A Truncated Receptor-Binding Domain of MERS-CoV Spike Protein Potently Inhibits MERS-CoV Infection and Induces Strong Neutralizing Antibody Responses: Implication for Developing Therapeutics and Vaccines

Middle East respiratory syndrome coronavirus (MERS-CoV) has continuously posed a threat to public health worldwide, yet no therapeutics or vaccines are currently available to prevent or treat MERS-CoV infection. We previously identified a fusion inhibitory peptide (HR2P-M2) targeting the MERS-CoV S2 protein HR1 domain and a highly potent neutralizing monoclonal antibody (m336) specific to the S1 spike protein receptor-binding domain (RBD). However, m336 was found to have reduced efficacy against MERS-CoV strains with mutations in RBD, and HR2P-M2 showed low potency, thus limiting the clinical application of each when administered separately. However, we herein report that the combination of m336 and HR2P-M2 exhibited potent synergism in inhibiting MERS-CoV S protein-mediated cell–cell fusion and infection by MERS-CoV pseudoviruses with or without mutations in the RBD, resulting in the enhancement of antiviral activity in contrast to either one administered alone. Thus, this combinatorial strategy could be used in clinics for the urgent treatment of MERS-CoV-infected patients.

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High resolution linear epitope mapping of the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 mRNA vaccine recipients.

10.1101/2021.07.03.21259953 ◽

2021 ◽

Author(s):

Yuko Nitahara ◽

Yu Nakagama ◽

Natsuko Kaku ◽

Katherine Candray ◽

Yu Michimuko ◽

...

Keyword(s):

High Resolution ◽

Receptor Binding ◽

Messenger Rna ◽

Natural Infection ◽

Neutralizing Antibody ◽

Binding Domain ◽

Spike Protein ◽

Linear Epitope ◽

Receptor Binding Domain ◽

Population Immunity

The prompt rollout of the coronavirus disease (COVID-19) messenger RNA (mRNA) vaccine facilitated population immunity, which shall become more dominant than natural infection-induced immunity. At the beginning of the vaccine era, the initial epitope profile in naive individuals will be the first step to build an optimal host defense system towards vaccine-based population immunity. In this study, the high-resolution linear epitope profiles between Pfizer-BioNTech COVID-19 mRNA vaccine recipients and COVID-19 patients were delineated by using microarrays mapped with overlapping peptides of the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. The vaccine-induced antibodies targeting RBD had broader distribution across the RBD than that induced by the natural infection. The relatively lower neutralizing antibody titers observed in vaccine-induced sera could attribute to less efficient epitope selection and maturation of the vaccine-induced humoral immunity compared to the infection-induced. Furthermore, additional mutation panel assays showed that the vaccine-induced rich epitope variety targeting the RBD may aid antibodies to escape rapid viral evolution, which could grant an advantage to the vaccine immunity.

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Polymersomes decorated with SARS-CoV-2 spike protein receptor binding domain elicit robust humoral and cellular immunity

10.1101/2021.04.08.438884 ◽

2021 ◽

Author(s):

Lisa R Volpatti ◽

Rachel P Wallace ◽

Shijie Cao ◽

Michal Raczy ◽

Ruyi Wang ◽

...

Keyword(s):

T Cell ◽

Antibody Response ◽

Receptor Binding ◽

Neutralizing Antibody ◽

Binding Domain ◽

Spike Protein ◽

Receptor Binding Domain ◽

Vaccination Site ◽

Monophosphoryl Lipid A ◽

Protein Receptor

A diverse portfolio of SARS-CoV-2 vaccine candidates is needed to combat the evolving COVID-19 pandemic. Here, we developed a subunit nanovaccine by conjugating SARS-CoV-2 Spike protein receptor binding domain (RBD) to the surface of oxidation-sensitive polymersomes. We evaluated the humoral and cellular responses of mice immunized with these surface-decorated polymersomes (RBDsurf) compared to RBD-encapsulated polymersomes (RBDencap) and unformulated RBD (RBDfree), using monophosphoryl lipid A-encapsulated polymersomes (MPLA PS) as an adjuvant. While all three groups produced high titers of RBD-specific IgG, only RBDsurf elicited a neutralizing antibody response to SARS-CoV-2 comparable to that of human convalescent plasma. Moreover, RBDsurf was the only group to significantly increase the proportion of RBD-specific germinal center B cells in the vaccination-site draining lymph nodes. Both RBDsurf and RBDencap drove similarly robust CD4+ and CD8+ T cell responses that produced multiple Th1-type cytokines. We conclude that multivalent surface display of Spike RBD on polymersomes promotes a potent neutralizing antibody response to SARS-CoV-2, while both antigen formulations promote robust T cell immunity.

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Coronavirus-Specific Antibody Cross Reactivity in Rhesus Macaques Following SARS-CoV-2 Vaccination and Infection

Journal of Virology ◽

10.1128/jvi.00117-21 ◽

2021 ◽

Author(s):

Catherine Jacob-Dolan ◽

Jared Feldman ◽

Katherine McMahan ◽

Jingyou Yu ◽

Roland Zahn ◽

...

Keyword(s):

Receptor Binding ◽

Specific Antibody ◽

Rhesus Macaques ◽

Rapid Development ◽

Neutralizing Antibody ◽

Cross Reactivity ◽

Antibody Responses ◽

Spike Protein ◽

Receptor Binding Domain ◽

Before And After

Vaccines are being rapidly developed with the goal of ending the SARS-CoV-2 pandemic. However, the extent to which SARS-CoV-2 vaccination induces serum responses that cross-react with other coronaviruses remains poorly studied. Here we define serum profiles in rhesus macaques after vaccination with DNA or Ad26 based vaccines expressing SARS-CoV-2 Spike protein followed by SARS-CoV-2 challenge, or SARS-CoV-2 infection alone. Analysis of serum responses showed robust reactivity to the SARS-CoV-2 full-length Spike protein and receptor binding domain (RBD), both included in the vaccine. However, serum cross-reactivity to the closely related sarbecovirus SARS-CoV-1 Spike and RBD, was reduced. Reactivity was also measured to the distantly related common cold alpha-coronavirus, 229E and NL63, and beta-coronavirus, OC43 and HKU1, Spike proteins. Using SARS-COV-2 and SARS-CoV-1 lentivirus based pseudoviruses, we show that neutralizing antibody responses were predominantly SARS-CoV-2 specific. These data define patterns of cross-reactive binding and neutralizing serum responses induced by SARS-CoV-2 infection and vaccination in rhesus macaques. Our observations have important implications for understanding polyclonal responses to SARS-CoV-2 Spike, which will facilitate future CoV vaccine assessment and development. Importance The rapid development and deployment of SARS-CoV-2 vaccines has been unprecedented. In this study, we explore the cross-reactivity of SARS-CoV-2 specific antibody responses to other coronaviruses. By analyzing responses from NHPs both before and after immunization with DNA or Ad26 vectored vaccines, we find patterns of cross reactivity that mirror those induced by SARS-CoV-2 infection. These data highlight the similarities between infection and vaccine induced humoral immunity for SARS-CoV-2 and cross-reactivity of these responses to other CoVs.

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XAV-19, a Swine Glyco-Humanized Polyclonal Antibody Against SARS-CoV-2 Spike Receptor-Binding Domain, Targets Multiple Epitopes and Broadly Neutralizes Variants

Frontiers in Immunology ◽

10.3389/fimmu.2021.761250 ◽

2021 ◽

Vol 12 ◽

Author(s):

Bernard Vanhove ◽

Stéphane Marot ◽

Ray T. So ◽

Benjamin Gaborit ◽

Gwénaëlle Evanno ◽

...

Keyword(s):

South African ◽

Receptor Binding ◽

Polyclonal Antibodies ◽

Neutralizing Antibody ◽

Binding Domain ◽

Spike Protein ◽

Receptor Binding Domain ◽

Live Virus ◽

Angiotensin Converting Enzyme 2 ◽

The United Kingdom

Amino acid substitutions and deletions in the Spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants can reduce the effectiveness of monoclonal antibodies (mAbs). In contrast, heterologous polyclonal antibodies raised against S protein, through the recognition of multiple target epitopes, have the potential to maintain neutralization capacities. XAV-19 is a swine glyco-humanized polyclonal neutralizing antibody raised against the receptor binding domain (RBD) of the Wuhan-Hu-1 Spike protein of SARS-CoV-2. XAV-19 target epitopes were found distributed all over the RBD and particularly cover the receptor binding motives (RBMs), in direct contact sites with the angiotensin converting enzyme-2 (ACE-2). Therefore, in Spike/ACE-2 interaction assays, XAV-19 showed potent neutralization capacities of the original Wuhan Spike and of the United Kingdom (Alpha/B.1.1.7) and South African (Beta/B.1.351) variants. These results were confirmed by cytopathogenic assays using Vero E6 and live virus variants including the Brazil (Gamma/P.1) and the Indian (Delta/B.1.617.2) variants. In a selective pressure study on Vero E6 cells conducted over 1 month, no mutation was associated with the addition of increasing doses of XAV-19. The potential to reduce viral load in lungs was confirmed in a human ACE-2 transduced mouse model. XAV-19 is currently evaluated in patients hospitalized for COVID-19-induced moderate pneumonia in phase 2a-2b (NCT04453384) where safety was already demonstrated and in an ongoing 2/3 trial (NCT04928430) to evaluate the efficacy and safety of XAV-19 in patients with moderate-to-severe COVID-19. Owing to its polyclonal nature and its glyco-humanization, XAV-19 may provide a novel safe and effective therapeutic tool to mitigate the severity of coronavirus disease 2019 (COVID-19) including the different variants of concern identified so far.

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A Novel Neutralizing Antibody Targeting Receptor Binding Domain of SARS-CoV-2

10.21203/rs.3.rs-59639/v1 ◽

2020 ◽

Author(s):

Soo-Young Lee ◽

Cheolmin Kim ◽

Dong-Kyun Ryu ◽

Jihun Lee ◽

Young-Il Kim ◽

...

Keyword(s):

Receptor Binding ◽

Human Monoclonal Antibody ◽

Substantial Reduction ◽

Neutralizing Antibody ◽

Binding Domain ◽

Spike Protein ◽

Enhancement Effect ◽

Therapeutic Effects ◽

Receptor Binding Domain ◽

Protein Variant

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the current COVID-19 global pandemic. Vaccines and therapeutics are urgently needed for this highly transmissible virus. In this study, we screened human monoclonal antibodies (mAbs) targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein from an antibody library constructed from peripheral blood mononuclear cells of a COVID-19 convalescent patient. A potent neutralizing antibody, termed CT-P59, was identified and found to be effective against various SARS-CoV-2 isolates including the D614G spike protein variant without antibody-dependent enhancement effect. Complex crystal structure of CT-P59 Fab/SARS-CoV-2 RBD showed that CT-P59 blocks interaction regions of SARS-CoV-2 RBD for its cellular receptor, angiotensin converting enzyme 2 (ACE2). The binding orientation of CT-P59 is notably different from the previously reported neutralizing mAbs targeting SARS-CoV-2 RBD suggesting that CT-P59 can be a novel binder to SARS-CoV-2 RBD. Therapeutic effects of CT-P59 were evaluated in three animal models (ferret, hamster, and rhesus monkey), and a substantial reduction in viral titre along with alleviation of clinical symptoms was observed. These findings suggest that the human monoclonal antibody, CT-P59, is a promising therapeutic candidate for treatment of COVID-19.

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Binding and Neutralizing Antibody Responses to SARS-CoV-2 in Infants and Young Children Exceed Those in Adults

10.1101/2021.12.20.21268034 ◽

2021 ◽

Author(s):

Ruth A. Karron ◽

Maria Garcia Quesada ◽

Elizabeth A. Schappell ◽

Stephen D. Schmidt ◽

Maria Deloria Knoll ◽

...

Keyword(s):

Young Children ◽

Immune Responses ◽

Receptor Binding ◽

Neutralizing Antibody ◽

Binding Domain ◽

Antibody Responses ◽

Receptor Binding Domain ◽

Binding Antibody ◽

Infants And Young Children

SARS-CoV-2 infections are frequently milder in children than adults, suggesting that immune responses may vary with age. However, information is limited regarding SARS-CoV-2 immune responses in young children. We compared Receptor Binding Domain binding antibody (RBDAb) and SARS-CoV-2 neutralizing antibody (neutAb) in children aged 0-4 years, 5-17 years, and in adults aged 18-62 years in a SARS-CoV-2 household study. Among 55 participants seropositive at enrollment, children aged 0-4 years had >10-fold higher RBDAb titers than adults (373 vs.35, P<0.0001), and the highest RBDAb titers in 11/12 households with seropositive children and adults. Children aged 0-4 years had 2-fold higher neutAb than adults, resulting in higher binding to neutralizing (B/N)Ab ratios compared to adults (1.9 vs. 0.4 for ID50, P=0.0002). Findings suggest that young children mount robust antibody responses to SARS-CoV-2 following community infections. Additionally, these results support using neutAb to measure the immunogenicity of COVID-19 vaccines in children aged 0-4 years.

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Cryo-EM Structures of the N501Y SARS-CoV-2 Spike Protein in Complex with ACE2 and Two Potent Neutralizing Antibodies

10.1101/2021.01.11.426269 ◽

2021 ◽

Cited By ~ 1

Author(s):

Xing Zhu ◽

Dhiraj Mannar ◽

Shanti S. Srivastava ◽

Alison M. Berezuk ◽

Jean-Philippe Demers ◽

...

Keyword(s):

Receptor Binding ◽

Neutralizing Antibodies ◽

Structural Changes ◽

Neutralizing Antibody ◽

Antibody Fragments ◽

Binding Domain ◽

Spike Protein ◽

Receptor Binding Domain ◽

Binding Interface ◽

Short Summary

AbstractThe recently reported “UK variant” of SARS-CoV-2 is thought to be more infectious than previously circulating strains as a result of several changes, including the N501Y mutation. We present a 2.9-Å resolution cryo-EM structure of the complex between the ACE2 receptor and N501Y spike protein ectodomains that shows Y501 inserted into a cavity at the binding interface near Y41 of ACE2. The additional interactions result in increased affinity of ACE2 for the N501Y mutant, accounting for its increased infectivity. However, this mutation does not result in large structural changes, enabling important neutralization epitopes to be retained in the spike receptor binding domain. We confirmed this through biophysical assays and by determining cryo-EM structures of spike protein ectodomains bound to two representative potent neutralizing antibody fragments.Short summaryThe N501Y mutation found in the coronavirus UK variant increases infectivity but some neutralizing antibodies can still bind.

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