Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
Department of Biological Sciences, Pwani University, Kilifi, Kenya.
PLoS Pathog. 2021 Dec 6;17(12):e1010133. doi: 10.1371/journal.ppat.1010133. eCollection 2021 Dec.
Combinations of monoclonal antibodies (mAbs) against different epitopes on the same antigen synergistically neutralize many viruses. However, there are limited studies assessing whether combining human mAbs against distinct regions of the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) enhances in vivo protection against malaria compared to each mAb alone or whether passive transfer of PfCSP mAbs would improve protection following vaccination against PfCSP. Here, we isolated a panel of human mAbs against the subdominant C-terminal domain of PfCSP (C-CSP) from a volunteer immunized with radiation-attenuated Pf sporozoites. These C-CSP-specific mAbs had limited binding to sporozoites in vitro that was increased by combination with neutralizing human "repeat" mAbs against the NPDP/NVDP/NANP tetrapeptides in the central repeat region of PfCSP. Nevertheless, passive transfer of repeat- and C-CSP-specific mAb combinations did not provide enhanced protection against in vivo sporozoite challenge compared to repeat mAbs alone. Furthermore, combining potent repeat-specific mAbs (CIS43, L9, and 317) that respectively target the three tetrapeptides (NPDP/NVDP/NANP) did not provide additional protection against in vivo sporozoite challenge. However, administration of either CIS43, L9, or 317 (but not C-CSP-specific mAbs) to mice that had been immunized with R21, a PfCSP-based virus-like particle vaccine that induces polyclonal antibodies against the repeat region and C-CSP, provided enhanced protection against sporozoite challenge when compared to vaccine or mAbs alone. Collectively, this study shows that while combining mAbs against the repeat and C-terminal regions of PfCSP provide no additional protection in vivo, repeat mAbs do provide increased protection when combined with vaccine-induced polyclonal antibodies. These data should inform the implementation of PfCSP human mAbs alone or following vaccination to prevent malaria infection.
针对同一抗原上不同表位的单克隆抗体(mAbs)组合可协同中和许多病毒。然而,目前还很少有研究评估将针对疟原虫(Pf)环子孢子蛋白(CSP)不同区域的人源 mAbs 组合使用是否比单独使用每种 mAb 更能增强体内对疟疾的保护作用,或者被动转移 PfCSP mAbs 是否会在 PfCSP 疫苗接种后改善保护作用。在这里,我们从一名接受辐射减毒 Pf 孢子虫免疫的志愿者中分离出一组针对 PfCSP 亚结构域 C 端结构域(C-CSP)的人源 mAbs。这些 C-CSP 特异性 mAbs 在体外与孢子虫的结合有限,与针对 PfCSP 中央重复区 NPDP/NVDP/NANP 四肽的中和性人“重复”mAbs 组合使用可增加结合。然而,与单独使用重复 mAbs 相比,被动转移重复和 C-CSP 特异性 mAb 组合并不能提供针对体内孢子虫挑战的增强保护作用。此外,组合具有针对三个四肽(NPDP/NVDP/NANP)的强效重复特异性 mAbs(CIS43、L9 和 317)并不能提供针对体内孢子虫挑战的额外保护作用。然而,在已接种 R21 的小鼠中,R21 是一种基于 PfCSP 的病毒样颗粒疫苗,可诱导针对重复区和 C-CSP 的多克隆抗体,与疫苗或 mAbs 单独使用相比,给予 CIS43、L9 或 317(但不是 C-CSP 特异性 mAbs)可增强对孢子虫挑战的保护作用。总的来说,这项研究表明,虽然针对 PfCSP 的重复和 C 端区域的 mAbs 组合在体内不能提供额外的保护作用,但当与疫苗诱导的多克隆抗体组合使用时,重复 mAbs 确实提供了增强的保护作用。这些数据应有助于指导 PfCSP 人源 mAbs 的单独使用或接种疫苗以预防疟疾感染。
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