Department of Immunology, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, People's Republic of China.
State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, People's Republic of China.
Int J Nanomedicine. 2023 Oct 16;18:5781-5795. doi: 10.2147/IJN.S427990. eCollection 2023.
The emergence of the coronavirus disease 2019 (COVID-19) pandemic and the new severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern (VOCs) requires the continuous development of safe, effective, and affordable prevention and therapeutics. Nanobodies have demonstrated antiviral activity against a variety of viruses, providing a new candidate for the prevention and treatment of SARS-CoV-2 and its variants.
SARS-CoV-2 glycoprotein spike 1 subunit (S1) was selected as the target antigen for nanobody screening of a naïve phage display library. We obtained a nanobody, named Nb-H6, and then determined its affinity, inhibition, and stability by ELISA, Competitive ELISA, and Biolayer Interferometry (BLI). Infection assays of authentic and pseudotyped SARS-CoV-2 were performed to evaluate the neutralization of Nb-H6. The structure and mechanism of action were investigated by AlphaFold, docking, and residue mutation assays.
We isolated and characterized a nanobody, Nb-H6, which exhibits a broad affinity for S1 and the receptor binding domain (RBD) of SARS-CoV-2, or Alpha (B.1.1.7), Delta (B.1.617.2), Lambda (C.37), and Omicron (BA.2 and BA.5), and blocks receptor angiotensin-converting enzyme 2 (ACE2) binding. Moreover, Nb-H6 can retain its binding capability after pH or thermal treatment and effectively neutralize both pseudotyped and authentic SARS-CoV-2, as well as VOC Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (BA.2 and BA.5) pseudoviruses. We also confirmed that Nb-H6 binds two distinct amino acid residues of the RBD, preventing SARS-CoV-2 from interacting with the host receptor.
Our study highlights a novel nanobody, Nb-H6, that may be useful therapeutically in SARS-CoV-2 and VOC outbreaks and pandemics. These findings also provide a molecular foundation for further studies into how nanobodies neutralize SARS-CoV-2 and variants and imply potential therapeutic targets for the treatment of COVID-19.
2019 年冠状病毒病（COVID-19）大流行和新的严重急性呼吸系统综合征冠状病毒 2（SARS-CoV-2）关切变异株（VOC）的出现，需要不断开发安全、有效和负担得起的预防和治疗方法。纳米抗体已被证明对多种病毒具有抗病毒活性，为预防和治疗 SARS-CoV-2 及其变体提供了新的候选物。
选择 SARS-CoV-2 糖蛋白刺突 1 亚单位（S1）作为针对原始噬菌体展示文库的纳米抗体筛选的靶抗原。我们获得了一个纳米抗体，命名为 Nb-H6，然后通过 ELISA、竞争 ELISA 和生物层干涉（BLI）测定其亲和力、抑制作用和稳定性。进行真实和假型 SARS-CoV-2 的感染实验以评估 Nb-H6 的中和作用。通过 AlphaFold、对接和残基突变实验研究结构和作用机制。
我们分离并鉴定了一个纳米抗体，Nb-H6，它对 SARS-CoV-2 的 S1 和受体结合域（RBD），或 Alpha（B.1.1.7）、Delta（B.1.617.2）、Lambda（C.37）和 Omicron（BA.2 和 BA.5）具有广泛的亲和力，并阻断受体血管紧张素转换酶 2（ACE2）结合。此外，Nb-H6 可以在 pH 或热处理后保持其结合能力，并有效中和真实和假型 SARS-CoV-2，以及 VOC Alpha（B.1.1.7）、Delta（B.1.617.2）和 Omicron（BA.2 和 BA.5）假病毒。我们还证实，Nb-H6 结合 RBD 的两个不同氨基酸残基，阻止 SARS-CoV-2 与宿主受体相互作用。
我们的研究强调了一种新型纳米抗体 Nb-H6，它可能在 SARS-CoV-2 和 VOC 爆发和大流行期间具有治疗用途。这些发现还为进一步研究纳米抗体如何中和 SARS-CoV-2 和变体提供了分子基础，并暗示了 COVID-19 治疗的潜在治疗靶点。
