Antibody biomarker discovery for current and recent asymptomatic malaria exposure

当前和近期无症状疟疾暴露的抗体生物标志物发现

• 批准号: 10369588
• 负责人: Christine Markwalter
• 金额: $ 7.23万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10369588
• 关键词: Antibodies; Antibody Response; Antigens; Area; Bangladesh; Bar Codes; Biological Assay; Biological Markers; Blood; China; Collection; Consensus; Consumption; Custom; Data; Diagnostic; Diagnostic tests; Epitopes; Evaluation; Exposure to; Fluorescence; Funding; Geography; Immunoassay; Individual; Infection; Intervention; Laboratories; Liver; Low Prevalence; Malaria; Measures; Methods; Microscopy; Molecular; Myanmar; Nature; Outcome; Parasites; Peptides; Plasmodium falciparum; Plasmodium vivax; Population; Prevalence; Proteins; Rapid diagnostics; Research; Risk; Sampling; Serology; Serology test; Testing; Time; United States National Institutes of Health; Variant; Work; antigen detection; assay development; base; biomarker discovery; density; design; detection method; diagnostic accuracy; field study; individual response; magnetic beads; malaria infection; malaria transmission; novel; point of care; serological marker; surveillance data; tool; transmission process

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.

项目总结/摘要 迫切需要敏感的、可在实地部署的疟疾监测工具，以指导最佳的 在传播为重点且疟疾风险各异的消灭区部署干预措施。 超灵敏的分子方法已经揭示，在这些环境中的大多数疟疾感染是亚临床的， 低密度感染，这是无法检测到的标准诊断测试，作为一个沉默的水库， 疟疾传播。然而，超灵敏的分子方法是昂贵的，耗时的，需要良好的- 装备的实验室，因此不能提供接触点结果，限制了它们在偏远疟疾中的效用， 地方病流行区。理想的监测工具不仅要测量寄生虫的流行率， 疟疾暴露，提供了一个更强大的表征疟疾的人口。抗体生物标志物是 在这种情况下，疟疾监测的目标是有希望的，因为它们可以指示累积暴露， 易于集成到现有的即时护理平台中。然而，血清学标记物仍然未得到充分利用， 缺乏明确的目标或对如何解释结果的共识。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性的混杂结果。 这项工作建议利用这种多样性来确定信息丰富的抗体生物标志物，以估计疟疾 exposure.根据我们的初步数据，这一提议的中心假设是， 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 和当前暴露。该假设将通过以下特定目的进行检验：1）鉴定抗体 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，和2）使用基于多重珠粒的 免疫测定格式。在目的1中，将通过测量匹配的抗体的血清反应性来鉴定抗体生物标志物。 暴露和未暴露的个体在新的超密集肽阵列上， 恶性疟原虫和间日疟原虫抗原变异体来自参考菌株和地理位置- 相关的田间分离株。在目标2中，向下选择的肽将被批量合成并缀合至条形码化的肽。 用于基于多重荧光的免疫测定的磁珠。对肽靶标的血清反应性将是 对来自已知接触过疟疾和地方性疟疾的个人的充分表征的样本进行测量 对照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， 描述疟疾传播和风险的特征，最终能够更好、更准确地确定干预措施的目标。