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. .

消除间日疟原虫 (Pv) 疟疾寄生虫将大大受益于 PvDBP 血液阶段疫苗。 是一种寄生虫配体，通过与其人类受体 Duffy 相互作用参与红细胞侵袭 这种相互作用对于寄生虫的进入至关重要，使得 PvDBP 成为最先进的候选蛋白。 正在进行二期临床试验的血期疫苗已在人体中进行了鉴定和表征。 单克隆抗体（humab）可以超越菌株中和寄生虫，无论其寄生虫如何 然而，我们已经证明 Pv 在柬埔寨收集有多个拷贝。 PvDBP 基因的突变能够克服这些 humab 的体外中和作用。 pvdbp 扩增具有进化优势的第一个证据，广泛存在于 Pv 群体中，以及 创建了一个考虑病原体免疫逃避机制的新范式。 担心 PvDBP 疫苗的实施可能会选择多 pvdbp 复制寄生虫。 该提案的目的正是为了确定 pvdbp 扩增是否可能损害 PvDBP 疫苗 第一个具体目标 (SA) 是确定多 pvdbp 复制寄生虫在遗传上的疏远程度。 柬埔寨分离株对抗 PvDBP humabs 有反应，并评估 pvdbp 扩增是否与 通过评估抗 PvDBP humab 的体外中和作用，在人群中进行 Duffy 多态性。 来自埃塞俄比亚的单个和多个 pvdbp 复制寄生虫，我们将能够评估免疫逃避的程度 由柬埔寨 Pv 描述的 pvdbp 扩增赋予的表型通过 (i) 关联体外入侵。 率与入侵红细胞的全长达菲序列的比率，以及（ii）前瞻性测试关联 在参加纵向队列的参与者中，pvdbp 拷贝数和人类 Duffy 序列之间的差异 在柬埔寨和埃塞俄比亚，我们将能够确定pvdbp放大和Duffy之间的关系 我们的第二个 SA 将评估宿主内和群体内的动态。 通过分析我们纵向队列的血清学动态，pvdbp 随着时间的推移而扩增。 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通过人类宿主的免疫状态在体内选择的，以及它与 Pk 品系的体外实验进化将提供补充。 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 humabs 中和的分子机制。 特别测试免疫逃避是否是由多拷贝寄生虫产生的蛋白质数量增加引起的 和/或通过在给定中同时存在的多个不同等位基因和变体的表位变异 通过结合表型分析和基因组方法，我们的结果将提供无价的价值。 数据可为疫苗开发中克服这种免疫逃避的策略提供信息。 。

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