scholarly journals Potent Neutralization Antibodies Induced by a Recombinant Trimeric Spike Protein Vaccine Candidate Containing PIKA Adjuvant for COVID-19

Vaccines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 296
Author(s):  
Jiao Tong ◽  
Chenxi Zhu ◽  
Hanyu Lai ◽  
Chunchao Feng ◽  
Dapeng Zhou
Keyword(s):  
Monoclonal Antibodies ◽  
Vaccine Candidate ◽  
Spike Protein ◽  
Heptad Repeat ◽  
Peptide Array ◽  
Receptor Binding Domain ◽  
Protein Vaccine ◽  
Direct Binding ◽  
Linear Epitopes ◽  
Potent Neutralization

The structures of immunogens that elicit the most potent neutralization antibodies to prevent COVID-19 infection are still under investigation. In this study, we tested the efficacy of a recombinant trimeric Spike protein containing polyI:C (PIKA) adjuvant in mice immunized by a 0–7–14 day schedule. The results showed that a Spike protein-specific antibody was induced at Day 21 with titer of above 50,000 on average, as measured by direct binding. The neutralizing titer was above 1000 on average, as determined by a pseudo-virus using monoclonal antibodies (40592-MM57 and 40591-MM43) with IC50 at 1 μg/mL as standards. The protein/peptide array-identified receptor-binding domain (RBD) was considered as immunodominant. No linear epitopes were found in the RBD, although several linear epitopes were found in the C-terminal domain right after the RBD and heptad repeat regions. Our study supports the efficacy of a recombinant trimeric Spike protein vaccine candidate for COVID-19 that is safe and ready for storage and distribution in developing countries.

scholarly journals Potent neutralization antibodies induced by a recombinant trimeric Spike protein vaccine candidate containing PIKA adjuvant for COVID-19

2021 ◽  
Author(s):  
Jiao Tong ◽  
Chenxi Zhu ◽  
Hanyu Lai ◽  
Chunchao Feng ◽  
Dapeng Zhou
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Natural Infection ◽  
Spike Protein ◽  
Heptad Repeat ◽  
Protein Vaccine ◽  
Direct Binding ◽  
Linear Epitopes ◽  
Virus System ◽  
Potent Neutralization

AbstractNeutralizing antibodies are critical to prevent corona virus infection. The structures of immunogens to elicit most potent neutralization antibodies are still under investigation. Here we tested the immunogenicity of the trimeric, full length Spike protein with 2 proline mutations to preserve its prefusion conformation. Recombinant trimeric Spike protein expressed by CHO cells was used with polyI:C (PIKA) adjuvant to immunize mice by 0-7-14 day schedule. The results showed that Spike-specific antibody was induced at day 21 with titer of more than 50,000 in average as measured by direct binding to Spike protein. The titer of neutralization reached more than 1000 in average when tested by a pseudo-virus system, using monoclonal antibodies (40592-MM57 and 40591-MM43) with neutralizing IC50 at 1 μg/ml as standards. Protein/peptide array showed that the antibodies induced by trimeric S protein vaccine bind similarly to natural infection with the receptor binding domain (RBD) as major immunodominant region. No linear epitopes were found in RBD, although several linear epitopes were found in C-terminal domain right after RBD, and heptad repeat regions. Our study supports the efficacy of recombinant trimeric Spike protein vaccine candidate for COVID-19, with excellent safety and readiness for storage and distribution in developing countries.

scholarly journals ANALYSIS OF IMMUNE ESCAPE VARIANTS FROM ANTIBODY-BASED THERAPEUTICS AGAINST COVID-19.

2021 ◽  
Author(s):  
Daniele Focosi ◽  
Fabrizio Maggi ◽  
Massimo Franchini ◽  
Scott McConnell ◽  
Arturo Casadevall
Keyword(s):  
Public Health ◽  
Monoclonal Antibodies ◽  
Immune Evasion ◽  
Immune Escape ◽  
Selective Pressure ◽  
Neutralizing Antibody ◽  
Spike Protein ◽  
Single Amino Acid ◽  
Receptor Binding Domain ◽  
Amino Acid Mutations

Accelerated SARS-CoV-2 evolution under selective pressure by massive deployment of neutralizing antibody-based therapeutics is a concern with potentially severe implications for public health. We review here reports of documented immune escape after treatment with monoclonal antibodies and COVID19 convalescent plasma (CCP). While the former is mainly associated with specific single amino acid mutations at residues within the receptor-binding domain (e.g., E484K/Q, Q493R, and S494P), the few cases of immune evasion after CCP were associated with recurrent deletions within the N-terminal domain of Spike protein (e.g, delHV69-70, delLGVY141-144 and delAL243-244). Continuous genomic monitoring of non-responders is needed to better understand immune escape frequencies and fitness of emerging variants.

scholarly journals Adaptation of SARS-CoV-2 in BALB/c mice for testing vaccine efficacy

Science ◽  
2020 ◽  
pp. eabc4730 ◽  
Author(s):  
Hongjing Gu ◽  
Qi Chen ◽  
Guan Yang ◽  
Lei He ◽  
Hang Fan ◽  
...  
Keyword(s):  
Vaccine Candidate ◽  
Inflammatory Responses ◽  
Protective Efficacy ◽  
Small Animal ◽  
Spike Protein ◽  
Mouse Lung ◽  
Receptor Binding Domain ◽  
Intranasal Inoculation ◽  
Adaptive Mutations ◽  
Small Animal Models

The ongoing COVID-19 pandemic has prioritized the development of small animal models for SARS-CoV-2. Herein, we adapted a clinical isolate of SARS-CoV-2 by serial passaging in the respiratory tract of aged BALB/c mice. The resulting mouse-adapted strain at passage 6 (termed MASCp6) showed increased infectivity in mouse lung, and led to interstitial pneumonia and inflammatory responses in both young and aged mice following intranasal inoculation. Deep sequencing revealed a panel of adaptive mutations potentially associated with the increased virulence. In particular, the N501Y mutation is located at the receptor binding domain (RBD) of the spike protein. The protective efficacy of a recombinant RBD vaccine candidate was validated using this model. Thus, this mouse-adapted strain and associated challenge model should be of value in evaluating vaccines and antivirals against SARS-CoV-2.

scholarly journals Monoclonal Antibodies Targeting the HR2 Domain and the Region Immediately Upstream of the HR2 of the S Protein Neutralize In Vitro Infection of Severe Acute Respiratory Syndrome Coronavirus

2006 ◽  
Vol 80 (2) ◽  
pp. 941-950 ◽  
Author(s):  
Kuo-Ming Lip ◽  
Shuo Shen ◽  
Xiaoming Yang ◽  
Choong-Tat Keng ◽  
Aihua Zhang ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Polyclonal Antibodies ◽  
Heptad Repeat ◽  
Functional Domain ◽  
Protein Fragment ◽  
S Protein ◽  
Linear Epitopes ◽  
Respiratory Coronavirus ◽  
Neutralizing Epitopes

ABSTRACT We have previously shown that an Escherichia coli-expressed, denatured spike (S) protein fragment of the severe acute respiratory coronavirus, containing residues 1029 to 1192 which include the heptad repeat 2 (HR2) domain, was able to induce neutralizing polyclonal antibodies (C. T. Keng, A. Zhang, S. Shen, K. M. Lip, B. C. Fielding, T. H. Tan, C. F. Chou, C. B. Loh, S. Wang, J. Fu, X. Yang, S. G. Lim, W. Hong, and Y. J. Tan, J. Virol. 79:3289-3296, 2005). In this study, monoclonal antibodies (MAbs) were raised against this fragment to identify the linear neutralizing epitopes in the functional domain and to investigate the mechanisms involved in neutralization. Eighteen hybridomas secreting the S protein-specific MAbs were obtained. Binding sites of these MAbs were mapped to four linear epitopes. Two of them were located within the HR2 region and two immediately upstream of the HR2 domain. MAbs targeting these epitopes showed in vitro neutralizing activities and were able to inhibit cell-cell membrane fusion. These results provide evidence of novel neutralizing epitopes that are located in the HR2 domain and the spacer region immediately upstream of the HR2 of the S protein.

scholarly journals Neutralizing Monoclonal Antibodies That Target the Spike Receptor Binding Domain Confer Fc Receptor-Independent Protection against SARS-CoV-2 Infection in Syrian Hamsters

mBio ◽  
2021 ◽  
Author(s):  
Wen Su ◽  
Sin Fun Sia ◽  
Aaron J. Schmitz ◽  
Traci L. Bricker ◽  
Tyler N. Starr ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Severe Acute Respiratory Syndrome ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Fc Receptor ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Syrian Hamsters ◽  
Convalescent Phase ◽  
Main Target

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein is the main target for neutralizing antibodies. These antibodies can be elicited through immunization or passively transferred as therapeutics in the form of convalescent-phase sera or monoclonal antibodies (MAbs).

scholarly journals SARS-CoV-2 variants resist antibody neutralization and broaden host ACE2 usage

2021 ◽  
Author(s):  
Ruoke Wang ◽  
Qi Zhang ◽  
Jiwan Ge ◽  
Wenlin Ren ◽  
Rui Zhang ◽  
...  
Keyword(s):  
South Africa ◽  
Monoclonal Antibodies ◽  
Molecular Basis ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Antibody Neutralization ◽  
Vaccine Protection ◽  
Antigenic Sites ◽  
Global Pandemic ◽  
Crystal Structural

AbstractNew SARS-CoV-2 variants continue to emerge from the current global pandemic, some of which can replicate faster and with greater transmissibility and pathogenicity. In particular, UK501Y.V1 identified in UK, SA501Y.V2 in South Africa, and BR501Y.V3 in Brazil are raising serious concerns as they spread quickly and contain spike protein mutations that may facilitate escape from current antibody therapies and vaccine protection. Here, we constructed a panel of 28 SARS-CoV-2 pseudoviruses bearing single or combined mutations found in the spike protein of these three variants, as well as additional nine mutations that within or close by the major antigenic sites in the spike protein identified in the GISAID database. These pseudoviruses were tested against a panel of monoclonal antibodies (mAbs), including some approved for emergency use to treat SARS-CoV-2 infection, and convalescent patient plasma collected early in the pandemic. SA501Y.V2 pseudovirus was the most resistant, in magnitude and breadth, against mAbs and convalescent plasma, followed by BR501Y.V3, and then UK501Y.V1. This resistance hierarchy corresponds with Y144del and 242-244del mutations in the N-terminal domain as well as K417N/T, E484K and N501Y mutations in the receptor binding domain (RBD). Crystal structural analysis of RBD carrying triple K417N-E484K-N501Y mutations found in SA501Y.V2 bound with mAb P2C-1F11 revealed a molecular basis for antibody neutralization and escape. SA501Y.V2 and BR501Y.V3 also acquired substantial ability to use mouse and mink ACE2 for entry. Taken together, our results clearly demonstrate major antigenic shifts and potentially broadening the host range of SA501Y.V2 and BR501Y.V3, which pose serious challenges to our current antibody therapies and vaccine protection.

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 Structures of SARS-CoV-2 B.1.351 neutralizing antibodies provide insights into cocktail design against concerning variants

2021 ◽  
Author(s):  
Shuo Du ◽  
Pulan Liu ◽  
Zhiying Zhang ◽  
Tianhe Xiao ◽  
Ayijiang Yasimayi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibodies ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Antibody Responses ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Humoral Antibody ◽  
Cryo Electron Microscopy ◽  
Antibody Cocktail

The spread of the SARS-CoV-2 variants could seriously dampen the global effort to tackle the COVID-19 pandemic. Recently, we investigated the humoral antibody responses of SARS-CoV-2 convalescent patients and vaccinees towards circulating variants, and identified a panel of monoclonal antibodies (mAbs) that could efficiently neutralize the B.1.351 (Beta) variant. Here we investigate how these mAbs target the B.1.351 spike protein using cryo-electron microscopy. In particular, we show that two superpotent mAbs, BD-812 and BD-836, have non-overlapping epitopes on the receptor-binding domain (RBD) of spike. Both block the interaction between RBD and the ACE2 receptor; and importantly, both remain fully efficacious towards the B.1.617.1 (Kappa) and B.1.617.2 (Delta) variants. The BD-812/BD-836 pair could thus serve as an ideal antibody cocktail against the SARS-CoV-2 VOCs.

scholarly journals Decreased neutralization of SARS-CoV-2 global variants by therapeutic anti-spike protein monoclonal antibodies

2021 ◽  
Author(s):  
Takuya Tada ◽  
Belinda M. Dcosta ◽  
Hao Zhou ◽  
Ada Vaill ◽  
Wes Kazmierski ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Receptor Binding ◽  
Binding Domain ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Neutralization Activity ◽  
Protein Mutations ◽  
Spike Proteins

AbstractMonoclonal antibodies against the SARS-CoV-2 spike protein, notably, those developed by Regeneron Pharmaceuticals and Eli Lilly and Company have proven to provide protection against severe COVID-19. The emergence of SARS-CoV-2 variants with heavily mutated spike proteins raises the concern that the therapy could become less effective if any of the mutations disrupt epitopes engaged by the antibodies. In this study, we tested monoclonal antibodies REGN10933 and REGN10987 that are used in combination, for their ability to neutralize SARS-CoV-2 variants B.1.1.7, B.1.351, mink cluster 5 and COH.20G/677H. We report that REGN10987 maintains most of its neutralization activity against viruses with B.1.1.7, B.1.351 and mink cluster 5 spike proteins but that REGN10933 has lost activity against B.1.351 and mink cluster 5. The failure of REGN10933 to neutralize B.1.351 is caused by the K417N and E484K mutations in the receptor binding domain; the failure to neutralize the mink cluster 5 spike protein is caused by the Y453F mutation. The REGN10933 and REGN10987 combination was 9.1-fold less potent on B.1.351 and 16.2-fold less potent on mink cluster 5, raising concerns of reduced efficacy in the treatment of patients infected with variant viruses. The results suggest that there is a need to develop additional monoclonal antibodies that are not affected by the current spike protein mutations.

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