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1.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-295926

ABSTRACT

We have identified camelid single-domain antibodies (VHHs) that cross-neutralize SARS-CoV-1 and −2, such as VHH72, which binds to a unique highly conserved epitope in the viral receptor-binding domain (RBD) that is difficult to access for human antibodies. Here, we establish a protein engineering path for how a stable, long-acting drug candidate can be generated out of such a VHH building block. When fused to human IgG1-Fc, the prototype VHH72 molecule prophylactically protects hamsters from SARS-CoV-2. In addition, we demonstrate that both systemic and intranasal application protects hACE-2-transgenic mice from SARS-CoV-2 induced lethal disease progression. To boost potency of the lead, we used structure-guided molecular modeling combined with rapid yeast-based Fc-fusion prototyping, resulting in the affinity-matured VHH72_S56A-Fc, with subnanomolar SARS-CoV-1 and −2 neutralizing potency. Upon humanization, VHH72_S56A was fused to a human IgG1 Fc with optimized manufacturing homogeneity and silenced effector functions for enhanced safety, and its stability as well as lack of off-target binding was extensively characterized. Therapeutic systemic administration of a low dose of VHH72_S56A-Fc antibodies strongly restricted replication of both original and D614G mutant variants of SARS-CoV-2 virus in hamsters, and minimized the development of lung damage. This work led to the selection of XVR011 for clinical development, a highly stable anti-COVID-19 biologic with excellent manufacturability. Additionally, we show that XVR011 is unaffected in its neutralizing capacity of currently rapidly spreading SARS-CoV-2 variants, and demonstrate its unique, wide scope of binding across the Sarbecovirus clades.

2.
Sci Transl Med ; 13(621): eabi7826, 2021 Nov 24.
Article in English | MEDLINE | ID: covidwho-1450584

ABSTRACT

Broadly neutralizing antibodies are an important treatment for individuals with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Antibody-based therapeutics are also essential for pandemic preparedness against future Sarbecovirus outbreaks. Camelid-derived single domain antibodies (VHHs) exhibit potent antimicrobial activity and are being developed as SARS-CoV-2­neutralizing antibody-like therapeutics. Here, we identified VHHs that neutralize both SARS-CoV-1 and SARS-CoV-2, including now circulating variants. We observed that the VHHs bound to a highly conserved epitope in the receptor binding domain of the viral spike protein that is difficult to access for human antibodies. Structure-guided molecular modeling, combined with rapid yeast-based prototyping, resulted in an affinity enhanced VHH-human immunoglobulin G1 Fc fusion molecule with subnanomolar neutralizing activity. This VHH-Fc fusion protein, produced in and purified from cultured Chinese hamster ovary cells, controlled SARS-CoV-2 replication in prophylactic and therapeutic settings in mice expressing human angiotensin converting enzyme 2 and in hamsters infected with SARS-CoV-2. These data led to affinity-enhanced selection of the VHH, XVR011, a stable anti­COVID-19 biologic that is now being evaluated in the clinic.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Animals , Antibodies, Neutralizing , Antibodies, Viral , Humans , Models, Animal , SARS-CoV-2
4.
Science ; 371(6530): 681-682, 2021 02 12.
Article in English | MEDLINE | ID: covidwho-1091001
5.
Nat Commun ; 11(1): 5838, 2020 11 17.
Article in English | MEDLINE | ID: covidwho-933686

ABSTRACT

Emergence of SARS-CoV-2 causing COVID-19 has resulted in hundreds of thousands of deaths. In search for key targets of effective therapeutics, robust animal models mimicking COVID-19 in humans are urgently needed. Here, we show that Syrian hamsters, in contrast to mice, are highly permissive to SARS-CoV-2 and develop bronchopneumonia and strong inflammatory responses in the lungs with neutrophil infiltration and edema, further confirmed as consolidations visualized by micro-CT alike in clinical practice. Moreover, we identify an exuberant innate immune response as key player in pathogenesis, in which STAT2 signaling plays a dual role, driving severe lung injury on the one hand, yet restricting systemic virus dissemination on the other. Our results reveal the importance of STAT2-dependent interferon responses in the pathogenesis and virus control during SARS-CoV-2 infection and may help rationalizing new strategies for the treatment of COVID-19 patients.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/pathology , Coronavirus Infections/virology , Disease Models, Animal , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , STAT2 Transcription Factor/metabolism , Signal Transduction , Animals , Betacoronavirus/pathogenicity , COVID-19 , Coronavirus Infections/immunology , Coronavirus Infections/metabolism , Cricetinae , Immunity, Innate , Interferon Type I/genetics , Interferon Type I/metabolism , Lung/pathology , Lung/virology , Mice , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/metabolism , SARS-CoV-2 , STAT2 Transcription Factor/genetics , Virus Replication
6.
Cell ; 181(5): 1004-1015.e15, 2020 05 28.
Article in English | MEDLINE | ID: covidwho-88549

ABSTRACT

Coronaviruses make use of a large envelope protein called spike (S) to engage host cell receptors and catalyze membrane fusion. Because of the vital role that these S proteins play, they represent a vulnerable target for the development of therapeutics. Here, we describe the isolation of single-domain antibodies (VHHs) from a llama immunized with prefusion-stabilized coronavirus spikes. These VHHs neutralize MERS-CoV or SARS-CoV-1 S pseudotyped viruses, respectively. Crystal structures of these VHHs bound to their respective viral targets reveal two distinct epitopes, but both VHHs interfere with receptor binding. We also show cross-reactivity between the SARS-CoV-1 S-directed VHH and SARS-CoV-2 S and demonstrate that this cross-reactive VHH neutralizes SARS-CoV-2 S pseudotyped viruses as a bivalent human IgG Fc-fusion. These data provide a molecular basis for the neutralization of pathogenic betacoronaviruses by VHHs and suggest that these molecules may serve as useful therapeutics during coronavirus outbreaks.


Subject(s)
Antibodies, Neutralizing/isolation & purification , Betacoronavirus/immunology , Single-Domain Antibodies/isolation & purification , Animals , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/immunology , COVID-19 , Camelids, New World/immunology , Coronavirus Infections/therapy , Cross Reactions , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Models, Molecular , Pandemics , Pneumonia, Viral/therapy , Protein Domains , Receptors, Virus/chemistry , SARS-CoV-2 , Single-Domain Antibodies/chemistry , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology
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