Recombinant Fc-fusion vaccine of RBD induced protection against SARS-CoV-2 in non-human primate and mice

Sun, Shihui; He, Lei; Zhao, Zhongpeng; Gu, Hongjing; Fang, Xin; Wang, Tiecheng; Yang, Xiaolan; Chen, Shaolong; Deng, Yongqiang; Li, Jiangfan; Zhao, Jian; Li, Liang; Li, Xinwang; He, Peng; Li, Ge; Li, Hao; Zhao, Yuee; Gao, Chunrun; Lang, Xiaolin; Wang, Xin; Fei, Guoqiang; Li, Yan; Geng, Shusheng; Gao, Yuwei; Wei, Wenjin; Hu, Zhongyu; Han, Gencheng; Sun, Yansong

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to infect people globally. The increased COVID-19 cases and no licensed vaccines highlight the need to develop safe and effective vaccines against SARS-CoV-2 infection. Multiple vaccines candidates are under pre-clinical or clinical trails with different strengths and weaknesses. Here we developed a pilot scale production of a recombinant subunit vaccine (RBD-Fc Vacc) with the Receptor Binding Domain of SARS-CoV-2 S protein fused with the Fc domain of human IgG1. RBD-Fc Vacc induced SARS-CoV-2 specific neutralizing antibodies in non-human primates and human ACE2 transgenic mice. The antibodies induced in macaca fascicularis neutralized three divergent SARS-CoV2 strains, suggesting a broader neutralizing ability. Three times immunizations protected Macaca fascicularis (20ug or 40ug per dose) and mice (10ug or 20ug per dose) from SARS-CoV-2 infection respectively. These data support clinical development of SARS-CoV-2 vaccines for humans. RBD-Fc Vacc is currently being assessed in randomized controlled phase 1/II human clinical trails. Summary This study confirms protective efficacy of a SARS-CoV-2 RBD-Fc subunit vaccine.