PfEMP 1蛋白片段的抗体应答，这些蛋白片段涉及严重 疟疾从这些分析中，我们将确定儿童缺乏的PfEMP 1结构域的抗体应答 与CM，有或没有视网膜病变和脑肿胀的儿童之间的差异， 从CM恢复。 在目标2中，使用基于细胞的吞噬作用测定深入研究了目标1中鉴定的优先PfEMP 1， PfEMP 1片段和表达类似PfEMP 1类型的寄生虫系的呼吸爆发和激活。 为此，我们已经建立了使用单核细胞、中性粒细胞、NK细胞和全血的测定法。 目标3使用马拉维ICEMR招募的社区队列，包括AP儿童，研究如何 PfEMP 1和裂殖子抗原的抗体影响AP的演变，以鉴定抗体应答 防止进展为UM或导致感染清除。这些全面、综合的研究将 比较和对比抗体反应，保护对CM，对UM，并清除寄生虫血症。 确定PfEMP 1抗体的靶点和特性，这些抗体与生命保护相关 威胁非洲儿童的疟疾将是开发定制疫苗或治疗方法的关键， 治疗严重的疟疾。在疟疾感染谱中发现关键的保护性抗体反应， 揭示PfEMP 1抗体和裂殖子对疟疾控制和消除的重要性。

This project aims to identify the targets and features of antibody responses that determine the outcome of malaria infection in young African children. It uses Systems Serology, combining multi-dimensional antibody profiling with machine learning, to study responses to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), the dominant antigen on the surface of malaria infected erythrocytes (IEs). We also study key merozoite antigens, which are implicated in protection from asymptomatic parasitemia (AP) or uncomplicated malaria (UM). Responses include antibody subclass, isotype, and Fc receptor and complement engagement, together with antibody glycosylation and avidity. Some PfEMP1 types are implicated in cerebral malaria (CM); others may influence outcomes across a spectrum which includes AP, clearance of parasites and progression to UM. Our earlier work validates this approach. We applied Systems Serology to pregnancy malaria and were able to identify seven key responses to the PfEMP1 that mediates placental malaria (VAR2CSA), that distinguished women susceptible to placental malaria from protected women. Four of these seven were IE based assays. The proposed study is based in Blantyre, Malawi, an International Center of Excellence in Malaria Research (ICEMR) site. In ongoing studies, children with CM have retinal exams and MRI scans to assess neurovascular involvement and brain swelling, respectively. Cohorts of controls with UM and community controls with AP are enrolled and sustained. In Aim 1, we use Luminex technology on acute and convalescent plasma and parasite isolates to characterize antibody response to a broad range of PfEMP1 protein fragments implicated in severe malaria. From these analyses we will identify antibody responses to PfEMP1 domains that are lacking in children with CM, that differ between children with or without retinopathy and brain swelling, and that develop in convalescence from CM. In Aim 2, priority PfEMP1s identified in Aim 1 are studied in depth using cell-based assays of phagocytosis, respiratory burst and activation with both PfEMP1 fragments and parasite lines expressing similar PfEMP1 types. We have established assays using monocytes, neutrophils, NK cells and whole blood for this purpose. Aim 3 uses community cohorts recruited by the Malawi ICEMR, including children with AP, to study how antibodies to PfEMP1 and to merozoite antigens influence the evolution of AP, to identify antibody responses that prevent progression to UM or lead to clearance of infection. These comprehensive, integrated studies will compare and contrast antibody responses that protect against CM, against UM, and that clear parasitemia. Identifying the targets and properties of antibodies to PfEMP1 that are associated with protection from life threatening malaria in African children will be key to developing tailored vaccines or therapeutics to prevent or treat severe malaria. Discovering key protective antibody responses across the malaria infection spectrum will reveal the importance of antibody to PfEMP1 and merozoites for malaria control and elimination.