Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 11 de 11
Filter
1.
Int J Mol Sci ; 22(16)2021 Aug 13.
Article in English | MEDLINE | ID: covidwho-1662675

ABSTRACT

Iron oxide nanoparticles and single domain antibodies from camelids (VHHs) have been increasingly recognized for their potential uses for medical diagnosis and treatment. However, there have been relatively few detailed characterizations of their pharmacokinetics (PK). The aim of this study was to develop imaging methods and pharmacokinetic models to aid the future development of a novel family of brain MRI molecular contrast agents. An efficient near-infrared (NIR) imaging method was established to monitor VHH and VHH conjugated nanoparticle kinetics in mice using a hybrid approach: kinetics in blood were assessed by direct sampling, and kinetics in kidney, liver, and brain were assessed by serial in vivo NIR imaging. These studies were performed under "basal" circumstances in which the VHH constructs and VHH-conjugated nanoparticles do not substantially interact with targets nor cross the blood brain barrier. Using this approach, we constructed a five-compartment PK model that fits the data well for single VHHs, engineered VHH trimers, and iron oxide nanoparticles conjugated to VHH trimers. The establishment of the feasibility of these methods lays a foundation for future PK studies of candidate brain MRI molecular contrast agents.


Subject(s)
Camelids, New World/immunology , Kidney/chemistry , Liver/chemistry , Magnetic Iron Oxide Nanoparticles/chemistry , Single-Domain Antibodies/administration & dosage , Administration, Intravenous , Animals , Brain Chemistry , Female , Fluorometry , Humans , Mice , Models, Theoretical , Particle Size , Single-Domain Antibodies/blood , Single-Domain Antibodies/chemistry
2.
Elife ; 102021 12 07.
Article in English | MEDLINE | ID: covidwho-1555771

ABSTRACT

The emergence of SARS-CoV-2 variants threatens current vaccines and therapeutic antibodies and urgently demands powerful new therapeutics that can resist viral escape. We therefore generated a large nanobody repertoire to saturate the distinct and highly conserved available epitope space of SARS-CoV-2 spike, including the S1 receptor binding domain, N-terminal domain, and the S2 subunit, to identify new nanobody binding sites that may reflect novel mechanisms of viral neutralization. Structural mapping and functional assays show that indeed these highly stable monovalent nanobodies potently inhibit SARS-CoV-2 infection, display numerous neutralization mechanisms, are effective against emerging variants of concern, and are resistant to mutational escape. Rational combinations of these nanobodies that bind to distinct sites within and between spike subunits exhibit extraordinary synergy and suggest multiple tailored therapeutic and prophylactic strategies.


Subject(s)
COVID-19/immunology , SARS-CoV-2/immunology , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Binding Sites , Camelids, New World/immunology , Epitopes/genetics , Epitopes/immunology , HEK293 Cells , Humans , Male , Neutralization Tests , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
3.
Proc Natl Acad Sci U S A ; 118(44)2021 11 02.
Article in English | MEDLINE | ID: covidwho-1470027

ABSTRACT

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in over 100 million infections and millions of deaths. Effective vaccines remain the best hope of curtailing SARS-CoV-2 transmission, morbidity, and mortality. The vaccines in current use require cold storage and sophisticated manufacturing capacity, which complicates their distribution, especially in less developed countries. We report the development of a candidate SARS-CoV-2 vaccine that is purely protein based and directly targets antigen-presenting cells. It consists of the SARS-CoV-2 Spike receptor-binding domain (SpikeRBD) fused to an alpaca-derived nanobody that recognizes class II major histocompatibility complex antigens (VHHMHCII). This vaccine elicits robust humoral and cellular immunity against SARS-CoV-2 and its variants. Both young and aged mice immunized with two doses of VHHMHCII-SpikeRBD elicit high-titer binding and neutralizing antibodies. Immunization also induces strong cellular immunity, including a robust CD8 T cell response. VHHMHCII-SpikeRBD is stable for at least 7 d at room temperature and can be lyophilized without loss of efficacy.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19 Vaccines/pharmacology , COVID-19/immunology , COVID-19/prevention & control , Pandemics , SARS-CoV-2/immunology , Amino Acid Sequence , Animals , Antibodies, Neutralizing/biosynthesis , Antibodies, Viral/biosynthesis , Antigen-Presenting Cells/immunology , CD8-Positive T-Lymphocytes/immunology , COVID-19/epidemiology , COVID-19 Vaccines/administration & dosage , Camelids, New World/immunology , Female , Histocompatibility Antigens Class II/immunology , Humans , Immunity, Cellular , Immunity, Humoral , Immunization, Secondary , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic , Pandemics/prevention & control , Recombinant Fusion Proteins/administration & dosage , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/immunology , SARS-CoV-2/genetics , Single-Domain Antibodies/administration & dosage , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/administration & dosage , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
4.
EMBO J ; 40(19): e107985, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1323478

ABSTRACT

Monoclonal anti-SARS-CoV-2 immunoglobulins represent a treatment option for COVID-19. However, their production in mammalian cells is not scalable to meet the global demand. Single-domain (VHH) antibodies (also called nanobodies) provide an alternative suitable for microbial production. Using alpaca immune libraries against the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein, we isolated 45 infection-blocking VHH antibodies. These include nanobodies that can withstand 95°C. The most effective VHH antibody neutralizes SARS-CoV-2 at 17-50 pM concentration (0.2-0.7 µg per liter), binds the open and closed states of the Spike, and shows a tight RBD interaction in the X-ray and cryo-EM structures. The best VHH trimers neutralize even at 40 ng per liter. We constructed nanobody tandems and identified nanobody monomers that tolerate the K417N/T, E484K, N501Y, and L452R immune-escape mutations found in the Alpha, Beta, Gamma, Epsilon, Iota, and Delta/Kappa lineages. We also demonstrate neutralization of the Beta strain at low-picomolar VHH concentrations. We further discovered VHH antibodies that enforce native folding of the RBD in the E. coli cytosol, where its folding normally fails. Such "fold-promoting" nanobodies may allow for simplified production of vaccines and their adaptation to viral escape-mutations.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Mutation/immunology , SARS-CoV-2/immunology , Single-Domain Antibodies/immunology , Animals , COVID-19/virology , Camelids, New World/immunology , Camelids, New World/virology , Cell Line , Escherichia coli/virology , Female , Humans , Spike Glycoprotein, Coronavirus/immunology
5.
Nature ; 595(7866): 278-282, 2021 07.
Article in English | MEDLINE | ID: covidwho-1258586

ABSTRACT

Since the start of the COVID-19 pandemic, SARS-CoV-2 has caused millions of deaths worldwide. Although a number of vaccines have been deployed, the continual evolution of the receptor-binding domain (RBD) of the virus has challenged their efficacy. In particular, the emerging variants B.1.1.7, B.1.351 and P.1 (first detected in the UK, South Africa and Brazil, respectively) have compromised the efficacy of sera from patients who have recovered from COVID-19 and immunotherapies that have received emergency use authorization1-3. One potential alternative to avert viral escape is the use of camelid VHHs (variable heavy chain domains of heavy chain antibody (also known as nanobodies)), which can recognize epitopes that are often inaccessible to conventional antibodies4. Here, we isolate anti-RBD nanobodies from llamas and from mice that we engineered to produce VHHs cloned from alpacas, dromedaries and Bactrian camels. We identified two groups of highly neutralizing nanobodies. Group 1 circumvents antigenic drift by recognizing an RBD region that is highly conserved in coronaviruses but rarely targeted by human antibodies. Group 2 is almost exclusively focused to the RBD-ACE2 interface and does not neutralize SARS-CoV-2 variants that carry E484K or N501Y substitutions. However, nanobodies in group 2 retain full neutralization activity against these variants when expressed as homotrimers, and-to our knowledge-rival the most potent antibodies against SARS-CoV-2 that have been produced to date. These findings suggest that multivalent nanobodies overcome SARS-CoV-2 mutations through two separate mechanisms: enhanced avidity for the ACE2-binding domain and recognition of conserved epitopes that are largely inaccessible to human antibodies. Therefore, although new SARS-CoV-2 mutants will continue to emerge, nanobodies represent promising tools to prevent COVID-19 mortality when vaccines are compromised.


Subject(s)
Antibodies, Neutralizing/immunology , Camelids, New World/immunology , SARS-CoV-2/immunology , Single-Domain Antibodies/chemistry , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/isolation & purification , CRISPR-Cas Systems , Camelids, New World/genetics , Female , Gene Editing , Humans , Male , Mice , Mice, Inbred C57BL , Models, Molecular , Mutation , Neutralization Tests , SARS-CoV-2/chemistry , SARS-CoV-2/genetics , Single-Domain Antibodies/genetics , Single-Domain Antibodies/isolation & purification , Somatic Hypermutation, Immunoglobulin/genetics
6.
PLoS Pathog ; 17(5): e1009229, 2021 05.
Article in English | MEDLINE | ID: covidwho-1239922

ABSTRACT

While MERS-CoV (Middle East respiratory syndrome Coronavirus) provokes a lethal disease in humans, camelids, the main virus reservoir, are asymptomatic carriers, suggesting a crucial role for innate immune responses in controlling the infection. Experimentally infected camelids clear infectious virus within one week and mount an effective adaptive immune response. Here, transcription of immune response genes was monitored in the respiratory tract of MERS-CoV infected alpacas. Concomitant to the peak of infection, occurring at 2 days post inoculation (dpi), type I and III interferons (IFNs) were maximally transcribed only in the nasal mucosa of alpacas, while interferon stimulated genes (ISGs) were induced along the whole respiratory tract. Simultaneous to mild focal infiltration of leukocytes in nasal mucosa and submucosa, upregulation of the anti-inflammatory cytokine IL10 and dampened transcription of pro-inflammatory genes under NF-κB control were observed. In the lung, early (1 dpi) transcription of chemokines (CCL2 and CCL3) correlated with a transient accumulation of mainly mononuclear leukocytes. A tight regulation of IFNs in lungs with expression of ISGs and controlled inflammatory responses, might contribute to virus clearance without causing tissue damage. Thus, the nasal mucosa, the main target of MERS-CoV in camelids, seems central in driving an efficient innate immune response based on triggering ISGs as well as the dual anti-inflammatory effects of type III IFNs and IL10.


Subject(s)
Camelids, New World , Coronavirus Infections/immunology , Interferon Type I/metabolism , Interferons/metabolism , Middle East Respiratory Syndrome Coronavirus/immunology , Animals , Antiviral Agents/metabolism , Antiviral Agents/pharmacology , Camelids, New World/immunology , Camelids, New World/metabolism , Camelids, New World/virology , Chlorocebus aethiops , Coronavirus Infections/metabolism , Coronavirus Infections/prevention & control , Coronavirus Infections/veterinary , Disease Reservoirs/veterinary , Disease Resistance/drug effects , Disease Resistance/genetics , Disease Resistance/immunology , Gene Expression Regulation , Immunity, Innate/physiology , Inflammation/immunology , Inflammation/metabolism , Inflammation/veterinary , Inflammation/virology , Interferon Type I/genetics , Interferon Type I/pharmacology , Interferons/genetics , Interferons/pharmacology , Middle East Respiratory Syndrome Coronavirus/drug effects , Middle East Respiratory Syndrome Coronavirus/physiology , Nasal Mucosa/drug effects , Nasal Mucosa/immunology , Nasal Mucosa/metabolism , Nasal Mucosa/virology , Respiratory System/drug effects , Respiratory System/immunology , Respiratory System/metabolism , Respiratory System/virology , Vero Cells , Viral Load/drug effects , Virus Replication/drug effects
7.
Sci Rep ; 11(1): 3318, 2021 02 08.
Article in English | MEDLINE | ID: covidwho-1069119

ABSTRACT

Despite unprecedented global efforts to rapidly develop SARS-CoV-2 treatments, in order to reduce the burden placed on health systems, the situation remains critical. Effective diagnosis, treatment, and prophylactic measures are urgently required to meet global demand: recombinant antibodies fulfill these requirements and have marked clinical potential. Here, we describe the fast-tracked development of an alpaca Nanobody specific for the receptor-binding-domain (RBD) of the SARS-CoV-2 Spike protein with potential therapeutic applicability. We present a rapid method for nanobody isolation that includes an optimized immunization regimen coupled with VHH library E. coli surface display, which allows single-step selection of Nanobodies using a simple density gradient centrifugation of the bacterial library. The selected single and monomeric Nanobody, W25, binds to the SARS-CoV-2 S RBD with sub-nanomolar affinity and efficiently competes with ACE-2 receptor binding. Furthermore, W25 potently neutralizes SARS-CoV-2 wild type and the D614G variant with IC50 values in the nanomolar range, demonstrating its potential as antiviral agent.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Antibody Affinity/genetics , COVID-19/immunology , SARS-CoV-2/immunology , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/immunology , Angiotensin-Converting Enzyme 2/immunology , Animals , COVID-19/virology , Camelids, New World/immunology , Escherichia coli/genetics , Escherichia coli/metabolism , Green Fluorescent Proteins/genetics , HeLa Cells , Humans , Immunization , Male , Neutralization Tests , Peptide Library , Protein Binding/genetics , SARS-CoV-2/chemistry , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/genetics , Transfection
9.
Nat Commun ; 11(1): 4420, 2020 09 04.
Article in English | MEDLINE | ID: covidwho-744371

ABSTRACT

SARS-CoV-2 enters host cells through an interaction between the spike glycoprotein and the angiotensin converting enzyme 2 (ACE2) receptor. Directly preventing this interaction presents an attractive possibility for suppressing SARS-CoV-2 replication. Here, we report the isolation and characterization of an alpaca-derived single domain antibody fragment, Ty1, that specifically targets the receptor binding domain (RBD) of the SARS-CoV-2 spike, directly preventing ACE2 engagement. Ty1 binds the RBD with high affinity, occluding ACE2. A cryo-electron microscopy structure of the bound complex at 2.9 Å resolution reveals that Ty1 binds to an epitope on the RBD accessible in both the 'up' and 'down' conformations, sterically hindering RBD-ACE2 binding. While fusion to an Fc domain renders Ty1 extremely potent, Ty1 neutralizes SARS-CoV-2 spike pseudovirus as a 12.8 kDa nanobody, which can be expressed in high quantities in bacteria, presenting opportunities for manufacturing at scale. Ty1 is therefore an excellent candidate as an intervention against COVID-19.


Subject(s)
Angiotensin-Converting Enzyme Inhibitors/pharmacology , Betacoronavirus/drug effects , Camelids, New World/immunology , Coronavirus Infections/drug therapy , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/drug therapy , Single-Domain Antibodies/pharmacology , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Amino Acid Sequence , Angiotensin-Converting Enzyme 2 , Animals , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/chemistry , Antibodies, Viral/immunology , Betacoronavirus/immunology , Betacoronavirus/metabolism , Binding Sites , COVID-19 , Chlorocebus aethiops , Coronavirus Infections/virology , Cryoelectron Microscopy , Epitopes/immunology , Epitopes/metabolism , HEK293 Cells , Humans , Male , Models, Molecular , Pandemics , Peptidyl-Dipeptidase A/chemistry , Pneumonia, Viral/virology , Protein Binding , SARS-CoV-2 , Single-Domain Antibodies/immunology , Single-Domain Antibodies/isolation & purification , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
10.
Emerg Microbes Infect ; 9(1): 1034-1036, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-260384

ABSTRACT

Coronaviruses cause severe human viral diseases including SARS, MERS and COVID-19. Most recently SARS-CoV-2 virus (causing COVID-19) has led to a pandemic with no successful therapeutics. The SARS-CoV-2 infection relies on trimeric spike (S) proteins to facilitate virus entry into host cells by binding to ACE2 receptor on host cell membranes. Therefore, blocking this interaction with antibodies are promising agents against SARS-CoV-2. Here we describe using humanized llama antibody VHHs against SARS-CoV-2 that would overcome the limitations associated with polyclonal and monoclonal combination therapies. From two llama VHH libraries, unique humanized VHHs that bind to S protein and block the S/ACE2 interaction were identified. Furthermore, pairwise combination of VHHs showed synergistic blocking. Multi-specific antibodies with enhanced affinity and avidity, and improved S/ACE2 blocking are currently being developed using an in-silico approach that also fuses VHHs to Fc domains. Importantly, our current bi-specific antibody shows potent S/ACE2 blocking (KD - 0.25 nM, IC100 ∼ 36.7 nM, IC95 ∼ 12.2 nM, IC50 ∼ 1 nM) which is significantly better than individual monoclonal VHH-Fcs. Overall, this design would equip the VHH-Fcs multiple mechanisms of actions against SARS-CoV-2. Thus, we aim to contribute to the battle against COVID-19 by developing therapeutic antibodies as well as diagnostics.


Subject(s)
Angiotensin Receptor Antagonists/immunology , Antibodies, Monoclonal, Humanized/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Camelids, New World/immunology , Peptidyl-Dipeptidase A/immunology , Angiotensin-Converting Enzyme 2 , Animals , Antibodies, Bispecific/immunology , Humans , Peptidyl-Dipeptidase A/metabolism , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology
11.
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
SELECTION OF CITATIONS
SEARCH DETAIL