Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, Shanghai, 200240, China; School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 200240, China.
Department of Respiratory and Critical Care Medicine, Zhengzhou University People's Hospital/Henan Provincial People's Hospital, Zhengzhou, 450003, China.
Virol Sin. 2022 Dec;37(6):860-873. doi: 10.1016/j.virs.2022.11.005. Epub 2022 Nov 19.
New variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appear rapidly every few months. They have showed powerful adaptive ability to circumvent the immune system. To further understand SARS-CoV-2's adaptability so as to seek for strategies to mitigate the emergence of new variants, herein we investigated the viral adaptation in the presence of broadly neutralizing antibodies and their combinations. First, we selected four broadly neutralizing antibodies, including pan-sarbecovirus and pan-betacoronavirus neutralizing antibodies that recognize distinct conserved regions on receptor-binding domain (RBD) or conserved stem-helix region on S2 subunit. Through binding competition analysis, we demonstrated that they were capable of simultaneously binding. Thereafter, a replication-competent vesicular stomatitis virus pseudotyped with SARS-CoV-2 spike protein was employed to study the viral adaptation. Twenty consecutive passages of the virus under the selective pressure of individual antibodies or their combinations were performed. It was found that it was not hard for the virus to adapt to broadly neutralizing antibodies, even for pan-sarbecovirus and pan-betacoronavirus antibodies. The virus was more and more difficult to escape the combinations of two/three/four antibodies. In addition, mutations in the viral population revealed by high-throughput sequencing showed that under the selective pressure of three/four combinational antibodies, viral mutations were not prone to present in the highly conserved region across betacoronaviruses (stem-helix region), while this was not true under the selective pressure of single/two antibodies. Importantly, combining neutralizing antibodies targeting RBD conserved regions and stem helix synergistically prevented the emergence of escape mutations. These studies will guide future vaccine and therapeutic development efforts and provide a rationale for the design of RBD-stem helix tandem vaccine, which may help to impede the generation of novel variants.
新型严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 变异株每隔几个月就会迅速出现。它们表现出强大的适应性，能够规避免疫系统。为了进一步了解 SARS-CoV-2 的适应性，以寻求减轻新变异株出现的策略，在此我们研究了在广泛中和抗体及其组合存在下的病毒适应性。首先，我们选择了四种广泛中和抗体，包括识别受体结合域（RBD）上不同保守区域或 S2 亚基上保守茎-螺旋区域的泛 SARS-CoV 和泛β冠状病毒中和抗体。通过结合竞争分析，我们证明它们能够同时结合。此后，我们使用带有 SARS-CoV-2 刺突蛋白的复制型水疱性口炎病毒假型来研究病毒适应性。在单独抗体或其组合的选择性压力下连续进行了 20 次病毒传代。结果发现，病毒适应广泛中和抗体并不难，即使是针对泛 SARS-CoV 和泛β冠状病毒的抗体。病毒越来越难以逃避两种/三种/四种抗体的组合。此外，高通量测序揭示的病毒群体中的突变表明，在三种/四种组合抗体的选择性压力下，病毒突变不太可能出现在β冠状病毒（茎-螺旋区域）的高度保守区域，而在单一/两种抗体的选择性压力下则不是这样。重要的是，针对 RBD 保守区域和茎螺旋的中和抗体联合使用可协同阻止逃逸突变的出现。这些研究将指导未来的疫苗和治疗开发工作，并为设计 RBD-茎螺旋串联疫苗提供理论依据，这可能有助于阻止新变异株的产生。
