ROLE OF COMPLEMENT RECEPTOR 1 IN ERYTHROCYTE INVASION BY PLASMODIUM FALCIPARUM IN

补体受体 1 在恶性疟原虫红细胞侵袭中的作用

• 批准号: 8440204
• 负责人: Gordon Akanzuwine Awandare
• 金额: $ 4.84万
• 依托单位: NOGUCHI MEMORIAL INSTITUTE / MEDICAL RES
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-08 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8440204
• 关键词: Accounting; Acute; Address; Antibodies; Binding; Blood; Cell Surface Proteins; Child; Clinical; Complement Receptor; Country; Dependency; Development; Disease; Doctor of Philosophy; Enzyme-Linked Immunosorbent Assay; Erythrocytes; Falciparum Malaria; Family; Flow Cytometry; Foundations; Gene Expression; Ghana; Glycophorin; Homologous Gene; Immune; Immune response; Individual; Infection; Infectious Diseases Research; Institution; International; Intervention; Invaded; Investigation; Laboratories; Ligands; Malaria; Measures; Mediating; Mediator of activation protein; Molecular; Morbidity - disease rate; Neuraminidase; Outpatients; Parasitemia; Parasites; Pathway interactions; Peripheral; Phenotype; Plasmodium falciparum; Proteins; Public Health; Recruitment Activity; Relative (related person); Reliance; Research; Research Infrastructure; Reticulocytes; Reverse Transcriptase Polymerase Chain Reaction; Role; Sialic Acids; Staging; Statistical Models; Surface; Symptoms; Technology; Testing; Time; Trypsin; Universities; Vaccines; Visit; antigen antibody binding; antigen binding; career; chymotrypsin; density; design; erythrocyte receptor; improved; mortality; parasite invasion; population health; post-doctoral training; pressure; prevent; receptor; transmission process

DESCRIPTION (provided by applicant): A major pathway used by the malaria parasite for invasion is mediated by sialic acid (SA) residues of glycophorins present on the erythrocyte surface and the erythrocyte binding antigen (EBA) family of parasite proteins. However, some P. falciparum strains have the ability to invade neuraminidase-treated erythrocytes which lack SA, demonstrating the existence of alternative SA-independent invasion mechanisms. The erythrocyte receptors that mediate SA-independent invasion had previously been unknown until we recently identified complement receptor 1 (CR1) as the major SA-independent invasion receptor used by laboratory strains of P. falciparum. Subsequent studies have implicated the P. falciparum protein reticulocyte-binding like homologue 4 (Rh4) as the ligand for CR1. This application will extend our investigations to clinical isolates of P. falciparum in Ghana to examine the molecular mechanisms used by field parasites for invasion of erythrocytes in semi-immune individuals and to determine the changes in invasion phenotypes that allow the parasites to evade the adaptive immune response. Parasite isolates collected from three geographically distinct zones of Ghana with varying transmission intensities will be examined for their erythrocyte invasion mechanisms by testing their ability to invade erythrocytes treated with neuraminidase, trypsin, or chymotrypsin, which selectively disrupt specific erythrocyte receptors. In addition, the contribution of CR1 as a receptor will be investigated by measuring the ability of anti-CR1 antibodies and soluble CR1 to inhibit erythrocyte invasion. Erythrocyte CR1 expression in semi-immune individuals will also be measured by flow cytometry and the association with peripheral parasite density will be investigated. In addition, titers of antibodies against the major SA-dependent ligands including, EBA-140, EBA-175, and EBA-181, as well as the CR1 ligand Rh4, will be determined by ELISA and their impact on the relationship between CR1 and parasitemia will be examined using a multivariate statistical model. For parasite isolates whose invasion phenotypes are determined, gene expression of the known SA-independent parasite ligands Rh2a, Rh2b, and Rh4, as well as candidate ligands that will be identified in our ongoing investigations of CR1 ligands, will be determined by quantitative real time RT-PCR. The relationship between erythrocyte receptor usage, anti-EBA antibody titers and ligand gene expression will then be examined to definitively show if increased anti-EBA titers are associated with an increased CR1 ligand gene expression and switch to CR1-dependent invasion phenotype. Successful completion of these proposed studies will substantially increase our understanding of the invasion mechanisms that are used by malaria parasites in Ghana which has broad implications on the design of potential blood- stage interventions.

描述（由申请人提供）：疟疾寄生虫入侵的主要途径是由红细胞表面存在的糖蛋白的唾液酸（SA）残基和寄生虫蛋白的红细胞结合抗原（EBA）家族介导的。然而，一些恶性疟原虫菌株能够侵入经神经氨酸酶处理且缺乏SA的红细胞，这表明存在另一种不依赖于SA的侵入机制。介导 SA 独立入侵的红细胞受体以前一直未知，直到我们最近确定补体受体 1 (CR1) 是恶性疟原虫实验室菌株使用的主要 SA 独立入侵受体。随后的研究表明，恶性疟原虫网织红细胞结合蛋白同源物 4 (Rh4) 是 CR1 的配体。该应用将把我们的研究扩展到加纳的恶性疟原虫临床分离株，以检查野外寄生虫入侵半免疫个体红细胞的分子机制，并确定允许寄生虫逃避适应性免疫的入侵表型的变化。回复。从加纳三个不同地理区域收集的具有不同传播强度的寄生虫分离株，将通过测试其侵入经神经氨酸酶、胰蛋白酶或糜蛋白酶处理的红细胞的能力来检查其红细胞侵入机制，神经氨酸酶、胰蛋白酶或胰凝乳蛋白酶选择性地破坏特定的红细胞受体。此外，将通过测量抗CR1抗体和可溶性CR1抑制红细胞侵袭的能力来研究CR1作为受体的贡献。半免疫个体中的红细胞 CR1 表达也将通过流式细胞术测量，并研究与外周寄生虫密度的关联。此外，针对主要 SA 依赖性配体（包括 EBA-140、EBA-175 和 EBA-181）以及 CR1 配体 Rh4 的抗体滴度将通过 ELISA 测定，及其对 CR1 和 CR1 之间关系的影响。将使用多元统计模型检查寄生虫血症。对于入侵表型已确定的寄生虫分离株，将通过定量实时确定已知的 SA 独立寄生虫配体 Rh2a、Rh2b 和 Rh4 以及将在我们正在进行的 CR1 配体研究中鉴定的候选配体的基因表达逆转录聚合酶链反应。然后将检查红细胞受体使用、抗 EBA 抗体滴度和配体基因表达之间的关系，以明确显示抗 EBA 滴度增加是否与 CR1 配体基因表达增加以及转变为 CR1 依赖性入侵表型相关。成功完成这些拟议的研究将大大增加我们对加纳疟原虫入侵机制的了解，这对潜在血液阶段干预措施的设计具有广泛的影响。