Reduced binding activity of vaccine serum to omicron receptor-binding domain

• Published in: Frontiers in immunology Vol. 13; p. 960195
• Main Authors: Li, Mingzhi, Weng, Shiqi, Wang, Quansheng, Yang, Zibing, Wang, Xiaoling, Yin, Yanjun, Zhou, Qiuxiang, Zhang, Lirong, Tao, Feifei, Li, Yihan, Jia, Mengle, Yang, Lingdi, Xin, Xiu, Li, Hanguang, Kang, Lumei, Wang, Yu, Wang, Ting, Li, Sha, Kong, Lingbao
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 28.07.2022
• Subjects: binding activity; COVID-19; Immunology; omicron; RBD; spike protein
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.960195

Coronavirus disease 2019 (COVID-19) vaccination regimens contribute to limiting the spread of severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2). However, the emergence and rapid transmission of the SARS-CoV-2 variant Omicron raise a concern about the efficacy of the current vaccination strategy. Here, we expressed monomeric and dimeric receptor-binding domains (RBDs) of the spike protein of prototype SARS-CoV-2 and Omicron variant in E. coli and investigated the reactivity of anti-sera from Chinese subjects immunized with SARS-CoV-2 vaccines to these recombinant RBDs. In 106 human blood samples collected from 91 participants from Jiangxi, China, 26 sera were identified to be positive for SARS-CoV-2 spike protein antibodies by lateral flow dipstick (LFD) assays, which were enriched in the ones collected from day 7 to 1 month post-boost (87.0%) compared to those harvested within 1 week post-boost (23.8%) ( P < 0.0001). A higher positive ratio was observed in the child group (40.8%) than adults (13.6%) ( P = 0.0073). ELISA results showed that the binding activity of anti-SARS-CoV-2 antibody-positive sera to Omicron RBDs dropped by 1.48- to 2.07-fold compared to its homogeneous recombinant RBDs. Thus, our data indicate that current SARS-CoV-2 vaccines provide restricted humoral protection against the Omicron variant.