Structures of Human Antibodies Bound to SARS-CoV-2 Spike Reveal Common Epitopes and Recurrent Features of Antibodies.

Neutralizing antibody responses to coronaviruses mainly target the receptor-binding domain (RBD) of the trimeric spike. Here, we characterized polyclonal immunoglobulin Gs (IgGs) and Fabs from COVID-19 convalescent individuals for recognition of coronavirus spikes. Plasma IgGs differed in their focus on RBD epitopes, recognition of alpha- and beta-coronaviruses, and contributions of avidity to increased binding/neutralization of IgGs over Fabs. Using electron microscopy, we examined specificities of polyclonal plasma Fabs, revealing recognition of both S1A and RBD epitopes on SARS-CoV-2 spike. Moreover, a 3.4 Å cryo-electron microscopy (cryo-EM) structure of a neutralizing monoclonal Fab-spike complex revealed an epitope that blocks ACE2 receptor binding. Modeling based on these structures suggested different potentials for inter-spike crosslinking by IgGs on viruses, and characterized IgGs would not be affected by identified SARS-CoV-2 spike mutations. Overall, our studies structurally define a recurrent anti-SARS-CoV-2 antibody class derived from VH3-53/VH3-66 and similarity to a SARS-CoV VH3-30 antibody, providing criteria for evaluating vaccine-elicited antibodies.

Barnes CO ，West AP Jr ，Huey-Tubman KE ，Hoffmann MAG ，Sharaf NG ，Hoffman PR ，Koranda N ，Gristick HB ，Gaebler C ，Muecksch F ，Lorenzi JCC ，Finkin S ，Hägglöf T ，Hurley A ，Millard KG ，Weisblum Y ，Schmidt F ，Hatziioannou T ，Bieniasz PD ，Caskey M ，Robbiani DF ，Nussenzweig MC ，Bjorkman PJ ... -  《-》

Isolation of potent SARS-CoV-2 neutralizing antibodies and protection from disease in a small animal model.

Countermeasures to prevent and treat coronavirus disease 2019 (COVID-19) are a global health priority. We enrolled a cohort of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-recovered participants, developed neutralization assays to investigate antibody responses, adapted our high-throughput antibody generation pipeline to rapidly screen more than 1800 antibodies, and established an animal model to test protection. We isolated potent neutralizing antibodies (nAbs) to two epitopes on the receptor binding domain (RBD) and to distinct non-RBD epitopes on the spike (S) protein. As indicated by maintained weight and low lung viral titers in treated animals, the passive transfer of a nAb provides protection against disease in high-dose SARS-CoV-2 challenge in Syrian hamsters. The study suggests a role for nAbs in prophylaxis, and potentially therapy, of COVID-19. The nAbs also define protective epitopes to guide vaccine design.

Rogers TF ，Zhao F ，Huang D ，Beutler N ，Burns A ，He WT ，Limbo O ，Smith C ，Song G ，Woehl J ，Yang L ，Abbott RK ，Callaghan S ，Garcia E ，Hurtado J ，Parren M ，Peng L ，Ramirez S ，Ricketts J ，Ricciardi MJ ，Rawlings SA ，Wu NC ，Yuan M ，Smith DM ，Nemazee D ，Teijaro JR ，Voss JE ，Wilson IA ，Andrabi R ，Briney B ，Landais E ，Sok D ，Jardine JG ，Burton DR ... -  《-》

Exploring distinct modes of inter-spike cross-linking for enhanced neutralization by SARS-CoV-2 antibodies.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its Omicron subvariants drastically amplifies transmissibility, infectivity, and immune escape, mainly due to their resistance to most neutralizing antibodies. Thus, exploring the mechanisms underlying antibody evasion is crucial. Although the full-length native form of antibody, immunoglobulin G (IgG), offers valuable insights into the neutralization, structural investigations primarily focus on the fragment of antigen-binding (Fab). Here, we employ single-particle cryo-electron microscopy (cryo-EM) to characterize a W328-6H2 antibody, in its native IgG form complexed with severe acute respiratory syndrome (SARS), severe acute respiratory syndrome coronavirus 2 wild-type (WT) and Omicron variant BA.1 spike protein (S). Three high-resolution structures reveal that the full-length IgG forms a centered head-to-head dimer of trimer when binds fully stoichiometrically with both SARS and WT S, while adopting a distinct offset configuration with Omicron BA.1 S. Combined with functional assays, our results suggest that, beyond the binding affinity between the RBD epitope and Fab, the higher-order architectures of S trimer and full-length IgG play an additional role in neutralization, enriching our understanding of enhanced neutralization by SARS-CoV-2 antibodies.

Nan X ，Li Y ，Zhang R ，Wang R ，Lv N ，Li J ，Chen Y ，Zhou B ，Wang Y ，Wang Z ，Zhu J ，Chen J ，Li J ，Chen W ，Zhang Q ，Shi X ，Zhao C ，Chen C ，Liu Z ，Zhao Y ，Liu D ，Wang X ，Yan LT ，Li T ，Zhang L ，Yang YR ... -  《Nature Communications》

Potent neutralizing antibodies from COVID-19 patients define multiple targets of vulnerability.

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a large impact on global health, travel, and economy. Therefore, preventative and therapeutic measures are urgently needed. Here, we isolated monoclonal antibodies from three convalescent coronavirus disease 2019 (COVID-19) patients using a SARS-CoV-2 stabilized prefusion spike protein. These antibodies had low levels of somatic hypermutation and showed a strong enrichment in VH1-69, VH3-30-3, and VH1-24 gene usage. A subset of the antibodies was able to potently inhibit authentic SARS-CoV-2 infection at a concentration as low as 0.007 micrograms per milliliter. Competition and electron microscopy studies illustrate that the SARS-CoV-2 spike protein contains multiple distinct antigenic sites, including several receptor-binding domain (RBD) epitopes as well as non-RBD epitopes. In addition to providing guidance for vaccine design, the antibodies described here are promising candidates for COVID-19 treatment and prevention.

Brouwer PJM ，Caniels TG ，van der Straten K ，Snitselaar JL ，Aldon Y ，Bangaru S ，Torres JL ，Okba NMA ，Claireaux M ，Kerster G ，Bentlage AEH ，van Haaren MM ，Guerra D ，Burger JA ，Schermer EE ，Verheul KD ，van der Velde N ，van der Kooi A ，van Schooten J ，van Breemen MJ ，Bijl TPL ，Sliepen K ，Aartse A ，Derking R ，Bontjer I ，Kootstra NA ，Wiersinga WJ ，Vidarsson G ，Haagmans BL ，Ward AB ，de Bree GJ ，Sanders RW ，van Gils MJ ... -  《-》

Cross-Neutralization of a SARS-CoV-2 Antibody to a Functionally Conserved Site Is Mediated by Avidity.

Most antibodies isolated from individuals with coronavirus disease 2019 (COVID-19) are specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, COVA1-16 is a relatively rare antibody that also cross-neutralizes SARS-CoV. Here, we determined a crystal structure of the COVA1-16 antibody fragment (Fab) with the SARS-CoV-2 receptor-binding domain (RBD) and negative-stain electron microscopy reconstructions with the spike glycoprotein trimer to elucidate the structural basis of its cross-reactivity. COVA1-16 binds a highly conserved epitope on the SARS-CoV-2 RBD, mainly through a long complementarity-determining region (CDR) H3, and competes with the angiotensin-converting enzyme 2 (ACE2) receptor because of steric hindrance rather than epitope overlap. COVA1-16 binds to a flexible up conformation of the RBD on the spike and relies on antibody avidity for neutralization. These findings, along with the structural and functional rationale for epitope conservation, provide insights for development of more universal SARS-like coronavirus vaccines and therapies.

Liu H ，Wu NC ，Yuan M ，Bangaru S ，Torres JL ，Caniels TG ，van Schooten J ，Zhu X ，Lee CD ，Brouwer PJM ，van Gils MJ ，Sanders RW ，Ward AB ，Wilson IA ... -  《-》