Novel bispecific human antibody platform specifically targeting a fully open spike conformation potently neutralizes multiple SARS-CoV-2 variants

• Published in: Antiviral research 2023-04, Vol.212, p.105576-105576, Article 105576
• Main Authors: Kim, Ji Woong, Heo, Kyun, Kim, Hyun Jung, Yoo, Youngki, Cho, Hyun-Soo, Jang, Hui Jeong, Lee, Ho-Young, Ko, In Young, Woo, Ju Rang, Cho, Yea Bin, Lee, Ji Hyun, Yang, Ha Rim, Shin, Ha Gyeong, Choi, Hye Lim, Hwang, Kyusang, Kim, Sokho, Kim, Hanseong, Chun, Kwangrok, Lee, Sukmook
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Bispecific - pharmacology; Antibodies, Neutralizing; Antibodies, Viral; Bispecific antibody; COVID-19; Cryo-EM; Cryoelectron Microscopy; Humans; Immunoglobulin G4; Mice; Phage display; SARS-CoV-2 - metabolism; SARS-CoV-2 variants; Spike Glycoprotein, Coronavirus; Structural analysis
• ISSN: 0166-3542; 1872-9096
• DOI: 10.1016/j.antiviral.2023.105576

Rapid emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has prompted an urgent need for the development of broadly applicable and potently neutralizing antibody platform against the SARS-CoV-2, which can be used for combatting the coronavirus disease 2019 (COVID-19). In this study, based on a noncompeting pair of phage display-derived human monoclonal antibodies (mAbs) specific to the receptor-binding domain (RBD) of SARS-CoV-2 isolated from human synthetic antibody library, we generated K202.B, a novel engineered bispecific antibody with an immunoglobulin G4-single-chain variable fragment design, with sub- or low nanomolar antigen-binding avidity. Compared with the parental mAbs or mAb cocktail, the K202.B antibody showed superior neutralizing potential against a variety of SARS-CoV-2 variants in vitro. Furthermore, structural analysis of bispecific antibody-antigen complexes using cryo-electron microscopy revealed the mode of action of K202.B complexed with a fully open three-RBD-up conformation of SARS-CoV-2 trimeric spike proteins by simultaneously interconnecting two independent epitopes of the SARS-CoV-2 RBD via inter-protomer interactions. Intravenous monotherapy using K202.B exhibited potent neutralizing activity in SARS-CoV-2 wild-type- and B.1.617.2 variant-infected mouse models, without significant toxicity in vivo. The results indicate that this novel approach of development of immunoglobulin G4-based bispecific antibody from an established human recombinant antibody library is likely to be an effective strategy for the rapid development of bispecific antibodies, and timely management against fast-evolving SARS-CoV-2 variants. •Development of novel engineered IgG4-[scFv]2 form of human bsAbs to SARS-CoV-2 RBD.•K202.B shows therapeutic potential against a variety of SARS-CoV-2 variants.•Cryo-EM-based structural analyses provide the action mechanism of K202.B.•Fast development of phage display-derived bsAb selection effective against COVID-19.