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1.
Euro Surveill ; 25(28)2020 07.
Article in English | MEDLINE | ID: covidwho-647504

ABSTRACT

BackgroundA novel coronavirus, SARS-CoV-2, which emerged at the end of 2019 and causes COVID-19, has resulted in worldwide human infections. While genetically distinct, SARS-CoV-1, the aetiological agent responsible for an outbreak of severe acute respiratory syndrome (SARS) in 2002-2003, utilises the same host cell receptor as SARS-CoV-2 for entry: angiotensin-converting enzyme 2 (ACE2). Parts of the SARS-CoV-1 spike glycoprotein (S protein), which interacts with ACE2, appear conserved in SARS-CoV-2.AimThe cross-reactivity with SARS-CoV-2 of monoclonal antibodies (mAbs) previously generated against the S protein of SARS-CoV-1 was assessed.MethodsThe SARS-CoV-2 S protein sequence was aligned to those of SARS-CoV-1, Middle East respiratory syndrome (MERS) and common-cold coronaviruses. Abilities of mAbs generated against SARS-CoV-1 S protein to bind SARS-CoV-2 or its S protein were tested with SARS-CoV-2 infected cells as well as cells expressing either the full length protein or a fragment of its S2 subunit. Quantitative ELISA was also performed to compare binding of mAbs to recombinant S protein.ResultsAn immunogenic domain in the S2 subunit of SARS-CoV-1 S protein is highly conserved in SARS-CoV-2 but not in MERS and human common-cold coronaviruses. Four murine mAbs raised against this immunogenic fragment could recognise SARS-CoV-2 S protein expressed in mammalian cell lines. In particular, mAb 1A9 was demonstrated to detect S protein in SARS-CoV-2-infected cells and is suitable for use in a sandwich ELISA format.ConclusionThe cross-reactive mAbs may serve as useful tools for SARS-CoV-2 research and for the development of diagnostic assays for COVID-19.


Subject(s)
Antibodies, Monoclonal/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , SARS Virus/immunology , Severe Acute Respiratory Syndrome/immunology , Spike Glycoprotein, Coronavirus/immunology , Amino Acid Sequence , Animals , Betacoronavirus/genetics , Blotting, Western , COS Cells , Chlorocebus aethiops , Conserved Sequence , Coronavirus Infections/genetics , Coronavirus Infections/virology , Cross Reactions/immunology , Enzyme-Linked Immunosorbent Assay/methods , Fluorescent Antibody Technique/methods , Genome, Viral , Mice , Pandemics , Peptidyl-Dipeptidase A/immunology , Plasmids , Pneumonia, Viral/genetics , Recombinant Proteins/immunology , SARS Virus/genetics , Sequence Alignment , Severe Acute Respiratory Syndrome/virology , Spike Glycoprotein, Coronavirus/genetics , Transfection , Vero Cells , Virus Integration
2.
Int Immunopharmacol ; 86: 106760, 2020 Sep.
Article in English | MEDLINE | ID: covidwho-634138

ABSTRACT

Due to the vastness of the science virology, it is no longer an offshoot solely of the microbiology. Viruses have become as the causative agents of major epidemics throughout history. Many therapeutic strategies have been used for these microorganisms, and in this way the recognizing of potential targets of viruses is of particular importance for success. For decades, antibodies and antibody fragments have occupied a significant body of the treatment approaches against infectious diseases. Because of their high affinity, they can be designed and engineered against a variety of purposes, mainly since antibody fragments such as scFv, nanobody, diabody, and bispecific antibody have emerged owing to their small size and interesting properties. In this review, we have discussed the antibody discovery and molecular and biological design of antibody fragments as inspiring therapeutic and diagnostic agents against viral targets.


Subject(s)
Antibodies, Viral/therapeutic use , Betacoronavirus/immunology , Biological Products/therapeutic use , Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Animals , Antibodies, Bispecific/immunology , Antibodies, Bispecific/therapeutic use , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/therapeutic use , Antibodies, Viral/immunology , Biological Products/immunology , Coronavirus Infections/epidemiology , Coronavirus Infections/immunology , Coronavirus Infections/virology , Disease Models, Animal , Drug Design , Drug Discovery , Humans , Pandemics , Pneumonia, Viral/epidemiology , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , Single-Domain Antibodies/immunology , Single-Domain Antibodies/therapeutic use
3.
Nat Commun ; 11(1): 4303, 2020 08 27.
Article in English | MEDLINE | ID: covidwho-733523

ABSTRACT

The novel highly transmissible human coronavirus SARS-CoV-2 is the causative agent of the COVID-19 pandemic. Thus far, there is no approved therapeutic drug specifically targeting this emerging virus. Here we report the isolation and characterization of a panel of human neutralizing monoclonal antibodies targeting the SARS-CoV-2 receptor binding domain (RBD). These antibodies were selected from a phage display library constructed using peripheral circulatory lymphocytes collected from patients at the acute phase of the disease. These neutralizing antibodies are shown to recognize distinct epitopes on the viral spike RBD. A subset of the antibodies exert their inhibitory activity by abrogating binding of the RBD to the human ACE2 receptor. The human monoclonal antibodies described here represent a promising basis for the design of efficient combined post-exposure therapy for SARS-CoV-2 infection.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Antibodies, Viral/immunology , Antibodies, Viral/metabolism , Betacoronavirus/metabolism , Chlorocebus aethiops , Epitope Mapping , Epitopes , Humans , Peptide Library , Peptidyl-Dipeptidase A/metabolism , Protein Binding , Protein Interaction Domains and Motifs , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
4.
Biosensors (Basel) ; 10(9)2020 Aug 24.
Article in English | MEDLINE | ID: covidwho-727396

ABSTRACT

Cytokines are a family of proteins which play a major role in the regulation of the immune system and the development of several diseases, from rheumatoid arthritis to cancer and, more recently, COVID-19. Therefore, many efforts are currently being developed to improve therapy and diagnosis, as well as to produce inhibitory drugs and biosensors for a rapid, minimally invasive, and effective detection. In this regard, even more efficient cytokine receptors are under investigation. In this paper we analyze a set of IL-6 cytokine receptors, investigating their topological features by means of a theoretical approach. Our results suggest a topological indicator that may help in the identification of those receptors having the highest complementarity with the protein, a feature expected to ensure a stable binding. Furthermore, we propose and discuss the use of these receptors in an idealized experimental setup.


Subject(s)
Biosensing Techniques/methods , Interleukin-6/analysis , Receptors, Interleukin-6/analysis , Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal, Humanized/chemistry , Antibodies, Monoclonal, Humanized/immunology , Aptamers, Nucleotide/chemistry , Betacoronavirus/isolation & purification , Coronavirus Infections/diagnosis , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Humans , Immunoglobulin Fab Fragments/analysis , Immunoglobulin Fab Fragments/immunology , Interleukin-6/immunology , Limit of Detection , Pandemics , Pneumonia, Viral/diagnosis , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , Receptors, Interleukin-6/immunology
5.
Nat Commun ; 11(1): 4198, 2020 08 21.
Article in English | MEDLINE | ID: covidwho-724360

ABSTRACT

COVID-19 caused by SARS-CoV-2 has become a global pandemic requiring the development of interventions for the prevention or treatment to curtail mortality and morbidity. No vaccine to boost mucosal immunity, or as a therapeutic, has yet been developed to SARS-CoV-2. In this study, we discover and characterize a cross-reactive human IgA monoclonal antibody, MAb362. MAb362 binds to both SARS-CoV and SARS-CoV-2 spike proteins and competitively blocks ACE2 receptor binding, by overlapping the ACE2 structural binding epitope. Furthermore, MAb362 IgA neutralizes both pseudotyped SARS-CoV and SARS-CoV-2 in 293 cells expressing ACE2. When converted to secretory IgA, MAb326 also neutralizes authentic SARS-CoV-2 virus while the IgG isotype shows no neutralization. Our results suggest that SARS-CoV-2 specific IgA antibodies, such as MAb362, may provide effective immunity against SARS-CoV-2 by inducing mucosal immunity within the respiratory system, a potentially critical feature of an effective vaccine.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Immunoglobulin A/immunology , Peptidyl-Dipeptidase A/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Chlorocebus aethiops , Cross Reactions , Epitopes , HEK293 Cells , Humans , Immunoglobulin A/metabolism , Immunoglobulin A, Secretory/immunology , Immunoglobulin A, Secretory/metabolism , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Models, Molecular , Mutation , Protein Binding , Protein Interaction Domains and Motifs , SARS Virus/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
7.
J Exp Med ; 217(11)2020 11 02.
Article in English | MEDLINE | ID: covidwho-697830

ABSTRACT

The emergence of SARS-CoV-2 and the ensuing explosive epidemic of COVID-19 disease has generated a need for assays to rapidly and conveniently measure the antiviral activity of SARS-CoV-2-specific antibodies. Here, we describe a collection of approaches based on SARS-CoV-2 spike-pseudotyped, single-cycle, replication-defective human immunodeficiency virus type-1 (HIV-1), and vesicular stomatitis virus (VSV), as well as a replication-competent VSV/SARS-CoV-2 chimeric virus. While each surrogate virus exhibited subtle differences in the sensitivity with which neutralizing activity was detected, the neutralizing activity of both convalescent plasma and human monoclonal antibodies measured using each virus correlated quantitatively with neutralizing activity measured using an authentic SARS-CoV-2 neutralization assay. The assays described herein are adaptable to high throughput and are useful tools in the evaluation of serologic immunity conferred by vaccination or prior SARS-CoV-2 infection, as well as the potency of convalescent plasma or human monoclonal antibodies.


Subject(s)
Antibodies, Neutralizing/analysis , Antibodies, Viral/analysis , Betacoronavirus/immunology , Coronavirus Infections/immunology , Immunoassay/methods , Pneumonia, Viral/immunology , Animals , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Betacoronavirus/genetics , Cell Line , Chimera/genetics , Chimera/immunology , Chlorocebus aethiops , Coronavirus Infections/virology , HEK293 Cells , HIV-1/genetics , HIV-1/immunology , Humans , Neutralization Tests/methods , Pandemics , Pneumonia, Viral/virology , Recombination, Genetic , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vero Cells , Vesicular stomatitis Indiana virus/genetics , Vesicular stomatitis Indiana virus/immunology
8.
Monoclon Antib Immunodiagn Immunother ; 39(4): 107-111, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-696013

ABSTRACT

In this hypothesis, we address the biological/immunological pathway leading to severe disease or death after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying immune response is described with "original antigenic sin" (OAS) whereby previous infections influence the response to future virus encounters. We cite evidence for OAS-induced immunopathology in HIV-1 disease. We hypothesize that similar immune abnormalities can occur after infection with SARS-CoV-2. This hypothesis is supported by recent analysis of the antibodies in infected patients demonstrating serological and B cell abnormalities. The concept of symmetrical clonal regulation developed earlier for the immune network illustrates the pathway suggested by our hypothesis and may be helpful to develop strategies avoiding severe coronavirus disease 2019.


Subject(s)
Antibodies, Viral/immunology , B-Lymphocytes/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Immune Evasion/immunology , Pneumonia, Viral/immunology , Antibodies, Monoclonal/immunology , Coronavirus Infections/pathology , Cross Reactions/immunology , Cytokine Release Syndrome/immunology , HIV/immunology , HIV-1/immunology , Humans , Immunoglobulin G/immunology , Immunoglobulin M/immunology , Immunologic Memory/immunology , Pandemics , Pneumonia, Viral/pathology
9.
Immunol Cell Biol ; 98(4): 287-304, 2020 04.
Article in English | MEDLINE | ID: covidwho-685605

ABSTRACT

The human fragment crystallizable (Fc)γ receptor (R) interacts with antigen-complexed immunoglobulin (Ig)G ligands to both activate and modulate a powerful network of inflammatory host-protective effector functions that are key to the normal physiology of immune resistance to pathogens. More than 100 therapeutic monoclonal antibodies (mAbs) are approved or in late stage clinical trials, many of which harness the potent FcγR-mediated effector systems to varying degrees. This is most evident for antibodies targeting cancer cells inducing antibody-dependent killing or phagocytosis but is also true to some degree for the mAbs that neutralize or remove small macromolecules such as cytokines or other Igs. The use of mAb therapeutics has also revealed a "scaffolding" role for FcγR which, in different contexts, may either underpin the therapeutic mAb action such as immune agonism or trigger catastrophic adverse effects. The still unmet therapeutic need in many cancers, inflammatory diseases or emerging infections such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires increased effort on the development of improved and novel mAbs. A more mature appreciation of the immunobiology of individual FcγR function and the complexity of the relationships between FcγRs and antibodies is fueling efforts to develop more potent "next-gen" therapeutic antibodies. Such development strategies now include focused glycan or protein engineering of the Fc to increase affinity and/or tailor specificity for selective engagement of individual activating FcγRs or the inhibitory FcγRIIb or alternatively, for the ablation of FcγR interaction altogether. This review touches on recent aspects of FcγR and IgG immunobiology and its relationship with the present and future actions of therapeutic mAbs.


Subject(s)
Antibodies, Monoclonal , Immunotherapy , Receptors, IgG/immunology , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/therapeutic use , Antibody-Dependent Cell Cytotoxicity/immunology , Betacoronavirus/immunology , Coronavirus Infections/drug therapy , Coronavirus Infections/immunology , Coronavirus Infections/therapy , Humans , Neoplasms/immunology , Neoplasms/therapy , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/therapy
10.
Drug Des Devel Ther ; 14: 2607-2611, 2020.
Article in English | MEDLINE | ID: covidwho-683522

ABSTRACT

In March 2020, the WHO declared the COVID-19 disease as a pandemic disease. There have been studies on the COVID-19 to find a certain treatment, but yet, there is no certain cure. In this article, we present a possible way to treat severe cases of COVID-19. Based on the previous studies, there are similarities between the spike antigens of SARS-CoV and SARS-CoV-2 viruses. It is expected that these similarities (structural and affinity to the receptor of ACE2) can lead to the same pathophysiological activity of the virus by the use of ACE2 and FcγRII (the antibody-dependent enhancement mechanism). Therefore, we propose a way of washing out (by plasmapheresis) the possible antibodies against the spike protein of the virus out of patients' plasma to stop the antibody-dependent enhancement (ADE)-mediated infection of the immune system cells at the first phase of the treatment and simultaneous use of the anti-ACE2 with anti-FcγRII monoclonal antibodies at the second phase. We propose these procedures for the patients that have no significant response for typical anti-viral, ARDS and conservative therapies, and the disease persists or progresses despite sufficient therapies.


Subject(s)
Antibodies, Monoclonal/administration & dosage , Coronavirus Infections/therapy , Plasmapheresis/methods , Pneumonia, Viral/therapy , Antibodies, Monoclonal/immunology , Antibodies, Viral/immunology , Antigens, Viral/immunology , Coronavirus Infections/immunology , Coronavirus Infections/virology , Humans , Pandemics , Peptidyl-Dipeptidase A/immunology , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , Receptors, IgG/immunology , Severity of Illness Index
11.
Nature ; 584(7821): 450-456, 2020 08.
Article in English | MEDLINE | ID: covidwho-664494

ABSTRACT

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic continues, with devasting consequences for human lives and the global economy1,2. The discovery and development of virus-neutralizing monoclonal antibodies could be one approach to treat or prevent infection by this coronavirus. Here we report the isolation of sixty-one SARS-CoV-2-neutralizing monoclonal antibodies from five patients infected with SARS-CoV-2 and admitted to hospital with severe coronavirus disease 2019 (COVID-19). Among these are nineteen antibodies that potently neutralized authentic SARS-CoV-2 in vitro, nine of which exhibited very high potency, with 50% virus-inhibitory concentrations of 0.7 to 9 ng ml-1. Epitope mapping showed that this collection of nineteen antibodies was about equally divided between those directed against the receptor-binding domain (RBD) and those directed against the N-terminal domain (NTD), indicating that both of these regions at the top of the viral spike are immunogenic. In addition, two other powerful neutralizing antibodies recognized quaternary epitopes that overlap with the domains at the top of the spike. Cryo-electron microscopy reconstructions of one antibody that targets the RBD, a second that targets the NTD, and a third that bridges two separate RBDs showed that the antibodies recognize the closed, 'all RBD-down' conformation of the spike. Several of these monoclonal antibodies are promising candidates for clinical development as potential therapeutic and/or prophylactic agents against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Epitopes, B-Lymphocyte/immunology , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/ultrastructure , Antibodies, Neutralizing/analysis , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/ultrastructure , Antibodies, Viral/analysis , Antibodies, Viral/chemistry , Antibodies, Viral/ultrastructure , Betacoronavirus/chemistry , Betacoronavirus/ultrastructure , Coronavirus Infections/prevention & control , Cryoelectron Microscopy , Disease Models, Animal , Epitope Mapping , Epitopes, B-Lymphocyte/chemistry , Epitopes, B-Lymphocyte/ultrastructure , Female , Humans , Immunoglobulin Fab Fragments/chemistry , Immunoglobulin Fab Fragments/immunology , Immunoglobulin Fab Fragments/ultrastructure , Lung/pathology , Lung/virology , Male , Mesocricetus , Models, Molecular , Neutralization Tests , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Spike Glycoprotein, Coronavirus/ultrastructure
12.
Nature ; 584(7821): 443-449, 2020 08.
Article in English | MEDLINE | ID: covidwho-647154

ABSTRACT

The ongoing pandemic of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major threat to global health1 and the medical countermeasures available so far are limited2,3. Moreover, we currently lack a thorough understanding of the mechanisms of humoral immunity to SARS-CoV-24. Here we analyse a large panel of human monoclonal antibodies that target the spike (S) glycoprotein5, and identify several that exhibit potent neutralizing activity and fully block the receptor-binding domain of the S protein (SRBD) from interacting with human angiotensin-converting enzyme 2 (ACE2). Using competition-binding, structural and functional studies, we show that the monoclonal antibodies can be clustered into classes that recognize distinct epitopes on the SRBD, as well as distinct conformational states of the S trimer. Two potently neutralizing monoclonal antibodies, COV2-2196 and COV2-2130, which recognize non-overlapping sites, bound simultaneously to the S protein and neutralized wild-type SARS-CoV-2 virus in a synergistic manner. In two mouse models of SARS-CoV-2 infection, passive transfer of COV2-2196, COV2-2130 or a combination of both of these antibodies protected mice from weight loss and reduced the viral burden and levels of inflammation in the lungs. In addition, passive transfer of either of two of the most potent ACE2-blocking monoclonal antibodies (COV2-2196 or COV2-2381) as monotherapy protected rhesus macaques from SARS-CoV-2 infection. These results identify protective epitopes on the SRBD and provide a structure-based framework for rational vaccine design and the selection of robust immunotherapeutic agents.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Coronavirus Infections/prevention & control , Pandemics/prevention & control , Pneumonia, Viral/immunology , Pneumonia, Viral/prevention & control , Animals , Antibodies, Monoclonal/immunology , Betacoronavirus/chemistry , Binding, Competitive , Cell Line , Cross Reactions , Disease Models, Animal , Epitopes, B-Lymphocyte/chemistry , Epitopes, B-Lymphocyte/immunology , Female , Humans , Macaca mulatta , Male , Mice , Middle Aged , Neutralization Tests , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , Pre-Exposure Prophylaxis , SARS Virus/chemistry , SARS Virus/immunology , Severe Acute Respiratory Syndrome/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
14.
Cell Rep ; 32(3): 107918, 2020 07 21.
Article in English | MEDLINE | ID: covidwho-625076

ABSTRACT

Coronavirus disease 2019 (COVID-19) has become a worldwide threat to humans, and neutralizing antibodies have therapeutic potential. We have purified more than 1,000 memory B cells specific to SARS-CoV-2 S1 or its RBD (receptor binding domain) and obtain 729 paired heavy- and light-chain fragments. Among these, 178 antibodies test positive for antigen binding, and the majority of the top 17 binders with EC50 below 1 nM are RBD binders. Furthermore, we identify 11 neutralizing antibodies, eight of which show IC50 within 10 nM, and the best one, 414-1, with IC50 of 1.75 nM. Through epitope mapping, we find three main epitopes in RBD recognized by these antibodies, and epitope-B antibody 553-15 could substantially enhance the neutralizing abilities of most of the other antibodies. We also find that 515-5 could cross neutralize the SARS-CoV pseudovirus. Altogether, our study provides 11 potent human neutralizing antibodies for COVID-19 as therapeutic candidates.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Receptors, Virus/immunology , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Monoclonal/therapeutic use , B-Lymphocytes/immunology , Coronavirus Infections/therapy , Epitope Mapping , Epitopes/immunology , Humans , Immunologic Memory/immunology , Neutralization Tests , Pandemics , Pneumonia, Viral/therapy , Protein Domains/immunology
15.
J Immunol ; 205(4): 915-922, 2020 08 15.
Article in English | MEDLINE | ID: covidwho-616100

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for millions of infections and hundreds of thousands of deaths globally. There are no widely available licensed therapeutics against SARS-CoV-2, highlighting an urgent need for effective interventions. The virus enters host cells through binding of a receptor-binding domain within its trimeric spike glycoprotein to human angiotensin-converting enzyme 2. In this article, we describe the generation and characterization of a panel of murine mAbs directed against the receptor-binding domain. One mAb, 2B04, neutralized wild-type SARS-CoV-2 in vitro with remarkable potency (half-maximal inhibitory concentration of <2 ng/ml). In a murine model of SARS-CoV-2 infection, 2B04 protected challenged animals from weight loss, reduced lung viral load, and blocked systemic dissemination. Thus, 2B04 is a promising candidate for an effective antiviral that can be used to prevent SARS-CoV-2 infection.


Subject(s)
Antibodies, Monoclonal/therapeutic use , Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/therapeutic use , Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Coronavirus Infections/immunology , Pneumonia, Viral/drug therapy , Pneumonia, Viral/immunology , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/pharmacology , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/immunology , Antibodies, Viral/pharmacology , Chlorocebus aethiops , Coronavirus Infections/virology , Disease Models, Animal , Epitope Mapping , Female , HEK293 Cells , Humans , Immunodominant Epitopes/immunology , Mice , Mice, Inbred C57BL , Pandemics , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/virology , Protein Interaction Domains and Motifs/genetics , Protein Interaction Domains and Motifs/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Transfection , Vero Cells
17.
Science ; 369(6504): 650-655, 2020 08 07.
Article in English | MEDLINE | ID: covidwho-610891

ABSTRACT

Developing therapeutics against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be guided by the distribution of epitopes, not only on the receptor binding domain (RBD) of the Spike (S) protein but also across the full Spike (S) protein. We isolated and characterized monoclonal antibodies (mAbs) from 10 convalescent COVID-19 patients. Three mAbs showed neutralizing activities against authentic SARS-CoV-2. One mAb, named 4A8, exhibits high neutralization potency against both authentic and pseudotyped SARS-CoV-2 but does not bind the RBD. We defined the epitope of 4A8 as the N-terminal domain (NTD) of the S protein by determining with cryo-eletron microscopy its structure in complex with the S protein to an overall resolution of 3.1 angstroms and local resolution of 3.3 angstroms for the 4A8-NTD interface. This points to the NTD as a promising target for therapeutic mAbs against COVID-19.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Adult , Animals , Antibodies, Monoclonal/blood , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/metabolism , Antibodies, Viral/blood , Antibodies, Viral/chemistry , Antibodies, Viral/metabolism , Antibody Affinity , Antibody Specificity , Antigens, Viral/immunology , B-Lymphocytes/immunology , Chlorocebus aethiops , Coronavirus Infections/therapy , Cryoelectron Microscopy , Enzyme-Linked Immunosorbent Assay , Genes, Immunoglobulin Heavy Chain , Humans , Immunologic Memory , Middle Aged , Mutation , Nucleocapsid Proteins/immunology , Pandemics , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/therapy , Protein Domains , Protein Interaction Domains and Motifs/immunology , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells , Young Adult
18.
Immunity ; 53(1): 98-105.e5, 2020 07 14.
Article in English | MEDLINE | ID: covidwho-607661

ABSTRACT

Antibody responses develop following SARS-CoV-2 infection, but little is known about their epitope specificities, clonality, binding affinities, epitopes, and neutralizing activity. We isolated B cells specific for the SARS-CoV-2 envelope glycoprotein spike (S) from a COVID-19-infected subject 21 days after the onset of clinical disease. 45 S-specific monoclonal antibodies were generated. They had undergone minimal somatic mutation with limited clonal expansion, and three bound the receptor-binding domain (RBD). Two antibodies neutralized SARS-CoV-2. The most potent antibody bound the RBD and prevented binding to the ACE2 receptor, while the other bound outside the RBD. Thus, most anti-S antibodies that were generated in this patient during the first weeks of COVID-19 infection were non-neutralizing and target epitopes outside the RBD. Antibodies that disrupt the SARS-CoV-2 S-ACE2 interaction can potently neutralize the virus without undergoing extensive maturation. Such antibodies have potential preventive and/or therapeutic potential and can serve as templates for vaccine design.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Somatic Hypermutation, Immunoglobulin/genetics , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Monoclonal/immunology , B-Lymphocytes/immunology , Binding Sites , Coronavirus Infections/immunology , Coronavirus Infections/prevention & control , Epitopes, B-Lymphocyte/immunology , Humans , Pandemics/prevention & control , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/immunology , Pneumonia, Viral/prevention & control , Protein Binding , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Viral Vaccines/immunology
19.
Nature ; 584(7821): 437-442, 2020 08.
Article in English | MEDLINE | ID: covidwho-606946

ABSTRACT

During the coronavirus disease-2019 (COVID-19) pandemic, severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has led to the infection of millions of people and has claimed hundreds of thousands of lives. The entry of the virus into cells depends on the receptor-binding domain (RBD) of the spike (S) protein of SARS-CoV-2. Although there is currently no vaccine, it is likely that antibodies will be essential for protection. However, little is known about the human antibody response to SARS-CoV-21-5. Here we report on 149 COVID-19-convalescent individuals. Plasma samples collected an average of 39 days after the onset of symptoms had variable half-maximal pseudovirus neutralizing titres; titres were less than 50 in 33% of samples, below 1,000 in 79% of samples and only 1% of samples had titres above 5,000. Antibody sequencing revealed the expansion of clones of RBD-specific memory B cells that expressed closely related antibodies in different individuals. Despite low plasma titres, antibodies to three distinct epitopes on the RBD neutralized the virus with half-maximal inhibitory concentrations (IC50 values) as low as 2 ng ml-1. In conclusion, most convalescent plasma samples obtained from individuals who recover from COVID-19 do not contain high levels of neutralizing activity. Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , Adolescent , Adult , Aged , Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/analysis , Antibodies, Viral/analysis , Antibody Specificity , Coronavirus Infections/prevention & control , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle Aged , Neutralization Tests , Pandemics , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Viral Vaccines/immunology , Young Adult
20.
Science ; 369(6504): 643-650, 2020 08 07.
Article in English | MEDLINE | ID: covidwho-599037

ABSTRACT

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.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/immunology , Adult , Aged , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Antibody Affinity , Antigens, Viral/immunology , B-Lymphocyte Subsets/immunology , Broadly Neutralizing Antibodies/immunology , Cell Line, Tumor , Coronavirus Infections/prevention & control , Coronavirus Infections/therapy , Epitopes/immunology , Female , Humans , Immunologic Memory , Immunophenotyping , Male , Middle Aged , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/therapy , Protein Domains , Protein Interaction Domains and Motifs/immunology , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/chemistry
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