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. .

消灭间日疟原虫（Pv）疟疾寄生虫将大大受益于血液阶段疫苗。PvDBP 是一种寄生虫配体，通过与其人类受体达菲相互作用参与红细胞侵入 蛋白这种相互作用对于寄生虫的进入至关重要，使PvDBP成为最先进的候选者。 血液阶段疫苗，正在进行第二阶段临床试验。最近的工作已经确定并表征了人类 单克隆抗体（humab），允许超越菌株的寄生虫中和，而不管它们的 PvDBP序列多样性。然而，我们已经证明，在柬埔寨收集的Pv有多个副本， 的PvDBP基因能够克服体外中和这些humab。这些意见提供了 pvdbp扩增具有进化优势的第一个证据，广泛存在于Pv种群中， 创造了一个新的范式，考虑病原体免疫逃避机制。这些结果提高了 担心实施PvDBP疫苗可能选择多拷贝的pvDBP寄生虫。总目标 该提议的目的是确定pvDBP扩增是否可能损害PvDBP疫苗 战略第一个特定目的（SA）是确定多pvdbp拷贝寄生虫遗传距离的程度 柬埔寨分离株对抗PvDBP humab应答，并评估pvDBP扩增是否与 人类群体中的Duffy多态性。通过评价抗PvDBP humab的体外中和作用， 单和多pvdbp副本寄生虫从埃塞俄比亚，我们将能够评估免疫逃避的程度 柬埔寨Pv.通过（i）将体外侵袭 率与入侵红细胞的全长Duffy序列，和（ii）前瞻性测试的关联 pvdbp拷贝数和人Duffy序列之间的关系， 在柬埔寨和埃塞俄比亚，我们将能够确定pvdbp扩增和达菲之间的关系， 人类多态性我们的第二个SA将是评估宿主内和种群内的动态， pvDBP随时间的扩增。通过对我们的纵向队列的血清学动态分析， 参与者，Pv感染的测量和感染寄生虫的pvdbp拷贝数，我们将能够 测试基因扩增是否是由人类宿主的免疫状态在体内选择的，以及它与 人群中PV患病率的变化。PK系的体外实验进化将提供补充 通过抗PvDBP humab选择pvDBP扩增的证据。我们的第三个SA将破译 使多拷贝寄生虫能够逃避抗PvDBP humab中和的分子机制。我们将 特异性测试免疫逃避是否由多拷贝寄生虫产生的蛋白质量增加引起 和/或通过在给定的表位中同时存在的多个不同的等位基因和变体的表位变异 寄生虫通过表型分析和基因组学方法的结合，我们的结果将提供宝贵的 数据，以告知在疫苗开发的背景下克服这种免疫逃避的策略。 .

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