Defining conserved epitopes on polymorphic malaria antigens

定义多态性疟疾抗原上的保守表位

• 批准号: 10211754
• 负责人: Evelien Margaretha Bunnik
• 金额: $ 43.42万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-19 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10211754
• 关键词: Adult; Affinity; Antibodies; Antibody Response; Antigens; B cell differentiation; B-Cell Antigen Receptor; B-Cell Development; Binding; Biological Assay; Blood; Cell Lineage; Cessation of life; Characteristics; Child; Clinical; Complex Mixtures; Data; Disease; Engineering; Epitope Mapping; Epitopes; Erythrocytes; Failure; Freezing; Genes; Genetic Polymorphism; Genetic Variation; Immune; Immune response; Immunity; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunologics; Immunology; In Vitro; Individual; Infection; Knowledge; Learning; Life; Life Cycle Stages; Malaria; Malaria Vaccines; Maps; Mass Spectrum Analysis; Memory; Memory B-Lymphocyte; Molecular; Monoclonal Antibodies; Morbidity - disease rate; Mutagenesis; Nature; Parasites; Parasitology; Passive Immunization; Peripheral Blood Mononuclear Cell; Plasma Cells; Plasmodium falciparum; Positioning Attribute; Proteomics; Serology; Serum; Sporozoite vaccine; Sporozoites; Structure; Testing; Transcend; Uganda; Vaccination; Vaccine Design; Vaccines; Variant; X-Ray Crystallography; acquired immunity; base; cohort; design; experience; experimental study; falls; fight against; insight; malaria transmission; mortality; next generation; novel; prevent; response; structural biology; tool; vaccine candidate; vaccine development; vaccine trial

PROJECT SUMMARY Malaria is still responsible for an estimated 429,000 deaths and 212 million infections per year, the large majority among young children. Individuals living in endemic regions gradually develop an immune response that protects against symptomatic disease. Naturally acquired immunity targets the blood stage of the parasite’s life cycle and is largely dependent on antibody reactivity. Elicitation of a similar immune response by vaccination in young, non-immune children would dramatically reduce malaria morbidity and mortality. Various parasite antigens have been associated with protection against clinical disease. Most of these antigens are expressed in the merozoite stage and are involved in invasion of the red blood cell. However, vaccine trials based on these blood-stage antigens have thus far been unsuccessful. One factor contributing to the failure of blood stage vaccines is the extensive genetic diversity between different parasite strains that has resulted in strain-specific, but not strain- transcending, antibody responses. Studies of naturally acquired immunity suggest that protected individuals harbor antibodies against conserved epitopes. The identification of such conserved epitopes could serve as a blueprint for structure-based design of a malaria blood stage vaccine. We hypothesize that immunity against malaria is dependent on high affinity IgGs with cross-strain reactivity against merozoite antigens and that these antibodies can be used to define conserved epitopes on merozoite vaccine candidates. To test this hypothesis, we will compare the molecular and functional characteristics of antibodies directed against merozoite antigens among immune adults, semi-immune children and non-immune children living in Tororo, Uganda, a region with extremely high malaria transmission intensity, and use the most potent and broadly reactive antibodies for epitope mapping. In Specific Aim 1, we will isolate merozoite antigen-specific memory B cells from these individuals, test the ability of these antibodies to inhibit various malaria parasite strains in vitro, and map the epitopes of cross-strain reactive antibodies to define conserved epitopes on merozoite antigens. In Specific Aim 2, we will deep-sequence the memory B cell receptor repertoire to uncover the impact of life-long malaria exposure on the humoral immune response, analyze the repertoire of anti-merozoite serum antibodies and determine the cross-strain inhibitory activity and epitopes of dominant serum antibody clonotypes. Collectively, the results from these experiments will provide detailed information about the types of antibodies that a blood-stage vaccine should ideally elicit and will enable the design of novel immunogens to elicit strain- transcending antibodies against the malaria blood stage. In addition, it will provide insight into the overlap and differences between the memory B cell and serological compartments, and the selective mechanisms that drive B cell differentiation into plasma cells and memory B cells.

项目总结 疟疾每年仍造成约42.9万人死亡和2.12亿人感染，占绝大多数 在年幼的孩子中。生活在流行地区的个人逐渐产生一种免疫反应，以保护 对抗症状性疾病。自然获得性免疫针对寄生虫生命周期的血液阶段， 在很大程度上取决于抗体的反应性。通过接种疫苗在年轻的， 没有免疫能力的儿童将极大地降低疟疾发病率和死亡率。各种寄生虫抗原都有 与预防临床疾病有关。这些抗原大多在裂殖子中表达。 并参与红血球的入侵。然而，基于这些血液阶段的疫苗试验 到目前为止，抗原还没有成功。导致血液期疫苗失败的一个因素是 不同寄生虫菌株之间广泛的遗传多样性导致了菌株特有，但不是菌株- 超越，抗体反应。对自然获得性免疫的研究表明，受保护的个体 保护针对保守表位的抗体。这种保守表位的鉴定可以作为一种 基于结构的疟疾血液期疫苗设计蓝图。我们假设对病毒的免疫力 疟疾依赖于对裂殖子抗原具有跨株反应性的高亲和力免疫球蛋白和 这些抗体可以用来定义裂殖子疫苗候选的保守表位。为了测试 这一假设，我们将比较分子和功能特性的抗体针对 居住在托罗罗的免疫成人、半免疫儿童和非免疫儿童中的裂殖子抗原， 乌干达，一个疟疾传播强度极高的地区，并使用最有效和最广泛的 用于表位定位的反应性抗体。在特定的目标1中，我们将分离裂殖子抗原特异性记忆B 来自这些个体的细胞，在体外测试这些抗体抑制各种疟疾寄生虫株的能力， 并绘制跨株反应性抗体的表位图，以定义裂殖子抗原上的保守表位。在……里面 特定目标2，我们将对记忆B细胞受体谱系进行深度测序，以揭示其对终身的影响 疟疾暴露对体液免疫应答的影响，分析抗裂殖子血清抗体谱 并测定优势血清抗体克隆型的跨株抑制活性和表位。 总的来说，这些实验的结果将提供有关抗体类型的详细信息 理想情况下，血液期疫苗应该诱导并将使新型免疫原的设计能够诱导出菌株- 超越疟疾血液期的抗体。此外，它还将提供对重叠和 记忆B细胞和血清学隔间的差异以及驱动的选择机制 B细胞分化为浆细胞和记忆性B细胞。