Abstract
Within a year after its emergence, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 100 million people worldwide with a death toll over 2 million. Vaccination remains the best hope to ultimately put this pandemic to an end. Here, using Trimer-Tag technology, we produced both wild-type (WT) and furin site mutant (MT) S-Trimers for COVID-19 vaccine studies. Cryo-EM structures of the WT and MT S-Trimers, determined at 3.2 Å and 2.6 Å respectively, revealed that both antigens adopt a tightly closed conformation and their structures are essentially identical to that of the previously solved full-length WT S protein in detergent. The tightly closed conformation is stabilized by fatty acid and polysorbate 80 binding at the receptor binding domains (RBDs) and the N terminal domains (NTDs) respectively. Additionally, we identified an important pH switch in the WT S-Trimer that shows dramatic conformational change and accounts for its increased stability at lower pH. These results validate Trimer-Tag as a platform technology in production of metastable WT S-Trimer as a candidate for COVID-19 subunit vaccine. IMPORTANCE Effective vaccine against SARS-CoV-2 is critical to end the COVID-19 pandemic. Here, using Trimer-Tag technology, we are able to produce stable and large quantities of WT S-Trimer, a subunit vaccine candidate for COVID-19 with high safety and efficacy from animal and Phase 1 clinical trial studies. Cryo-EM structures of the S-Trimer subunit vaccine candidate show that it predominately adopts tightly closed pre-fusion state, and resembles that of the native and full-length spike in detergent, confirming its structural integrity. WT S-Trimer is currently being evaluated in global Phase 2/3 clinical trial. Combining with published structures of the S protein, we also propose a model to dissect the conformation change of the spike protein before receptor binding.
【저자키워드】 breath, 【초록키워드】 COVID-19, Structure, SARS-CoV-2, Efficacy, Vaccine, coronavirus, COVID-19 vaccine, clinical trial, pandemic, S protein, furin, COVID-19 pandemic, severe acute respiratory syndrome Coronavirus, Spike protein, Receptor binding domain, Antigen, Protein, stability, death, vaccine candidate, antigens, Subunit vaccine, mutant, Critical, platform, Fatty acid, cryo-EM structures, binding, N terminal domain, Polysorbate, Receptor binding, conformational change, RBDs, phase, Phase 1, acute respiratory syndrome, polysorbate 80, subunit, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, furin site, candidate, wild-type, NTDs, full-length, cryo, receptor binding domains, detergent, pre-fusion, Trimers, WT S, produced, evaluated, the spike protein, the S protein, dissect, fatty, 【제목키워드】 COVID-19, vaccine candidate, subunit,