scholarly journals Comparative Immunomodulatory Evaluation of the Receptor Binding Domain of the SARS-CoV-2 Spike Protein; a Potential Vaccine Candidate Which Imparts Potent Humoral and Th1 Type Immune Response in a Mouse Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Tripti Shrivastava ◽  
Balwant Singh ◽  
Zaigham Abbas Rizvi ◽  
Rohit Verma ◽  
Sandeep Goswami ◽  
...  
Keyword(s):  
Immune Response ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Vaccine Candidate ◽  
Unmet Need ◽  
Binding Domain ◽  
Spike Protein ◽  
Cell Immune Response ◽  
Receptor Binding Domain

The newly emerged novel coronavirus, SARS-CoV-2, the causative agent of COVID-19 has proven to be a threat to the human race globally, thus, vaccine development against SARS-CoV-2 is an unmet need driving mass vaccination efforts. The receptor binding domain of the spike protein of this coronavirus has multiple neutralizing epitopes and is associated with viral entry. Here we have designed and characterized the SARS-CoV-2 spike protein fragment 330-526 as receptor binding domain 330-526 (RBD330-526) with two native glycosylation sites (N331 and N343); as a potential subunit vaccine candidate. We initially characterized RBD330-526 biochemically and investigated its thermal stability, humoral and T cell immune response of various RBD protein formulations (with or without adjuvant) to evaluate the inherent immunogenicity and immunomodulatory effect. Our result showed that the purified RBD immunogen is stable up to 72 h, without any apparent loss in affinity or specificity of interaction with the ACE2 receptor. Upon immunization in mice, RBD generates a high titer humoral response, elevated IFN-γ producing CD4+ cells, cytotoxic T cells, and robust neutralizing antibodies against live SARS-CoV-2 virus. Our results collectively support the potential of RBD330-526 as a promising vaccine candidate against SARS-CoV-2.

scholarly journals Stereotypic neutralizing VH antibodies against SARS-CoV-2 spike protein receptor binding domain in COVID-19 patients and healthy individuals

2021 ◽  
pp. eabd6990
Author(s):  
Sang Il Kim ◽  
Jinsung Noh ◽  
Sujeong Kim ◽  
Younggeun Choi ◽  
Duck Kyun Yoo ◽  
...  
Keyword(s):  
B Cells ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
De Novo ◽  
Binding Domain ◽  
Host Cells ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Healthy Individuals

Stereotypic antibody clonotypes exist in healthy individuals and may provide protective immunity against viral infections by neutralization. We observed that 13 out of 17 patients with COVID-19 had stereotypic variable heavy chain (VH) antibody clonotypes directed against the receptor-binding domain (RBD) of SARS-CoV-2 spike protein. These antibody clonotypes were comprised of immunoglobulin heavy variable (IGHV)3-53 or IGHV3-66 and immunoglobulin heavy joining (IGHJ)6 genes. These clonotypes included IgM, IgG3, IgG1, IgA1, IgG2, and IgA2 subtypes and had minimal somatic mutations, which suggested swift class switching after SARS-CoV-2 infection. The different immunoglobulin heavy variable chains were paired with diverse light chains resulting in binding to the RBD of SARS-CoV-2 spike protein. Human antibodies specific for the RBD can neutralize SARS-CoV-2 by inhibiting entry into host cells. We observed that one of these stereotypic neutralizing antibodies could inhibit viral replication in vitro using a clinical isolate of SARS-CoV-2. We also found that these VH clonotypes existed in six out of 10 healthy individuals, with IgM isotypes predominating. These findings suggest that stereotypic clonotypes can develop de novo from naïve B cells and not from memory B cells established from prior exposure to similar viruses. The expeditious and stereotypic expansion of these clonotypes may have occurred in patients infected with SARS-CoV-2 because they were already present.

Construction and immunogenic studies of a mFc fusion receptor binding domain (RBD) of spike protein as a subunit vaccine against SARS-CoV-2 infection

2020 ◽  
Vol 56 (61) ◽  
pp. 8683-8686 ◽  
Author(s):  
Xiaoxiao Qi ◽  
Bixia Ke ◽  
Qian Feng ◽  
Deying Yang ◽  
Qinghai Lian ◽  
...  
Keyword(s):  
Amino Acid ◽  
Fusion Protein ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Subunit Vaccine ◽  
Binding Domain ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Humoral And Cellular Immunity ◽  
A Subunit

Herein, we report that a recombinant fusion protein, containing a 457 amino acid SARS-CoV-2 receptor binding domain and a mouse IgG1 Fc domain, could induce highly potent neutralizing antibodies and stimulate humoral and cellular immunity in mice.

scholarly journals Recombinant Mycobacterium paragordonae Expressing SARS-CoV-2 Receptor-Binding Domain as a Vaccine Candidate Against SARS-CoV-2 Infections

2021 ◽  
Vol 12 ◽  
Author(s):  
Byoung-Jun Kim ◽  
Hyein Jeong ◽  
Hyejun Seo ◽  
Mi-Hyun Lee ◽  
Hyun Mu Shin ◽  
...  
Keyword(s):  
Immune Response ◽  
Single Dose ◽  
Immune Responses ◽  
Receptor Binding ◽  
Humoral Immune Response ◽  
Vaccine Candidate ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Live Virus ◽  
Humoral Immune

At present, concerns that the recent global emergence of SARS-CoV-2 variants could compromise the current vaccines have been raised, highlighting the urgent demand for new vaccines capable of eliciting T cell-mediated immune responses, as well as B cell-mediated neutralizing antibody production. In this study, we developed a novel recombinant Mycobacterium paragordonae expressing the SARS-CoV-2 receptor-binding domain (RBD) (rMpg-RBD-7) that is capable of eliciting RBD-specific immune responses in vaccinated mice. The potential use of rMpg-RBD-7 as a vaccine for SARS-CoV-2 infections was evaluated in in vivo using mouse models of two different modules, one for single-dose vaccination and the other for two-dose vaccination. In a single-dose vaccination model, we found that rMpg-RBD-7 versus a heat-killed strain could exert an enhanced cell-mediated immune (CMI) response, as well as a humoral immune response capable of neutralizing the RBD and ACE2 interaction. In a two-dose vaccination model, rMpg-RBD-7 in a two-dose vaccination could also exert a stronger CMI and humoral immune response to neutralize SARS-CoV-2 infections in pseudoviral or live virus infection systems, compared to single dose vaccinations of rMpg-RBD or two-dose RBD protein immunization. In conclusion, our data showed that rMpg-RBD-7 can lead to an enhanced CMI response and humoral immune responses in mice vaccinated with both single- or two-dose vaccination, highlighting its feasibility as a novel vaccine candidate for SARS-CoV-2. To the best of our knowledge, this study is the first in which mycobacteria is used as a delivery system for a SARS-CoV-2 vaccine.

scholarly journals Development of spike receptor-binding domain nanoparticle as a vaccine candidate against SARS-CoV-2 infection in ferrets

2021 ◽  
Author(s):  
Young-Il Kim ◽  
Dokyun Kim ◽  
Kwang-Min Yu ◽  
Hogyu David Seo ◽  
Shin-Ae Lee ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Clinical Symptoms ◽  
Binding Domain ◽  
Host Cells ◽  
Antigen Delivery ◽  
Receptor Binding Domain ◽  
Protein Vaccine

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a causative agent of COVID-19 pandemic, enters host cells via the interaction of its Receptor-Binding Domain (RBD) of Spike protein with host Angiotensin-Converting Enzyme 2 (ACE2). Therefore, RBD is a promising vaccine target to induce protective immunity against SARS-CoV-2 infection. In this study, we report the development of RBD protein-based vaccine candidate against SARS-CoV-2 using self-assembling H. pylori-bullfrog ferritin nanoparticles as an antigen delivery. RBD-ferritin protein purified from mammalian cells efficiently assembled into 24-mer nanoparticles. 16-20 months-old ferrets were vaccinated with RBD-ferritin nanoparticles (RBD-nanoparticles) by intramuscular or intranasal inoculation. All vaccinated ferrets with RBD-nanoparticles produced potent neutralizing antibodies against SARS-CoV-2. Strikingly, vaccinated ferrets demonstrated efficient protection from SARS-CoV-2 challenge, showing no fever, body weight loss and clinical symptoms. Furthermore, vaccinated ferrets showed rapid clearance of infectious viruses in nasal washes and lungs as well as viral RNA in respiratory organs. This study demonstrates the Spike RBD-nanoparticle as an effective protein vaccine candidate against SARS-CoV-2.

scholarly journals Yeast-expressed Recombinant SARS-CoV-2 Receptor Binding Domain, RBD203-N1 as a COVID-19 Protein Vaccine Candidate

2021 ◽  
Author(s):  
Wen-Hsiang Chen ◽  
Jeroen Pollet ◽  
Ulrich Strych ◽  
Jungsoon Lee ◽  
Zhuyun Liu ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Total Yield ◽  
Development Program ◽  
Exchange Chromatography ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Protein Vaccine ◽  
Protein Subunit

Background: SARS-CoV-2 protein subunit vaccines are being evaluated by multiple manufacturers to fill the need for low-cost, easy to scale, safe, and effective COVID-19 vaccines for global access. Vaccine candidates relying on the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein have been the focus of our development program. In this paper, we report on the generation of the RBD203-N1 yeast expression construct, which produces a recombinant protein that when formulated with alum and the TLR-9 agonist, CpG1826 elicits a robust immune response and protection in mice. Method: The RBD203-N1 antigen was expressed in the yeast Pichia pastoris X33. After fermentation at the 5 L scale, the protein was purified by hydrophobic interaction chromatography followed by anion exchange chromatography. The purified protein was characterized biophysically and biochemically, and after its formulation, the immunogenicity and efficacy were evaluated in mice. Results, Conclusions, and Significance: The RBD203-N1 production process yielded 492.9 ± 3.0 mg/L of protein in the fermentation supernatant. A two-step purification process produced a >96% pure protein with a recovery rate of 55 ± 3% (total yield of purified protein: 270.5 ± 13.2 mg/L fermentation supernatant). The protein was characterized as a homogeneous monomer with well-defined secondary structure, thermally stable, antigenic, and when adjuvanted on alum and CpG, it was immunogenic and induced robust levels of neutralizing antibodies against SARS-CoV-2 pseudovirus. These characteristics show that this vaccine candidate is well suited for technology transfer with feasibility of its transition into the clinic to evaluate its immunogenicity and safety in humans.

scholarly journals Protein Footprinting, Conformational Dynamics and Interface-Adjacent Neutralization ‘Hotspots’ in the SARS-CoV-2 Spike Protein Receptor Binding Domain / Human ACE2 Interaction

2020 ◽  
Author(s):  
Dominic Narang ◽  
Matthew Balmer ◽  
D. Andrew James ◽  
Derek Wilson
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Conformational Dynamics ◽  
Binding Domain ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Angiotensin Converting Enzyme 2 ◽  
Additional Information ◽  
Protein Receptor ◽  
Hdx Ms

This study provides an HDX-MS based analysis of the interaction between the SARS-CoV-2 spike protein and the human Angiotensin Converting Enzyme 2. <div><br></div><div>- The data agree exactly with the X-ray co-crystal structure of this complex, but provide additional information based on shifts in dynamics that are observed just outside the interface. </div><div><br></div><div>- These dynamic changes occur specifically in regions that are the primary targets of neutralizing antibodies that target spike protein, suggesting that the neutralization mechanism may result from suppression of dynamic shifts in the spike Receptor Binding Domain (RBD) that are necessary for favorable binding thermodynamics in the spike / ACE2 interaction.</div>

scholarly journals The receptor binding domain of SARS-CoV-2 spike is the key target of neutralizing antibody in human polyclonal sera

2020 ◽  
Author(s):  
Tara L. Steffen ◽  
E. Taylor Stone ◽  
Mariah Hassert ◽  
Elizabeth Geerling ◽  
Brian T. Grimberg ◽  
...  
Keyword(s):  
Antibody Response ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Binding Domain ◽  
Antigenic Determinants ◽  
Receptor Binding Domain ◽  
Neutralization Capacity

AbstractNatural infection of SARS-CoV-2 in humans leads to the development of a strong neutralizing antibody response, however the immunodominant targets of the polyclonal neutralizing antibody response are still unknown. Here, we functionally define the role SARS-CoV-2 spike plays as a target of the human neutralizing antibody response. In this study, we identify the spike protein subunits that contain antigenic determinants and examine the neutralization capacity of polyclonal sera from a cohort of patients that tested qRT-PCR-positive for SARS-CoV-2. Using an ELISA format, we assessed binding of human sera to spike subunit 1 (S1), spike subunit 2 (S2) and the receptor binding domain (RBD) of spike. To functionally identify the key target of neutralizing antibody, we depleted sera of subunit-specific antibodies to determine the contribution of these individual subunits to the antigen-specific neutralizing antibody response. We show that epitopes within RBD are the target of a majority of the neutralizing antibodies in the human polyclonal antibody response. These data provide critical information for vaccine development and development of sensitive and specific serological testing.

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