http://www.cell.com/article/S0092867422000770/pdf

Structural and functional characterizations of infectivity and immune evasion of SARS-CoV-2 Omicron

Omicron (B.1.1.529), the most heavily mutated SARS-CoV-2 variant so far, is highly resistant to neutralizing antibodies, raising concerns about the effectiveness of antibody therapies and vaccines1,2. Here we examined whether sera from individuals who received two or three doses of inactivated SARS-CoV-2 vaccine could neutralize authentic Omicron. The seroconversion rates of neutralizing antibodies were 3.3% (2 out of 60) and 95% (57 out of 60) for individuals who had received 2 and 3 doses of vaccine, respectively. For recipients of three vaccine doses, the geometric mean neutralization antibody titre for Omicron was 16.5-fold lower than for the ancestral virus (254). We isolated 323 human monoclonal antibodies derived from memory B cells in triple vaccinees, half of which recognized the receptor-binding domain, and showed that a subset (24 out of 163) potently neutralized all SARS-CoV-2 variants of concern, including Omicron. Therapeutic treatments with representative broadly neutralizing monoclonal antibodies were highly protective against infection of mice with SARS-CoV-2 Beta (B.1.351) and Omicron. Atomic structures of the Omicron spike protein in complex with three classes of antibodies that were active against all five variants of concern defined the binding and neutralizing determinants and revealed a key antibody escape site, G446S, that confers greater resistance to a class of antibodies that bind on the right shoulder of the receptor-binding domain by altering local conformation at the binding interface. Our results rationalize the use of three-dose immunization regimens and suggest that the fundamental epitopes revealed by these broadly ultrapotent antibodies are rational targets for a universal sarbecovirus vaccine. 

/pdf/memory-b-cell-repertoire-from-triple-vaccinees-against-lypmfchu.pdf

Memory B cell repertoire from triple vaccinees against diverse SARS-CoV-2 variants

/pdf/memory-b-cell-repertoire-from-triple-vaccinees-against-1eg3tfzb.pdf

The coronavirus disease 2019 (COVID-19) pandemic is an exceptional public health crisis that demands the timely creation of new therapeutics and viral detection. Owing to their high specificity and reliability, monoclonal antibodies (mAbs) have emerged as powerful tools to treat and detect numerous diseases. Hence, many researchers have begun to urgently develop Ab-based kits for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Ab drugs for use as COVID-19 therapeutic agents. The detailed structure of the SARS-CoV-2 spike protein is known, and since this protein is key for viral infection, its receptor-binding domain (RBD) has become a major target for therapeutic Ab development. Because SARS-CoV-2 is an RNA virus with a high mutation rate, especially under the selective pressure of aggressively deployed prophylactic vaccines and neutralizing Abs, the use of Ab cocktails is expected to be an important strategy for effective COVID-19 treatment. Moreover, SARS-CoV-2 infection may stimulate an overactive immune response, resulting in a cytokine storm that drives severe disease progression. Abs to combat cytokine storms have also been under intense development as treatments for COVID-19. In addition to their use as drugs, Abs are currently being utilized in SARS-CoV-2 detection tests, including antigen and immunoglobulin tests. Such Ab-based detection tests are crucial surveillance tools that can be used to prevent the spread of COVID-19. Herein, we highlight some key points regarding mAb-based detection tests and treatments for the COVID-19 pandemic. 

/pdf/monoclonal-antibodies-for-covid-19-therapy-and-sars-cov-2-16gddpo4.pdf

Monoclonal antibodies for COVID-19 therapy and SARS-CoV-2 detection

/pdf/monoclonal-antibodies-for-covid-19-therapy-and-sars-cov-2-28nps2sq.pdf

Receptor recognition and subsequent membrane fusion are essential for the establishment of successful infection by SARS-CoV-2. Halting these steps can cure COVID-19. Here we have identified and characterized a potent human monoclonal antibody, HB27, that blocks SARS-CoV-2 attachment to its cellular receptor at sub-nM concentrations. Remarkably, HB27 can also prevent SARS-CoV-2 membrane fusion. Consequently, a single dose of HB27 conferred effective protection against SARS-CoV-2 in two established mouse models. Rhesus macaques showed no obvious adverse events when administrated with 10 times the effective dose of HB27. Cryo-EM studies on complex of SARS-CoV-2 trimeric S with HB27 Fab reveal that three Fab fragments work synergistically to occlude SARS-CoV-2 from binding to the ACE2 receptor. Binding of the antibody also restrains any further conformational changes of the receptor binding domain, possibly interfering with progression from the prefusion to the postfusion stage. These results suggest that HB27 is a promising candidate for immuno-therapies against COVID-19.

/pdf/double-lock-of-a-potent-human-therapeutic-monoclonal-36shu5vfxw.pdf

Double lock of a potent human therapeutic monoclonal antibody against SARS-CoV-2.

Summary Receptor recognition and subsequent membrane fusion are essential for the establishment of successful infection by SARS-CoV-2. Halting these steps can cure COVID-19. Here we have identified and characterized a potent human monoclonal antibody, HB27, that blocks SARS-CoV-2 attachment to its cellular receptor at sub-nM concentrations. Remarkably, HB27 can also prevent SARS-CoV-2 membrane fusion. Consequently, a single dose of HB27 conferred effective protection against SARS-CoV-2 in two established mouse models. Rhesus macaques showed no obvious adverse events when administrated with 10-fold of effective dose of HB27. Cryo-EM studies on complex of SARS-CoV-2 trimeric S with HB27 Fab reveal that three Fab fragments work synergistically to occlude SARS-CoV-2 from binding to ACE2 receptor. Binding of the antibody also restrains any further conformational changes of the RBD, possibly interfering with progression from the prefusion to the postfusion stage. These results suggest that HB27 is a promising candidate for immuno-therapies against COVID-19. Highlights SARS-CoV-2 specific antibody, HB27, blocks viral receptor binding and membrane fusion HB27 confers prophylactic and therapeutic protection against SARS-CoV-2 in mice models Rhesus macaques showed no adverse side effects when administered with HB27 Cryo-EM studies suggest that HB27 sterically occludes SARS-CoV-2 from its receptor

https://biorxiv.org/content/10.1101/2020.11.24.393629v1.full.pdf

Double Lock of a Potent Human Monoclonal Antibody against SARS-CoV-2

Vascular endothelial growth factor receptor 2 (VEGFR2)/KDR plays a critical role in tumor growth, diffusion, and invasion. The amino acid sequence homology of KDR between mouse and human in the VEGF ligand‐binding domain was low, thus the WT mice could not be used to evaluate Abs against human KDR, and the lack of a suitable mouse model hindered both basic research and drug developments. Using the CRISPR/Cas9 technique, we successfully inserted different fragments of the human KDR coding sequence into the chromosomal mouse Kdr exon 4 locus to obtain an hKDR humanized mouse that can be used to evaluate the marketed Ab ramucirumab. In addition, the humanized mAb VEGFR‐HK19 was developed, and a series of comparative assays with ramucirumab as the benchmark revealed that VEGFR‐HK19 has higher affinity and superior antiproliferation activity. Moreover, VEGFR‐HK19 selectively inhibited tumor growth in the hKDR mouse model but not in WT mice. The most important binding epitopes of VEGFR2‐HK19 are D257, L313, and T315, located in the VEGF binding region. Therefore, the VEGFR2‐HK19 Ab inhibits tumor growth by blocking VEGF‐induced angiogenesis, inflammation, and promoting apoptosis. To our best knowledge, this novel humanized KDR mouse fills the gaps both in an animal model and the suitable in vivo evaluation method for developing antiangiogenesis therapies in the future, and the newly established humanized Ab is expected to be a drug candidate possibly benefitting tumor patients.

Novel hKDR mouse model depicts the antiangiogenesis and apoptosis‐promoting effects of neutralizing antibodies targeting vascular endothelial growth factor receptor 2

/pdf/mutation-n856k-in-spike-reduces-fusogenicity-and-infectivity-1waeq22o.pdf

Huiyu Wang

Papers

Double lock of a potent human therapeutic monoclonal antibody against SARS-CoV-2.

Double Lock of a Potent Human Monoclonal Antibody against SARS-CoV-2

Novel hKDR mouse model depicts the antiangiogenesis and apoptosis‐promoting effects of neutralizing antibodies targeting vascular endothelial growth factor receptor 2

Mutation N856K in spike reduces fusogenicity and infectivity of Omicron BA.1