scholarly journals Monoclonal Antibody 667 Recognizes the Variable Region A Motif of the Ecotropic Retrovirus CasBrE Envelope Glycoprotein and Inhibits Env Binding to the Viral Receptor

2003 ◽  
Vol 77 (20) ◽  
pp. 10984-10993 ◽  
Author(s):  
Hanna Dreja ◽  
Laurent Gros ◽  
Sylvie Villard ◽  
Estanislao Bachrach ◽  
Anna Oates ◽  
...  
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Envelope Glycoprotein ◽  
Critical Role ◽  
Variable Region ◽  
Binding Domain ◽  
Target Cells ◽  
Kinetic Properties ◽  
Receptor Binding Domain

ABSTRACT Monoclonal antibody (MAb) 667 is a neutralizing mouse monoclonal antibody recognizing the envelope glycoprotein (Env) of the ecotropic neurotropic murine retrovirus CasBrE but not that of other murine retroviruses. Since 667 can be used for preclinical studies of antiviral gene therapy as well as for studying the early events of retroviral infection, we have cloned its cDNAs and molecularly characterized it in detail. Spot technique-based experiments showed that 667 recognizes a linear epitope of 12 amino acids located in the variable region A of the receptor binding domain. Alanine scanning experiments showed that six amino acids within the epitope are critical for MAb binding. One of them, D57, is not present in any other murine retroviral Env, which suggests a critical role for this residue in the selectivity of 667. MAb 667 heavy- and light-chain cDNAs were functionally characterized by transient transfection into Cos-7 cells. Enzyme-linked immunosorbent assays and Biacore studies showed that the specificities as well as the antigen-binding thermodynamic and kinetic properties of the recombinant 667 MAb (r667) produced by Cos-7 cells and those of the parental hybridoma-produced MAb (h667) were similar. However, h667 was shown to contain contaminating retroviral and/or retrovirus-like particles which interfere with both viral binding and neutralization experiments. These contaminants could successfully be removed by a stringent purification protocol. Importantly, this purified 667 could completely prevent retrovirus binding to target cells and was as efficient as the r667 MAb produced by transfected Cos-7 cells in neutralization assays. In conclusion, this study shows that the primary mechanism of virus neutralization by MAb 667 is the blocking of the retroviral receptor binding domain of CasBrE Env. In addition, the findings of this study constitute a warning against the direct use of hybridoma cell culture supernatants for studying the initial events of retroviral cell infection as well as for carrying out in vivo neutralization experiments and suggest that either recombinant antibodies or highly purified antibodies are preferable for these purposes.

scholarly journals Gonococcal pili. Primary structure and receptor binding domain.

1984 ◽  
Vol 159 (5) ◽  
pp. 1351-1370 ◽  
Author(s):  
G K Schoolnik ◽  
R Fernandez ◽  
J Y Tai ◽  
J Rothbard ◽  
E C Gotschlich
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Binding Domain ◽  
Structural Basis ◽  
Receptor Binding Domain ◽  
Variable Regions ◽  
Disulfide Linkage ◽  
Polymeric Structure ◽  
Antigenic Diversity ◽  
Single Polypeptide Chain

The complete amino acid sequence of pilin from gonococcal strain MS11 and the sequence of constant and variable regions from strain R10 pilin have been determined in order to elucidate the structural basis for adherence function, antigenic diversity, and polymeric structure. The MS11 pilin sequence consists of 159 amino acids in a single polypeptide chain with two cysteines in disulfide linkage and serine-bonded phosphate residues. TC-2 (31-111), a soluble monomeric pilus peptide prepared by arginine-specific digestion, bound human endocervical, but not buccal or HeLa cells and therefore is postulated to encompass the receptor binding domain. Variable regions of CNBr-3 appear to confer antigenic diversity and comprise segments in which changes in the position of charged residues occur in hydrophilic, beta-turns. Residues 2-21 and 202-221 of gonococcal pilins and lower eucaryotic actins, respectively, exhibit 50% homology. When these residues are arranged at intervals of 100 degrees of arc on "helical wheels," the identical amino acids comprise a hydrophobic face on one side of the helix. This observation, the hydrophobic character of this region and the tendency for TC-1 (residues 1-30) to aggregate in water, suggest that this stretch interacts with other subunits to stabilize polymeric structure.

scholarly journals Functional analysis of the receptor binding domain of SARS coronavirus S1 region and its monoclonal antibody

2014 ◽  
Vol 36 (3) ◽  
pp. 387-397 ◽  
Author(s):  
Hyun Kim ◽  
Yeongjin Hong ◽  
Keigo Shibayama ◽  
Yasuhiko Suzuki ◽  
Nobutaka Wakamiya ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Functional Analysis ◽  
Receptor Binding ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Sars Coronavirus

scholarly journals Isolation of a human monoclonal antibody specific for the receptor binding domain of SARS-CoV-2 using a competitive phage biopanning strategy

2020 ◽  
Vol 3 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Xin Zeng ◽  
Lingfang Li ◽  
Jing Lin ◽  
Xinlei Li ◽  
Bin Liu ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Magnetic Beads ◽  
Human Monoclonal Antibody ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Antibody Library ◽  
Synthetic Antibody ◽  
Blocking Antibodies

Abstract The infection of the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused more than 200 000 deaths, but no vaccine or therapeutic monoclonal antibody is currently available. SARS-CoV-2 relies on its spike protein, in particular the receptor-binding domain (RBD), to bind human cell receptor angiotensin-converting enzyme 2 (ACE2) for viral entry, and thus targeting RBD holds the promise for preventing SARS-CoV-2 infection. In this work, a competitive biopanning strategy of a phage display antibody library was applied to screen blocking antibodies against RBD. High-affinity antibodies were enriched after the first round using a standard panning process in which RBD-His was immobilized as a bait. At the next two rounds, immobilized ACE2-Fc and free RBD-His were mixed with the enriched phage antibodies. Antibodies binding to RBD at epitopes different from ACE2-binding site were captured by the immobilized ACE2-Fc, forming a “sandwich” complex. Only antibodies competed with ACE2 can bind to the free RBD-His in the supernatant and be subsequently separated by the nickel-nitrilotriacetic acid magnetic beads. rRBD-15 from the competitive biopanning of our synthetic antibody library, Lib AB1, was produced as the full-length IgG1 format. It was proved to competitively block the binding of RBD to ACE2 and potently inhibit SARS-CoV-2 pseudovirus infection with IC50 values of 12 nM. Nevertheless, rRBD-16 from the standard biopanning can only bind to RBD in vitro, but not have the blocking or neutralization activity. Our strategy can efficiently isolate the blocking antibodies of RBD, and it would speed up the discovery of neutralizing antibodies against SARS-CoV-2.

scholarly journals SARS-CoV-2, an evolutionary perspective of interaction with human ACE2 reveals undiscovered amino acids necessary for complex stability

2020 ◽  
Author(s):  
Vinicio Armijos-Jaramillo ◽  
Justin Yeager ◽  
Claire Muslin ◽  
Yunierkis Perez-Castillo
Keyword(s):  
Receptor Binding ◽  
Evolutionary Dynamics ◽  
Hot Spot ◽  
Critical Role ◽  
Human Cells ◽  
Binding Domain ◽  
Host Cells ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Salt Bridges

AbstractThe emergence of SARS-CoV-2 has resulted in more than 200,000 infections and nearly 9,000 deaths globally so far. This novel virus is thought to have originated from an animal reservoir, and acquired the ability to infect human cells using the SARS-CoV cell receptor hACE2. In the wake of a global pandemic it is essential to improve our understanding of the evolutionary dynamics surrounding the origin and spread of a novel infectious disease. One way theory predicts selection pressures should shape viral evolution is to enhance binding with host cells. We first assessed evolutionary dynamics in select betacoronavirus spike protein genes to predict where these genomic regions are under directional or purifying selection between divergent viral lineages at various scales of relatedness. With this analysis, we determine a region inside the receptor-binding domain with putative sites under positive selection interspersed among highly conserved sites, which are implicated in structural stability of the viral spike protein and its union with human receptor hACE2. Next, to gain further insights into factors associated with coronaviruses recognition of the human host receptor, we performed modeling studies of five different coronaviruses and their potential binding to hACE2. Modeling results indicate that interfering with the salt bridges at hot spot 353 could be an effective strategy for inhibiting binding, and hence for the prevention of coronavirus infections. We also propose that a glycine residue at the receptor binding domain of the spike glycoprotein can have a critical role in permitting bat variants of the coronaviruses to infect human cells.

scholarly journals A Structural Landscape of Neutralizing Antibodies Against SARS-CoV-2 Receptor Binding Domain

2021 ◽  
Vol 12 ◽  
Author(s):  
Ling Niu ◽  
Kathryn N. Wittrock ◽  
Gage C. Clabaugh ◽  
Vikram Srivastava ◽  
Michael W. Cho
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Critical Role ◽  
Binding Domain ◽  
The Novel ◽  
Receptor Binding Domain ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Virus Life Cycle ◽  
Novel Coronavirus

SARS-CoV-2, the novel coronavirus responsible for the ongoing COVID-19 pandemic, has been spreading rampantly. The global scientific community has responded rapidly to understand immune correlates of protection to develop vaccines and immunotherapeutics against the virus. The major goal of this mini review is to summarize current understanding of the structural landscape of neutralizing antibodies (nAbs) that target the receptor binding domain (RBD) of viral spike (S) glycoprotein. The RBD plays a critical role in the very first step of the virus life cycle. Better understanding of where and how nAbs bind the RBD should enable identification of sites of vulnerability and facilitate better vaccine design and formulation of immunotherapeutics. Towards this goal, we compiled 38 RBD-binding nAbs with known structures. Review of these nAb structures showed that (1) nAbs can be divided into five general clusters, (2) there are distinct non-neutralizing faces on the RBD, and (3) maximum of potentially four nAbs could bind the RBD simultaneously. Since most of these nAbs were isolated from virus-infected patients, additional analyses of vaccine-induced nAbs could facilitate development of improved vaccines.

scholarly journals Enhancement of SARS-CoV-2 Receptor Binding Domain -CR3022 Human Antibody Binding Affinity via in Silico Engineering Approach

2020 ◽  
Author(s):  
Fateme Sefid ◽  
Zahra Payandeh ◽  
Ghasem Azamirad ◽  
Behzad Mansoori ◽  
Behzad Baradaran ◽  
...  
Keyword(s):  
Amino Acids ◽  
Binding Affinity ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Affinity Maturation ◽  
Binding Domain ◽  
Human Antibody ◽  
Receptor Binding Domain ◽  
Receptor Binding Site ◽  
Specificity And Sensitivity

Abstract Background: The nCoV-2019 is a cause of COVID-19 disease. The surface spike glycoprotein (S), which is necessary for virus entry through the intervention of the host receptor and it mediates virus-host membrane fusion, is the primary coronavirus antigen (Ag). The angiotensin-converting enzyme 2 (ACE2) is reported to be the effective human receptor for SARS-CoVs 2. ACE2 receptor can be prevented by neutralizing antibodies (nAbs) such as CR3022 targeting the virus receptor-binding site. Considering the importance of computational docking, and affinity maturation we aimed to find the important amino acids of the CR3022 antibody (Ab). These amino acids were then replaced by other amino acids to improve Ab-binding affinity to a receptor-binding domain (RBD) of the 2019-nCoV spike protein. Finally, we measured the binding affinity of Ab variants to the Ag. Result: Our findings disclosed that several variant mutations could successfully improve the characteristics of the Ab binding compared to the normal antibodies. Conclusion: The modified antibodies may be possible candidates for stronger affinity binding to Ags which in turn can affect the specificity and sensitivity of antibodies.

scholarly journals Rapid production of SARS-CoV-2 receptor binding domain (RBD) and spike specific monoclonal antibody CR3022 in Nicotiana benthamiana

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kaewta Rattanapisit ◽  
Balamurugan Shanmugaraj ◽  
Suwimon Manopwisedjaroen ◽  
Priyo Budi Purwono ◽  
Konlavat Siriwattananon ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Nicotiana Benthamiana ◽  
Specific Binding ◽  
Expression System ◽  
Disease Diagnosis ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Global Public Health

Abstract Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the ongoing global outbreak of coronavirus disease (COVID-19) which is a significant threat to global public health. The rapid spread of COVID-19 necessitates the development of cost-effective technology platforms for the production of vaccines, drugs, and protein reagents for appropriate disease diagnosis and treatment. In this study, we explored the possibility of producing the receptor binding domain (RBD) of SARS-CoV-2 and an anti-SARS-CoV monoclonal antibody (mAb) CR3022 in Nicotiana benthamiana. Both RBD and mAb CR3022 were transiently produced with the highest expression level of 8 μg/g and 130 μg/g leaf fresh weight respectively at 3 days post-infiltration. The plant-produced RBD exhibited specific binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2). Furthermore, the plant-produced mAb CR3022 binds to SARS-CoV-2, but fails to neutralize the virus in vitro. This is the first report showing the production of anti-SARS-CoV-2 RBD and mAb CR3022 in plants. Overall these findings provide a proof-of-concept for using plants as an expression system for the production of SARS-CoV-2 antigens and antibodies or similar other diagnostic reagents against SARS-CoV-2 rapidly, especially during epidemic or pandemic situation.

scholarly journals Identification of a Receptor-Binding Domain of the Spike Glycoprotein of Human Coronavirus HCoV-229E

2003 ◽  
Vol 77 (4) ◽  
pp. 2530-2538 ◽  
Author(s):  
Aurelio Bonavia ◽  
Bruce D. Zelus ◽  
David E. Wentworth ◽  
Pierre J. Talbot ◽  
Kathryn V. Holmes
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Protein A ◽  
Binding Domain ◽  
Expression Vectors ◽  
Receptor Binding Domain ◽  
3T3 Cells ◽  
Spike Glycoprotein ◽  
Human Coronavirus ◽  
S Proteins

ABSTRACT Human coronavirus HCoV-229E uses human aminopeptidase N (hAPN) as its receptor (C. L. Yeager et al., Nature 357:420-422, 1992). To identify the receptor-binding domain of the viral spike glycoprotein (S), we expressed soluble truncated histidine-tagged S glycoproteins by using baculovirus expression vectors. Truncated S proteins purified by nickel affinity chromatography were shown to be glycosylated and to react with polyclonal anti-HCoV-229E antibodies and monoclonal antibodies to the viral S protein. A truncated protein (S547) that contains the N-terminal 547 amino acids bound to 3T3 mouse cells that express hAPN but not to mouse 3T3 cells transfected with empty vector. Binding of S547 to hAPN was blocked by an anti-hAPN monoclonal antibody that inhibits binding of virus to hAPN and blocks virus infection of human cells and was also blocked by polyclonal anti-HCoV-229E antibody. S proteins that contain the N-terminal 268 or 417 amino acids did not bind to hAPN-3T3 cells. Antibody to the region from amino acid 417 to the C terminus of S blocked binding of S547 to hAPN-3T3 cells. Thus, the data suggest that the domain of the spike protein between amino acids 417 and 547 is required for the binding of HCoV-229E to its hAPN receptor.

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