Antibody biomarker discovery for current and recent asymptomatic malaria exposure

项目摘要/摘要 迫切需要敏感的、可现场部署的疟疾监测工具，以指导 在消除区部署干预措施，那里的传播是集中的，疟疾风险是不同的。 超灵敏的分子方法显示，在这些环境中，大多数疟疾感染是亚临床的， 低密度感染，标准诊断测试无法检测到的感染，充当了静默的蓄水池 疟疾传播。然而，超灵敏的分子方法昂贵、耗时，需要良好的- 配备了实验室，因此无法提供接触点结果，限制了它们在远程疟疾中的应用- 地方病流行地区。理想的监测工具不仅可以测量寄生虫的流行情况，还可以估计最近 疟疾暴露情况，提供了人口中疟疾的更有力的特征。抗体生物标志物有 在这一环境中有希望成为疟疾监测的目标，因为它们可以表明累积接触情况，并且 轻松集成到现有的护理点平台中。然而，血清标志物仍未得到充分利用，原因是 在如何解释结果方面缺乏明确的目标或共识。许多血清反应性最强的疟疾 抗原也是最多态的，基于对参考菌株蛋白的反应而产生的混杂结果。 这项工作建议利用这种多样性来识别信息丰富的抗体生物标记物来估计疟疾 曝光。根据我们的初步数据，这项提议的中心假设是，接触 低密度疟疾感染具有独特的血清学特征，可用于快速评估最近的 以及目前的曝光量。这一假设将通过以下具体目标进行检验：1)识别抗体 当前和最近(6个月)亚临床恶性疟原虫和间日疟原虫的生物标志物 暴露，以及2)使用基于多重珠基的多路传输验证针对疟疾抗原的新的多肽靶点 免疫分析格式。在目标1中，将通过测量匹配的血清反应性来识别抗体生物标记物。 在新的超高密度多肽阵列上暴露和未暴露的个体，这些序列来自 恶性疟原虫和间日疟原虫两个参考菌株的抗原变体，在地理上- 相关的字段隔离。在目标2中，向下选择的多肽将被批量合成并结合到条形码 用于多重荧光免疫分析的磁珠。多肽靶标的血清反应性将是 根据已知疟疾暴露者和地方病流行者的特征良好的样本进行测量 控制。这项拟议的工作是朝着开发一种强大的接触点测试迈出的第一步，该测试可用于 确定疟疾传播和风险的特征，最终能够更好和更准确地确定干预措施的目标。

PROJECT SUMMARY/ABSTRACT There is a pressing need for sensitive, field-deployable malaria surveillance tools to guide the optimal deployment of interventions in elimination zones, where transmission is focal and malaria risk heterogeneous. Ultrasensitive molecular methods have revealed that most malaria infections in these settings are subclinical, low-density infections, which are not detectable by standard diagnostic tests, serving as a silent reservoir for malaria transmission. However, ultrasensitive molecular methods are expensive, time-consuming, require a well- equipped laboratory, and thus cannot provide point-of-contact results, limiting their utility in remote malaria- endemic areas. An ideal surveillance tool would not only measure parasite prevalence, but also estimate recent malaria exposure, providing a more robust characterization of malaria in a population. Antibody biomarkers are promising targets for malaria surveillance in this setting because they can indicate cumulative exposure and are easily integrated into existing point-of-care platforms. However, serological markers remain underutilized due to a lack of well-defined targets or consensus on how to interpret results. Many of the most seroreactive malaria antigens are also the most polymorphic, confounding results based on reactivity to reference-strain proteins. This work proposes to leverage this diversity to identify informative antibody biomarkers to estimate malaria exposure. Based on our preliminary data, the central hypothesis of this proposal is that individuals exposed to low-density malaria infections have unique serological profiles that can be used for rapid evaluation of recent and current exposure. This hypothesis will be tested with the following specific aims: 1) Identify antibody biomarkers for current and recent (6 months) subclinical Plasmodium falciparum and Plasmodium vivax exposure, and 2) validate novel peptide targets against malaria antigens using a multiplexed bead-based immunoassay format. In Aim 1, antibody biomarkers will be identified by measuring seroreactivity of matched exposed and unexposed individuals on novel ultra-dense peptide arrays populated with sequences from Plasmodium falciparum and Plasmodium vivax antigen variants from both reference strains and geographically- relevant field isolates. In Aim 2, down-selected peptides will be synthesized in bulk and conjugated to barcoded magnetic beads for a multiplexed fluorescence-based immunoassay. Seroreactivity to peptide targets will be measured on well-characterized samples from individuals with known malaria exposure as well as endemic controls. The proposed work is the first step toward developing a robust point-of-contact test that can be used to characterize malaria transmission and risk, ultimately enabling better and more precise targeting of interventions.