Extent, dynamics and mechanisms of Plasmodium vivax immune evasion caused by PvDBP gene amplification

PvDBP基因扩增引起间日疟原虫免疫逃避的程度、动态及机制

• 批准号: 10734028
• 负责人: Eugenia Lo
• 金额: $ 62.62万
• 依托单位: INSTITUT PASTEUR DU CAMBODGE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-17 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10734028
• 关键词: Adult; Alleles; Antibodies; Area; Biomass; Blood; Cambodia; Cambodian; Child; Clinical; Data; Development; Diagnostic; Distant; Eastern Africa; Enrollment; Epidemiology; Epitopes; Erythrocytes; Ethiopia; Evolution; Exposure to; Flow Cytometry; Frequencies; Gene Amplification; Genes; Genetic; Genetic Polymorphism; Genomic approach; Genomics; Goals; Human; Humoral Immunities; Immune Evasion; Immunity; Immunoglobulin G; Immunologic Tests; In Vitro; Individual; Infection; Invaded; Length; Ligands; Longitudinal cohort; Malaria; Malaria Vaccines; Measures; Mediating; Molecular; Parasitemia; Parasites; Participant; Phase II Clinical Trials; Phenotype; Plasmodium vivax; Population; Population Dynamics; Prevalence; Process; Protein Isoforms; Proteins; Serology; Severity of illness; Side; Southeastern Asia; Structure; Surface; Testing; Time; Transcend; Transgenic Organisms; Vaccines; Variant; Vivax Malaria; Western Blotting; Work; deep sequencing; design; follow-up; human monoclonal antibodies; immunological status; in vivo; live cell imaging; neutralizing antibody; participant enrollment; pathogen; phase II trial; prospective test; receptor; resilience; response; success; time use; transcriptome sequencing; vaccine development; vaccine strategy

Elimination of Plasmodium vivax (Pv) malaria parasites would greatly benefit from a blood-stage vaccine. PvDBP is a parasite ligand involved in erythrocyte invasion through the interaction with its human receptor, the Duffy protein. This interaction is critical for the parasite’s entry making PvDBP the most advanced candidate for a blood-stage vaccine with Phase II clinical trials undergoing. Recent work has identified and characterized human monoclonal antibodies (humabs) that allow strain-transcending neutralization of parasites regardless of their PvDBP sequence diversity. However, we have demonstrated that Pv collected in Cambodia with multiple copies of the PvDBP gene were able to overcome in vitro neutralization by these humabs. These observations provided the first evidence for an evolutionary advantage for pvdbp amplification, widespread in Pv populations, and created a new paradigm in which to consider pathogen immune evasion mechanisms. These results raise the concern that implementation of a PvDBP vaccine may select for multi-pvdbp copy parasites. The overall goal of this proposal is precisely to determine if pvdbp amplification will likely compromise a PvDBP vaccine strategy. The first Specific Aim (SA) is to determine to what extent multi-pvdbp copy parasites genetically distant from Cambodian isolates respond to anti-PvDBP humabs and to evaluate if pvdbp amplification is associated to Duffy polymorphisms in human populations. By evaluating the in vitro neutralization by anti-PvDBP humabs of single and multi-pvdbp copy parasites from Ethiopia, we will be able to evaluate the extent of the immune evasion phenotype conferred by pvdbp amplification described with Cambodian Pv. By (i) associating in vitro invasion rates with the full-length Duffy sequences of invaded erythrocytes, and (ii) prospectively testing for association between pvdbp copy number and human Duffy sequences in participants enrolled in longitudinal cohorts in Cambodia and in Ethiopia, we will be able to determine the relation between pvdbp amplification and Duffy human polymorphism. Our second SA will be to evaluate the within-hosts and within-population dynamics of pvdbp amplification over time. Through the analysis of the serological dynamics of our longitudinal cohorts’ participants, the measure of Pv infections and the pvdbp copy number of infecting parasites, we will be able to test if the gene amplification is selected in vivo by the immune status of human hosts and how it correlates with changes in Pv prevalence in the population. In vitro experimental evolution of Pk lines will provide complementary evidence for selection of pvdbp amplification by anti-PvDBP humabs. Our third SA will be to decipher the molecular mechanisms enabling multi-copy parasites to evade anti-PvDBP humabs’ neutralization. We will specifically test if immune evasion results from increased protein quantity produced by multi-copy parasites and/or from epitope variations through multiple, different alleles and variants present simultaneously in a given parasite. Through a combination of phenotyping and genomic approaches, our results will provide invaluable data to inform on strategies to overcome this immune evasion in the context of vaccine development. .

消除体内疟原虫（PV）疟疾寄生虫将从血阶段疫苗中受益匪浅。 PVDBP 是通过与人类受体的互动涉及红细胞侵袭的寄生虫配体 蛋白质。这种互动对于寄生虫的条目至关重要 接受II期临床试验的血级疫苗正在接受。最近的工作已经确定并表征了人类 单克隆抗体（Humabs），允许寄生虫的菌株传递神经化 PVDBP序列多样性。但是，我们已经证明，PV在柬埔寨收集了多个副本 PVDBP基因能够克服这些人的体外神经化。提供了这些观察结果 PVDBP扩增的进化优势的第一个证据，PV人群中的宽度和 创建了一个新的范式，其中考虑了病原体免疫进化机制。这些结果提高了 担心实施PVDBP疫苗可能会选择多PVDBP复制寄生虫。总体目标 该建议的精确是确定PVDBP扩增是否可能损害PVDBP疫苗 战略。第一个特定目的（SA）是确定通常远距离的多pvDBP复制寄生虫 来自柬埔寨分离株对抗PVDBP枢轴的反应，并评估PVDBP放大是否与 人群中的达菲多态性。通过评估抗PVDBP人的体外神经化 来自埃塞俄比亚的单一和多PVDBP复制寄生虫，我们将能够评估免疫进化的程度 由柬埔寨PV描述的PVDBP扩增赋予的表型。通过（i）在体外入侵关联 具有入侵的红细胞的全长达菲序列的速率，以及（ii）缔合的前瞻性测试 在参与者中的PVDBP拷贝数和人类达菲序列之间 柬埔寨和埃塞俄比亚，我们将能够确定PVDBP扩增与达菲的关系 人类多态性。我们的第二个SA将是评估主机内和人口内动力学 PVDBP随着时间的推移。通过分析我们纵向人群的血清学动力学 参与者，光伏感染的测量和受感染寄生虫的PVDBP拷贝数，我们将能够 测试是否通过人类宿主的免疫状态在体内选择基因扩增以及其与其相关的相关性 人口中的PV患病率的变化。 PK系的体外实验演变将提供完整 通过抗PVDBP Hubabs选择PVDBP扩增的证据。我们的第三个SA将是破译 分子机制，使多拷贝寄生虫能够逃避抗PVDBP Hubabs的神经化。我们将 特异性测试免疫进化是否是由于多拷贝寄生虫产生的蛋白质量增加而导致的 和/或来自表位变化，通过多个不同的等位基因和变体很容易在给定的 寄生虫。通过表型和基因组方法的结合，我们的结果将提供宝贵的结果 在疫苗开发的背景下，数据告知要克服这种免疫进化的策略。 。

项目成果

Prevalence and characteristics of Plasmodium vivax Gametocytes in Duffy-positive and Duffy-negative populations across Ethiopia.

埃塞俄比亚达菲阳性和达菲阴性人群中间日疟原虫配子细胞的患病率和特征。

• DOI: 10.1101/2023.12.10.23299780
• 发表时间: 2023
• 期刊: medRxiv : the preprint server for health sciences
• 作者: Little,Ebony;Shenkutie,TassewT;Negash,MesheshaTsigie;Abagero,BekaR;Abebe,Abnet;Popovici,Jean;Mekasha,Sindew;Lo,Eugenia
• 通讯作者: Lo,Eugenia