Antibodies against a short region of PfRipr inhibit Plasmodium falciparum merozoite invasion and PfRipr interaction with Rh5 and SEMA7A
Antibodies against a short region of PfRipr inhibit Plasmodium falciparum merozoite invasion and PfRipr interaction with Rh5 and SEMA7A
复制标题
DOI：
10.1038/s41598-020-63611-6
复制
发表时间：
2020-04-20
影响因子：
4.6
通讯作者：
Takashima, Eizo
中科院分区：
文献类型：
--
作者：
Nagaoka, Hikaru;Kanoi, Bernard N.;Takashima, Eizo
恶性疟原虫裂殖子侵入红细胞是血液阶段循环、寄生虫存活和疟疾发病的重要步骤。恶性疟原虫裂殖子Rh 5相互作用蛋白（PfRipr）与Rh 5和CyRPA在导致红细胞侵袭的连续分子事件中形成复合物。最近，我们描述PfRipr作为一个保守的蛋白质，诱导应变超越生长抑制抗体在体外测定。然而，PfRipr是一种含有87个半胱氨酸残基的1086个氨基酸（aa）的大而复杂的蛋白质，难以在用于疫苗开发的常规表达系统中表达。在这项研究中，我们试图确定PfRipr的最有效的区域，可以开发克服与蛋白质表达相关的困难，以及阐明抗PfRipr抗体的侵袭抑制机制。使用麦胚无细胞系统，将Ecto-PfRipr和约200个氨基酸的截短物表达为可溶性蛋白。我们证明了针对PfRipr截短物5（PfRipr_5：C-720-D-934）（PfRipr C末端EGF样结构域内的区域）的抗体有效地抑制裂殖子侵入。此外，抗体强烈阻断PfRipr/Rh 5相互作用，以及PfRipr与其红细胞表面受体SEMA 7A之间的相互作用。综上所述，PfRipr_5是进一步开发作为血液阶段疟疾疫苗的潜在候选者。
Plasmodium falciparum merozoite invasion into erythrocytes is an essential step of the blood-stage cycle, survival of parasites, and malaria pathogenesis. P. falciparum merozoite Rh5 interacting protein (PfRipr) forms a complex with Rh5 and CyRPA in sequential molecular events leading to erythrocyte invasion. Recently we described PfRipr as a conserved protein that induces strain-transcending growth inhibitory antibodies in in vitro assays. However, being a large and complex protein of 1086 amino acids (aa) with 87 cysteine residues, PfRipr is difficult to express in conventional expression systems towards vaccine development. In this study we sought to identify the most potent region of PfRipr that could be developed to overcome difficulties related to protein expression, as well as to elucidate the invasion inhibitory mechanism of anti-PfRipr antibodies. Using the wheat germ cell-free system, Ecto- PfRipr and truncates of approximately 200 aa were expressed as soluble proteins. We demonstrate that antibodies against PfRipr truncate 5 (PfRipr_5: C-720-D-934), a region within the PfRipr C-terminal EGF-like domains, potently inhibit merozoite invasion. Furthermore, the antibodies strongly block PfRipr/Rh5 interaction, as well as that between PfRipr and its erythrocyte-surface receptor, SEMA7A. Taken together, PfRipr_5 is a potential candidate for further development as a blood-stage malaria vaccine.