A potent SARS-CoV-2 antibody neutralizes Omicron variant by disassembling the spike trimer

The continuous emergence of novel SARS-CoV-2 variants poses new challenges to the fight against the COVID-19 pandemic. The newly emerging Omicron strain caused serious immune escape and raised unprecedented concern all over the world. The development of antibody targeting conserved and universal epitope is urgently needed. A subset neutralizing antibody(nAbs) against COVID-19 from convalescent patients were isolated in our previous study. Here in this study, we investigated the accommodation of these nAbs to SARS-CoV-2 variants of concerns (VOCs), revealing that IgG 553-49 neutralizes pseudovirus of SARS-CoV-2 Omicron variant. In addition, we determined the cryo-EM structure of SARS-CoV-2 spike complexed with three antibodies targeting different epitopes, including 553-49, 553-15 and 553-60. Notably, 553-49 targets a novel conserved epitope and neutralizes virus by disassembling spike trimers. 553-15, an antibody that neutralizes all the other VOCs except omicron, cross-links two spike trimers to form trimer dimer, demonstrating that 553-15 neutralizes virus by steric hindrance and virion aggregation. These findings suggest the potential to develop 49 and other antibody targeting this highly conserved epitope as promising cocktail therapeutics reagent for COVID-19. ImportanceThe newly emergence of Omicron strain caused higher immune escape, raising unprecedented concerns about the effectiveness of antibody therapies and vaccines. In this study, we identified a SARS-CoV-2 Omicron neutralizing antibody 553-49, which neutralizes Omicron variant by targeting a completely conserved novel epitope. Besides, we revealed that IgG 553-15 neutralizes SARS-CoV-2 by crosslinking virions and 553-60 functions by blocking receptor binding. Comparison of different RBD epitopes revealed that the epitope of 553-49 is hidden in the S trimer and keeps high conservation during SARS-CoV-2 evolution, making 553-49 a promising therapeutics reagent to fight against the emerging Omicron and future variant of SARS-CoV-2.