Intracellular-acting antibodies for the prevention of malaria liver stage infection

用于预防疟疾肝期感染的细胞内作用抗体

• 批准号: 10571407
• 负责人: Brandon Keith Wilder
• 金额: $ 26.95万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-04 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10571407
• 关键词: Anopheles Genus; Antibodies; Antibody titer measurement; Antigens; Antimalarials; Area; Autophagocytosis; Back; Binding; Blood; Cessation of life; Characteristics; Child; Communicable Diseases; Complex; Culicidae; Cytoplasm; Data; Dermis; Disease; Dose; Epitopes; Erythrocytes; Fab Immunoglobulins; Future; Goals; Hepatocyte; Human; Immunity; Infection; Infection prevention; Interruption; Intervention; Kinetics; Knockout Mice; Life Cycle Stages; Liver; Location; Malaria; Malaria Vaccines; Malaria prevention; Mediating; Membrane Proteins; Monoclonal Antibodies; Morbidity - disease rate; Parasites; Passive Transfer of Immunity; Plasmodium; Predisposition; Protein Secretion; Proteins; Publications; Recording of previous events; Regimen; Role; Skin; Sporozoites; Sterility; Subunit Vaccines; Surface; Testing; Therapeutic; Time; Vaccines; Visualization; circumsporozoite protein; extracellular; in vivo; liver infection; mortality; novel; pathogen; polyclonal antibody; prevent; rational design; synergism; transmission process; vaccine candidate; vaccine development; vaccine evaluation; vaccine-induced antibodies; vector

Abstract Malaria, caused by infection with Plasmodium spp., is one of the oldest and most lethal diseases in human history. It continues to be a leading cause of morbidity and mortality, especially amongst children under five. Despite over a decade of progress in reducing the burden of malaria, the last four years have seen a stagnation due to recalcitrance in highly endemic areas and interruptions in eradication efforts. As for any infectious disease, sustained progress will require an effective vaccine. For malaria, antibodies have been shown particularly potent in stopping the “sporozoite” form of Plasmodium during its ~30 minute journey from the mosquito, into the skin and then into a liver hepatocyte. Here, the parasite completes the asymptomatic “pre-erythrocytic” (PE) stages over ~1 week before emerging back into the blood for the erythrocytic stage, where it infects red blood cells and causes all morbidity, mortality and transmission. Stopping the parasite at the PE stage (i.e. sterile protection) is the ultimate goal of a malaria vaccine. Unfortunately, antibody-based vaccine candidates targeting the major surface protein (circumsporozoite protein, CSP) exposed at the sporozoite surface have failed to provide the long-lasting sterile protection needed for sustained control and elimination as this requires extremely high titers of antibodies which can only be maintained over short periods or with frequent boosting. One strategy to enhance CSP-based vaccines is to target additional antigens. However, demonstration that non-CSP targeting antibodies which can function on their own or in concert with CSP has been lacking. Current efforts have focused on surface/secreted proteins exposed during the extracellular sporozoite stage in line with dogma that once the parasite is within the hepatocyte, it is no longer accessible to antibodies. Surprisingly, we have found that antibodies targeting a liver stage-specific protein, UIS3, can efficiently kill the parasite during the intracellular hepatocyte stage. Furthermore, a low dose of these antibodies can synergize with a low dose of anti-CSP antibodies to raise sterile protection from 0% with each antibody alone to 64% in combination. These data not only add to the small number of bona fide PE antibody targets, but also open an entirely new parasite stage for antibody discovery and are the first demonstration of synergy between multiple antigens at the PE stage. While such intracellularly targeted antibodies (iAbs) have been described for other pathogens, their mechanisms of action are not well understood. Here, we aim to use monoclonal antibodies to define the basic functional characteristics of anti-UIS3 antibodies and to identify the core mechanisms of anti-UIS3 iAb action. These data will support the rational design of superior CSP-based vaccines and monoclonal antibody regimens with an iAb component, with the goal that these Ab-based interventions can achieve the high levels of long- lasting sterile protection to drive malaria to elimination.

摘要 疟疾是由疟原虫感染引起的，是人类最古老和最致命的疾病之一 历史它仍然是发病和死亡的主要原因，特别是在五岁以下儿童中。 尽管十多年来在减轻疟疾负担方面取得了进展，但过去四年中， 由于在高度流行地区的抵制和根除工作的中断，至于任何 传染病，持续的进展将需要一种有效的疫苗。对于疟疾， 显示出在疟原虫的“子孢子”形式从 进入皮肤，然后进入肝细胞。在这里，寄生虫完成了无症状的 “红细胞前期”（PE）期超过约1周，然后出现回到血液中用于红细胞期， 在那里它感染红细胞并引起所有的发病率、死亡率和传播。阻止寄生虫 PE阶段（即无菌保护）是疟疾疫苗的最终目标。不幸的是， 靶向暴露于细胞表面的主要表面蛋白（环子孢子蛋白，CSP）的候选疫苗。 子孢子表面不能提供持续控制所需的持久的无菌保护， 因为这需要极高滴度的抗体， 或频繁升压。增强基于CSP的疫苗的一种策略是靶向另外的抗原。 然而，可以单独或与CSP协同发挥作用的非CSP靶向抗体的证明是不可能的。 CSP一直缺乏。目前的努力集中在在细胞生长过程中暴露的表面/分泌蛋白质上。 细胞外子孢子阶段符合一旦寄生虫在肝细胞内，它就不再是 可以接触到抗体令人惊讶的是，我们已经发现，针对肝脏阶段特异性的抗体， 蛋白质UIS 3可以在细胞内肝细胞阶段有效地杀死寄生虫。而且有 低剂量的这些抗体可以与低剂量的抗CSP抗体协同作用， 保护率从每种抗体单独使用时的0%到组合使用时的64%。这些数据不仅增加了 少数真正的PE抗体靶点，但也为寄生虫感染开辟了一个全新的阶段。 抗体的发现，是PE中多种抗原之间协同作用的首次证明 阶段虽然已经描述了用于其他病原体的此类细胞内靶向抗体（iAb），但它们的免疫原性和特异性是已知的。 作用机制还不清楚。在这里，我们的目标是使用单克隆抗体来定义基本的 抗UIS 3抗体的功能特征，并确定抗UIS 3 iAb作用的核心机制。 这些数据将支持基于上级CSP的疫苗和单克隆抗体方案的合理设计 与iAb组件，与目标，这些抗体为基础的干预措施可以实现高水平的长期- 持久的不育保护，以推动消灭疟疾。