scholarly journals Neutralizing Antibodies Isolated by a site-directed Screening have Potent Protection on SARS-CoV-2 Infection

2020 ◽  
Author(s):  
Xiaoyu Liu ◽  
Fang Gao ◽  
Liming Gou ◽  
Yin Chen ◽  
Yayun Gu ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Host Cells ◽  
Igg Antibody ◽  
Angiotensin Converting Enzyme 2 ◽  
Antibody Screening ◽  
Effective Interventions ◽  
A Site ◽  
Potent Protection ◽  
Pathogenic Infection

AbstractNeutralizing antibody is one of the most effective interventions for acute pathogenic infection. Currently, over three million people have been identified for SARS-CoV-2 infection but SARS-CoV-2-specific vaccines and neutralizing antibodies are still lacking. SARS-CoV-2 infects host cells by interacting with angiotensin converting enzyme-2 (ACE2) via the S1 receptor-binding domain (RBD) of its surface spike glycoprotein. Therefore, blocking the interaction of SARS-CoV-2-RBD and ACE2 by antibody would cause a directly neutralizing effect against virus. In the current study, we selected the ACE2 interface of SARS-CoV-2-RBD as the targeting epitope for neutralizing antibody screening. We performed site-directed screening by phage display and finally obtained one IgG antibody (4A3) and several domain antibodies. Among them, 4A3 and three domain antibodies (4A12, 4D5, and 4A10) were identified to act as neutralizing antibodies due to their capabilities to block the interaction between SARS-CoV-2-RBD and ACE2-positive cells. The domain antibody 4A12 was predicted to have the best accessibility to all three ACE2-interfaces on the spike homotrimer. Pseudovirus and authentic SARS-CoV-2 neutralization assays showed that all four antibodies could potently protect host cells from virus infection. Overall, we isolated multiple formats of SARS-CoV-2-neutralizing antibodies via site-directed antibody screening, which could be promising candidate drugs for the prevention and treatment of COVID-19.

scholarly journals Molecular basis for a germline-biased neutralizing antibody response to SARS-CoV-2

2020 ◽  
Author(s):  
Sarah A. Clark ◽  
Lars E. Clark ◽  
Junhua Pan ◽  
Adrian Coscia ◽  
Lindsay G.A. McKay ◽  
...  
Keyword(s):  
Antibody Response ◽  
Molecular Basis ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Antiviral Effect ◽  
Host Cells ◽  
Human Antibody ◽  
Angiotensin Converting Enzyme 2 ◽  
Antibody Heavy Chain ◽  
Major Target

AbstractThe SARS-CoV-2 viral spike (S) protein mediates attachment and entry into host cells and is a major target of vaccine and drug design. Potent SARS-CoV-2 neutralizing antibodies derived from closely related antibody heavy chain genes (IGHV3-53 or 3-66) have been isolated from multiple COVID-19 convalescent individuals. These usually contain minimal somatic mutations and bind the S receptor-binding domain (RBD) to interfere with attachment to the cellular receptor angiotensin-converting enzyme 2 (ACE2). We used antigen-specific single B cell sorting to isolate S-reactive monoclonal antibodies from the blood of a COVID-19 convalescent individual. The seven most potent neutralizing antibodies were somatic variants of the same IGHV3-53-derived antibody and bind the RBD with varying affinity. We report X-ray crystal structures of four Fab variants bound to the RBD and use the structures to explain the basis for changes in RBD affinity. We show that a germline revertant antibody binds tightly to the SARS-CoV-2 RBD and neutralizes virus, and that gains in affinity for the RBD do not necessarily correlate with increased neutralization potency, suggesting that somatic mutation is not required to exert robust antiviral effect. Our studies clarify the molecular basis for a heavily germline-biased human antibody response to SARS-CoV-2.

scholarly journals Screening of potent neutralizing antibodies against SARS-CoV-2 using convalescent patients-derived phage-display libraries

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yongbing Pan ◽  
Jianhui Du ◽  
Jia Liu ◽  
Hai Wu ◽  
Fang Gui ◽  
...  
Keyword(s):  
Phage Display ◽  
Neutralizing Antibodies ◽  
Variable Region ◽  
Neutralizing Antibody ◽  
Chain Gene ◽  
Prophylactic Efficacy ◽  
Heavy Chains ◽  
Effective Interventions ◽  
Phage Display Libraries

AbstractAs the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to threaten public health worldwide, the development of effective interventions is urgently needed. Neutralizing antibodies (nAbs) have great potential for the prevention and treatment of SARS-CoV-2 infection. In this study, ten nAbs were isolated from two phage-display immune libraries constructed from the pooled PBMCs of eight COVID-19 convalescent patients. Eight of them, consisting of heavy chains encoded by the immunoglobulin heavy-chain gene-variable region (IGHV)3-66 or IGHV3-53 genes, recognized the same epitope on the receptor-binding domain (RBD), while the remaining two bound to different epitopes. Among the ten antibodies, 2B11 exhibited the highest affinity and neutralization potency against the original wild-type (WT) SARS-CoV-2 virus (KD = 4.76 nM for the S1 protein, IC50 = 6 ng/mL for pseudoviruses, and IC50 = 1 ng/mL for authentic viruses), and potent neutralizing ability against B.1.1.7 pseudoviruses. Furthermore, 1E10, targeting a distinct epitope on RBD, exhibited different neutralization efficiency against WT SARS-CoV-2 and its variants B.1.1.7, B.1.351, and P.1. The crystal structure of the 2B11–RBD complexes revealed that the epitope of 2B11 highly overlaps with the ACE2-binding site. The in vivo experiment of 2B11 using AdV5-hACE2-transduced mice showed encouraging therapeutic and prophylactic efficacy against SARS-CoV-2. Taken together, our results suggest that the highly potent SARS-CoV-2-neutralizing antibody, 2B11, could be used against the WT SARS-CoV-2 and B.1.1.7 variant, or in combination with a different epitope-targeted neutralizing antibody, such as 1E10, against SARS-CoV-2 variants.

scholarly journals Long-term persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein-specific and neutralizing antibodies in recovered COVID-19 patients

2021 ◽  
Author(s):  
Jira Chansaenroj ◽  
Ritthideach Yorsaeng ◽  
Nasamon Wanlapakorn ◽  
Chintana Chirathaworn ◽  
Natthinee Sudhinaraset ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Serum Antibody ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Spike Protein ◽  
Immunological Study ◽  
Igg Antibody ◽  
Vaccine Schedule

Abstract Understanding antibody responses after natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can guide the coronavirus disease 2019 (COVID-19) vaccine schedule. This study aimed to assess the dynamics of SARS-CoV-2 antibodies, including anti-spike protein 1 (S1) immunoglobulin (Ig)G, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody against wild-type SARS-CoV-2 in a cohort of patients who were previously infected with SARS-CoV-2. Between March and May 2020, 531 individuals with virologically confirmed cases of SARS-CoV-2 infection were enrolled in our immunological study. The neutralizing titers against SARS-CoV-2 were detected in 95.2%, 86.7%, 85.0%, and 85.4% of recovered COVID-19 patients at 3, 6, 9, and 12 months after symptom onset, respectively. The seropositivity rate of anti-S1 IgG, anti-RBD total Ig, anti-S1 IgA, and neutralizing titers remained at 68.6%, 89.6%, 77.1%, and 85.4%, respectively, at 12 months after symptom onset. The half-life of neutralizing titers was estimated at 100.7 days (95% confidence interval = 44.5 – 327.4 days, R2 = 0.106). These results support that the decline in serum antibody levels over time depends on the symptom severity, and the individuals with high IgG antibody titers experienced a significantly longer persistence of SARS-CoV-2-specific antibody responses than those with lower titers.

scholarly journals Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2270
Author(s):  
Gloria Griffante ◽  
Shikha Chandel ◽  
Daniela Ferrante ◽  
Valeria Caneparo ◽  
Daniela Capello ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Large Fraction ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Northern Italy ◽  
Serum Samples ◽  
Neutralization Titer ◽  
Igg Antibody

Longitudinal mapping of antibody-based SARS-CoV-2 immunity is critical for public health control of the pandemic and vaccine development. We performed a longitudinal analysis of the antibody-based immune response in a cohort of 100 COVID-19 individuals who were infected during the first wave of infection in northern Italy. The SARS-CoV-2 humoral response was tested using the COVID-SeroIndex, Kantaro Quantitative SARS-CoV-2 IgG Antibody RUO Kit (R&D Systems, Bio-Techne, Minneapolis, USA) and pseudotype-based neutralizing antibody assay. Using sequential serum samples collected from 100 COVID-19 recovered individuals from northern Italy—mostly with mild disease—at 2 and 10 months after their first positive PCR test, we show that 93% of them seroconverted at 2 months, with a geometric mean (GeoMean) half-maximal neutralization titer (NT50) of 387.9. Among the 35 unvaccinated subjects retested at 10 months, 7 resulted seronegative, with an 80% drop in seropositivity, while 28 showed decreased anti-receptor binding domain (RBD) and anti-spike (S) IgG titers, with a GeoMean NT50 neutralization titer dropping to 163.5. As an NT50 > 100 is known to confer protection from SARS-CoV-2 re-infection, our data show that the neutralizing activity elicited by the natural infection has lasted for at least 10 months in a large fraction of subjects.

scholarly journals Low-dose in vivo protection and neutralization across SARS-CoV-2 variants by monoclonal antibody combinations

2021 ◽  
Author(s):  
Vincent Dussupt ◽  
Rajeshwer S. Sankhala ◽  
Letzibeth Mendez-Rivera ◽  
Samantha M. Townsley ◽  
Fabian Schmidt ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Low Dose ◽  
Viral Escape ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Viral Inactivation ◽  
Angiotensin Converting Enzyme 2 ◽  
Therapeutic Monoclonal Antibodies ◽  
Potent Protection

AbstractPrevention of viral escape and increased coverage against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern require therapeutic monoclonal antibodies (mAbs) targeting multiple sites of vulnerability on the coronavirus spike glycoprotein. Here we identify several potent neutralizing antibodies directed against either the N-terminal domain (NTD) or the receptor-binding domain (RBD) of the spike protein. Administered in combinations, these mAbs provided low-dose protection against SARS-CoV-2 infection in the K18-human angiotensin-converting enzyme 2 mouse model, using both neutralization and Fc effector antibody functions. The RBD mAb WRAIR-2125, which targets residue F486 through a unique heavy-chain and light-chain pairing, demonstrated potent neutralizing activity against all major SARS-CoV-2 variants of concern. In combination with NTD and other RBD mAbs, WRAIR-2125 also prevented viral escape. These data demonstrate that NTD/RBD mAb combinations confer potent protection, likely leveraging complementary mechanisms of viral inactivation and clearance.

scholarly journals Structures of Two Human Astrovirus Capsid/Neutralizing Antibody Complexes Reveal Distinct Epitopes and Inhibition of Virus Attachment to Cells

2021 ◽  
Author(s):  
Lena Ricemeyer ◽  
Nayeli Aguilar-Hernández ◽  
Tomás López ◽  
Rafaela Espinosa ◽  
Sarah Lanning ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Host Cells ◽  
Viral Gastroenteritis ◽  
Receptor Binding Site ◽  
Virus Attachment ◽  
Human Astroviruses ◽  
Human Astrovirus

Human astrovirus is an important cause of viral gastroenteritis worldwide. Young children, the elderly, and the immunocompromised are especially at risk for contracting severe disease. However, no vaccines exist to combat human astrovirus infection. Evidence points to the importance of antibodies in enabling protection of healthy adults from reinfection. To develop an effective subunit vaccine that broadly protects against diverse astrovirus serotypes, we must understand how neutralizing antibodies target the capsid surface at the molecular level. Here, we report the structures of the human astrovirus capsid spike domain bound to two neutralizing monoclonal antibodies. These antibodies bind two distinct conformational epitopes on the spike surface. We add to existing evidence that the human astrovirus capsid spike contains a receptor-binding domain and demonstrate that both antibodies neutralize human astrovirus by blocking virus attachment to host cells. We identify patches of conserved amino acids that overlap or border the antibody epitopes and may constitute a receptor-binding site. Our findings provide a basis to develop therapies that prevent and treat human astrovirus gastroenteritis. Importance Human astroviruses infect nearly every person in the world during childhood and cause diarrhea, vomiting, and fever. Despite the prevalence of this virus, little is known about how antibodies block virus infection. Here, we determined crystal structures of the astrovirus capsid protein in complex with two virus-neutralizing antibodies. We show that the antibodies bind two distinct sites on the capsid spike domain; however, both antibodies block virus attachment to human cells. Importantly, our findings support the use of the human astrovirus capsid spike as an antigen in a subunit-based vaccine to prevent astrovirus disease.

scholarly journals Introduction of two prolines and removal of the polybasic cleavage site leads to optimal efficacy of a recombinant spike based SARS-CoV-2 vaccine in the mouse model

2020 ◽  
Author(s):  
Fatima Amanat ◽  
Shirin Strohmeier ◽  
Raveen Rathnasinghe ◽  
Michael Schotsaert ◽  
Lynda Coughlan ◽  
...  
Keyword(s):  
Mouse Model ◽  
Cleavage Site ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Middle Eastern ◽  
Host Cells ◽  
Spike Protein ◽  
Optimized Design ◽  
Angiotensin Converting Enzyme 2 ◽  
Viral Target

AbstractThe spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as the prime target for vaccine development. The spike protein mediates both binding to host cells and membrane fusion and is also so far the only known viral target of neutralizing antibodies. Coronavirus spike proteins are large trimers that are relatively instable, a feature that might be enhanced by the presence of a polybasic cleavage site in the SARS-CoV-2 spike. Exchange of K986 and V987 to prolines has been shown to stabilize the trimers of SARS-CoV-1 and the Middle Eastern respiratory syndrome coronavirus spikes. Here, we test multiple versions of a soluble spike protein for their immunogenicity and protective effect against SARS-CoV-2 challenge in a mouse model that transiently expresses human angiotensin converting enzyme 2 via adenovirus transduction. Variants tested include spike protein with a deleted polybasic cleavage site, the proline mutations, a combination thereof, as well as the wild type protein. While all versions of the protein were able to induce neutralizing antibodies, only the antigen with both a deleted cleavage site and the PP mutations completely protected from challenge in this mouse model.ImportanceA vaccine for SARS-CoV-2 is urgently needed. A better understanding of antigen design and attributes that vaccine candidates need to have to induce protective immunity is of high importance. The data presented here validates the choice of antigens that contain the PP mutation and suggests that deletion of the polybasic cleavage site could lead to a further optimized design.

scholarly journals N-terminal domain antigenic mapping reveals a site of vulnerability for SARS-CoV-2

2021 ◽  
Author(s):  
Matthew McCallum ◽  
Anna De Marco ◽  
Florian Lempp ◽  
M. Alejandra Tortorici ◽  
Dora Pinto ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Selective Pressure ◽  
Memory B Cells ◽  
Host Cells ◽  
Receptor Binding Domain ◽  
Effector Functions ◽  
Terminal Domain ◽  
Frequent Mutations ◽  
A Site

SARS-CoV-2 entry into host cells is orchestrated by the spike (S) glycoprotein that contains an immunodominant receptor-binding domain (RBD) targeted by the largest fraction of neutralizing antibodies (Abs) in COVID-19 patient plasma. Little is known about neutralizing Abs binding to epitopes outside the RBD and their contribution to protection. Here, we describe 41 human monoclonal Abs (mAbs) derived from memory B cells, which recognize the SARS-CoV-2 S N-terminal domain (NTD) and show that a subset of them neutralize SARS-CoV-2 ultrapotently. We define an antigenic map of the SARS-CoV-2 NTD and identify a supersite recognized by all known NTD-specific neutralizing mAbs. These mAbs inhibit cell-to-cell fusion, activate effector functions, and protect Syrian hamsters from SARS-CoV-2 challenge. SARS-CoV-2 variants, including the 501Y.V2 and B.1.1.7 lineages, harbor frequent mutations localized in the NTD supersite suggesting ongoing selective pressure and the importance of NTD-specific neutralizing mAbs to protective immunity.

scholarly journals Emerging antibody-based therapeutics against SARS-CoV-2 during the global pandemic

2020 ◽  
Vol 3 (4) ◽  
pp. 246-256
Author(s):  
Yaping Sun ◽  
Mitchell Ho
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Host Cells ◽  
Spike Protein ◽  
Inhaled Drugs ◽  
Viral Attachment ◽  
Global Pandemic ◽  
Attachment Sites ◽  
Antibody Discovery

Abstract SARS-CoV-2 antibody therapeutics are being evaluated in clinical and preclinical stages. As of 11 October 2020, 13 human monoclonal antibodies targeting the SARS-CoV-2 spike protein have entered clinical trials with three (REGN-COV2, LY3819253/LY-CoV555, and VIR-7831/VIR-7832) in phase 3. On 9 November 2020, the US Food and Drug Administration issued an emergency use authorization for bamlanivimab (LY3819253/LY-CoV555) for the treatment of mild-to-moderate COVID-19. This review outlines the development of neutralizing antibodies against SARS-CoV-2, with a focus on discussing various antibody discovery strategies (animal immunization, phage display and B cell cloning), describing binding epitopes and comparing neutralizing activities. Broad-neutralizing antibodies targeting the spike proteins of SARS-CoV-2 and SARS-CoV might be helpful for treating COVID-19 and future infections. VIR-7831/7832 based on S309 is the only antibody in late clinical development, which can neutralize both SARS-CoV-2 and SARS-CoV although it does not directly block virus receptor binding. Thus far, the only cross-neutralizing antibody that is also a receptor binding blocker is nanobody VHH-72. The feasibility of developing nanobodies as inhaled drugs for treating COVID-19 and other respiratory diseases is an attractive idea that is worth exploring and testing. A cocktail strategy such as REGN-COV2, or engineered multivalent and multispecific molecules, combining two or more antibodies might improve the efficacy and protect against resistance due to virus escape mutants. Besides the receptor-binding domain, other viral antigens such as the S2 subunit of the spike protein and the viral attachment sites such as heparan sulfate proteoglycans that are on the host cells are worth investigating.

scholarly journals Introduction of Two Prolines and Removal of the Polybasic Cleavage Site Lead to Higher Efficacy of a Recombinant Spike-Based SARS-CoV-2 Vaccine in the Mouse Model

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Fatima Amanat ◽  
Shirin Strohmeier ◽  
Raveen Rathnasinghe ◽  
Michael Schotsaert ◽  
Lynda Coughlan ◽  
...  
Keyword(s):  
Mouse Model ◽  
Cleavage Site ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Host Cells ◽  
Spike Protein ◽  
Optimized Design ◽  
Angiotensin Converting Enzyme 2 ◽  
Viral Target ◽  
Spike Proteins

ABSTRACT The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as the prime target for vaccine development. The spike protein mediates both binding to host cells and membrane fusion and is also so far the only known viral target of neutralizing antibodies. Coronavirus spike proteins are large trimers that are relatively unstable, a feature that might be enhanced by the presence of a polybasic cleavage site in SARS-CoV-2 spike. Exchange of K986 and V987 for prolines has been shown to stabilize the trimers of SARS-CoV-1 and the Middle East respiratory syndrome coronavirus spike proteins. Here, we test multiple versions of a soluble spike protein for their immunogenicity and protective effect against SARS-CoV-2 challenge in a mouse model that transiently expresses human angiotensin-converting enzyme 2 via adenovirus transduction. Variants tested include spike proteins with a deleted polybasic cleavage site, proline mutations, or a combination thereof, besides the wild-type protein. While all versions of the protein were able to induce neutralizing antibodies, only the antigen with both a deleted cleavage site and the K986P and V987P (PP) mutations completely protected from challenge in this mouse model. IMPORTANCE A vaccine for SARS-CoV-2 is urgently needed. A better understanding of antigen design and attributes that vaccine candidates need to have to induce protective immunity is of high importance. The data presented here validate the choice of antigens that contain the PP mutations and suggest that deletion of the polybasic cleavage site may lead to a further-optimized design.

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