RBD class 1 and 2 antibody epitopes elicit around 70% neutralizing capacity against SARS-CoV-2 virus following boosting with inactivated virus vaccine

• Published in: Vaccine Vol. 41; no. 52; pp. 7641 - 7646
• Main Authors: Wang, Yuanyuan, Hu, Yunqi, Ma, Yong, Li, Pengbin, Zhou, Siwei, Xu, Mengxin, He, Bing, Liu, Shuning, Lv, Kexin, Liu, Sizhe, Zhang, Yu, Zhou, Na, Chen, Shifeng, Ye, Feng, Chen, Yao-Qing
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 18.12.2023; Elsevier Limited
• Subjects: Allergy and Immunology; Antibodies; Antibodies, Blocking; Antibodies, Neutralizing; Antibodies, Viral; Cell culture; class; COVID-19; COVID-19 - prevention & control; COVID-19 infection; COVID-19 Vaccines; Deactivation; Depletion; Enzymes; Epitopes; Humans; Inactivated SARS-CoV-2 vaccine; Life sciences; Neutralizing; Neutralizing antibodies; Neutralizing capacity; Pandemics; Plasma; Plasmids; Proteins; Public health; RBD epitopes; Regression analysis; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Software; Statistical analysis; Vaccines; Vaccines, Inactivated; Viral infections; Viruses; Beijing China; China; RBD epitopes; SARS-CoV-2; Neutralizing capacity; Inactivated SARS-CoV-2 vaccine; Neutralizing antibodies
• ISSN: 0264-410X; 1873-2518; 1873-2518
• DOI: 10.1016/j.vaccine.2023.11.037

A third dose of inactivated virus vaccine (IVV) boosts neutralizing antibodies, reducing SARS-CoV-2 transmission rate and COVID-19 severity. However, the impact of RBD-elicited antibodies and their neutralizing activity by the boost of IVV is unknown. We investigated the impact of IVV's boost shot on RBD-elicited antibodies and their neutralizing activity in 18 subjects receiving the second and third IVV doses. Using an RBD antibodies depletion assay, we assessed the neutralizing activity of RBD-elicited antibodies. After the second dose, RBD-antigen elicitation accounted for ∼60% of neutralizing activity, which increased to 82% after the IVV boost against ancestral SARS-CoV-2. Depleting class 3 and class 4-specific antibodies with the Beta-RBD protein revealed that NAbs targeting RBD class 1 and class 2 subdomains increased from 57% to 75% post-boost. These findings highlight the significant enhancement of RBD-specific antibodies, especially against RBD class 1 and class 2, with IVV booster doses. Our study offers valuable insights for optimizing COVID-19 vaccine strategies.