scholarly journals Intranasal inhibitor blocks Omicron and other variants of SARS-CoV-2

2021 ◽  
Author(s):  
Anna R Mäkelä ◽  
Hasan Uğurlu ◽  
Liina Hannula ◽  
Petja Salminen ◽  
Ravi Kant ◽  
...  
Keyword(s):  
Animal Models ◽  
Molecular Basis ◽  
Neutralizing Antibodies ◽  
Intranasal Administration ◽  
Inhibitory Action ◽  
Large Scale ◽  
Antibody Fragments ◽  
Protective Measure ◽  
Receptor Binding Domain ◽  
Target Epitope

The emergence of the SARS-CoV-2 Omicron variant capable of escaping neutralizing antibodies emphasizes the need for prophylactic strategies to complement vaccination in fighting the COVID-19 pandemic. Nasal epithelium is rich in the ACE2 receptor and important for SARS-CoV-2 transmission by supporting early viral replication before seeding to the lung. Intranasal administration of SARS-CoV-2 neutralizing antibodies or antibody fragments has shown encouraging potential as a protective measure in animal models. However, there remains a need for SARS-CoV-2 blocking agents that are more economical to produce in large scale, while less vulnerable to mutational variation in the neutralization epitopes of the viral Spike glycoprotein. Here we describe TriSb92, a highly manufacturable trimeric human nephrocystin SH3 domain-derived antibody mimetic targeted against a conserved region in the receptor-binding domain of the Spike. TriSb92 potently neutralizes SARS-CoV-2 and its variants of concern, including Delta and Omicron. Intranasal administration of a modest dose of TriSb92 (5 or 50 micrograms) as early as eight hours before the challenge with SARS-CoV-2 B.1.351 efficiently protected mice from infection. The target epitope of TriSb92 was defined by cryo-EM, which revealed triggering of a conformational shift in the Spike trimer rather than competition for ACE2 binding as the molecular basis of its strong inhibitory action. Our results highlight the potential of intranasal inhibitors in protecting susceptible individuals from SARS-CoV-2 infection, and describe a novel type of inhibitor that could be of use in addressing the challenge posed by the Omicron variant.

scholarly journals Intranasal inhibitor blocks omicron and other variants of SARS-CoV-2

2021 ◽  
Author(s):  
Kalle Saksela ◽  
Anna Mäkelä ◽  
Hasan Ugurlu ◽  
Liina Hanula ◽  
Petja Salminen ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Molecular Basis ◽  
Neutralizing Antibodies ◽  
Intranasal Administration ◽  
Inhibitory Action ◽  
Large Scale ◽  
Antibody Fragments ◽  
Protective Measure ◽  
Receptor Binding Domain ◽  
Target Epitope

Abstract The emergence of the SARS-CoV-2 Omicron variant capable of escaping neutralizing antibodies emphasizes the need for prophylactic strategies to complement vaccination in fighting the COVID-19 pandemic. Nasal epithelium is rich in the ACE2 receptor and important for SARS-CoV-2 transmission by supporting early viral replication before seeding to the lung1. Intranasal administration of SARS-CoV-2 neutralizing antibodies or antibody fragments has shown encouraging potential as a protective measure in animal models2-5. However, there remains a need for SARS-CoV-2 blocking agents that are more economical to produce in large scale, while less vulnerable to mutational variation in the neutralization epitopes of the viral Spike glycoprotein. Here we describe TriSb92, a highly manufacturable trimeric human nephrocystin SH3 domain-derived antibody mimetic targeted against a conserved region in the receptor-binding domain of the Spike. TriSb92 potently neutralizes SARS-CoV-2 and its variants of concern, including Delta and Omicron. Intranasal administration of a modest dose of TriSb92 (5 or 50 micrograms) as early as eight hours before the challenge with SARS-CoV-2 B.1.351 efficiently protected mice from infection. The target epitope of TriSb92 was defined by cryo-EM, which revealed triggering of a conformational shift in the Spike trimer rather than competition for ACE2 binding as the molecular basis of its strong inhibitory action. Our results highlight the potential of intranasal inhibitors in protecting susceptible individuals from SARS-CoV-2 infection, and describe a novel type of inhibitor that could be of use in addressing the challenge posed by the Omicron variant.

scholarly journals Structural and functional comparison of SARS-CoV-2-spike receptor binding domain produced in Pichia pastoris and mammalian cells

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Keyword(s):  
Pichia Pastoris ◽  
Receptor Binding ◽  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Large Scale ◽  
Binding Domain ◽  
Size Exclusion ◽  
Scale Production ◽  
Receptor Binding Domain ◽  
Serological Tests

AbstractThe yeast Pichia pastoris is a cost-effective and easily scalable system for recombinant protein production. In this work we compared the conformation of the receptor binding domain (RBD) from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Spike protein expressed in P. pastoris and in the well established HEK-293T mammalian cell system. RBD obtained from both yeast and mammalian cells was properly folded, as indicated by UV-absorption, circular dichroism and tryptophan fluorescence. They also had similar stability, as indicated by temperature-induced unfolding (observed Tm were 50 °C and 52 °C for RBD produced in P. pastoris and HEK-293T cells, respectively). Moreover, the stability of both variants was similarly reduced when the ionic strength was increased, in agreement with a computational analysis predicting that a set of ionic interactions may stabilize RBD structure. Further characterization by high-performance liquid chromatography, size-exclusion chromatography and mass spectrometry revealed a higher heterogeneity of RBD expressed in P. pastoris relative to that produced in HEK-293T cells, which disappeared after enzymatic removal of glycans. The production of RBD in P. pastoris was scaled-up in a bioreactor, with yields above 45 mg/L of 90% pure protein, thus potentially allowing large scale immunizations to produce neutralizing antibodies, as well as the large scale production of serological tests for SARS-CoV-2.

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

2021 ◽  
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.

scholarly journals An Adenovirus Vector Expressing FMDV RNA Polymerase Combined with a Chimeric VLP Harboring a Neutralizing Epitope as a Prime Boost Strategy to Induce FMDV-Specific Humoral and Cellular Responses

2021 ◽  
Vol 14 (7) ◽  
pp. 675
Author(s):  
Giselle Rangel ◽  
Verónica Martín ◽  
Juan Bárcena ◽  
Esther Blanco ◽  
Alí Alejo
Keyword(s):  
T Cell ◽  
Neutralizing Antibodies ◽  
Large Scale ◽  
Recombinant Adenovirus ◽  
Protective Efficacy ◽  
Vaccination Strategy ◽  
Adenovirus Vector ◽  
T Cell Responses ◽  
Protective Measure ◽  
Cell Responses

Foot and mouth disease is a highly contagious disease affecting cattle, sheep, and swine among other cloven-hoofed animals that imposes serious economic burden by its direct effects on farm productivity as well as on commerce of farmed produce. Vaccination using inactivated viral strains of the different serotypes is an effective protective measure, but has several drawbacks including a lack of cross protection and the perils associated with the large-scale growth of infectious virus. We have previously developed chimeric virus-like particles (VLPs) bearing an FMDV epitope which induced strong specific humoral responses in vaccinated pigs but conferred only partial protection against homologous challenge. While this and other FMD vaccines under development mostly rely on the induction of neutralizing responses, it is thought that induction of specific T-cell responses might improve both cross protective efficacy as well as duration of immunity. Therefore, we here describe the development of a recombinant adenovirus expressing the highly conserved nonstructural FMDV 3D protein as well as its capacity to induce specific T-cell responses in a murine model. We further describe the generation of an FMDV serotype C-specific chimeric VLP and analyze the immunogenicity of two different prime-boost strategies combining both elements in mice. This combination can effectively induce both humoral and cellular FMDV-specific responses eliciting high titers of ELISA and neutralizing antibodies anti-FMDV as well as a high frequency of IFNγ-secreting cells. These results provide the basis for further testing of this anti FMD vaccination strategy in cattle or pig, two of the most relevant natural host of this pathogen.

scholarly journals A lipid nanoparticle RBD-hFc mRNA vaccine protects hACE2 transgenic mice against lethal SARS-CoV-2 infection

2021 ◽  
Author(s):  
Uri Elia ◽  
Shahar Rotem ◽  
Erez Bar-Haim ◽  
Srinivas Ramishetti ◽  
Gonna Somu Naidu ◽  
...  
Keyword(s):  
Animal Models ◽  
Viral Replication ◽  
Neutralizing Antibodies ◽  
Protective Efficacy ◽  
Lethal Dose ◽  
Humoral Response ◽  
Receptor Binding Domain ◽  
Efficacy Data ◽  
Phase 3 ◽  
Mild Disease

The current global COVID-19 pandemic led to an unprecedented effort to develop effective vaccines against SARS-CoV-2. mRNA vaccines were developed very rapidly during the last year, and became the leading immunization platform against the virus, with highly promising phase-3 results and remarkable efficacy data. Since most animal models are not susceptible to SARS CoV-2 infection, pre-clinical studies are often limited to infection-prone animals such as hamsters and non-human primates. In these animal models, SARS-CoV-2 infection results in viral replication and a mild disease disease. Therefore, the protective efficacy of the vaccine in these animals is commonly evaluated by its ability to elicit immunologic responses, diminish viral replication and prevent weight loss. Our lab recently reported the design of a SARS-CoV-2 human Fc-conjugated receptor-binding domain (RBD-hFc) mRNA vaccine delivered via lipid nanoparticles (LNPs). These experiments demonstrated the development of a robust and specific immunologic response in RBD-hFc mRNA- vaccinated BALB/c mice. In the current study, we evaluated the protective effect of this RBD-hFc mRNA vaccine by employing the K18-hACE2 mouse model. We report that administration of RBD-hFc mRNA vaccine to K18-hACE2 mice led to a robust humoral response comprised of both binding and neutralizing antibodies. In accordance with the recorded immunologic immune response, 70% of vaccinated mice were protected against a lethal dose (3000 plaque forming units) of SARS-CoV-2, while all control animals succumbed to infection. To the best of our knowledge, this is the first non-replicating mRNA vaccine study reporting protection of K18-hACE2 against a lethal SARS-CoV-2 infection.

scholarly journals Cryo-electron microscopy structures of the N501Y SARS-CoV-2 spike protein in complex with ACE2 and 2 potent neutralizing antibodies

PLoS Biology ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. e3001237
Author(s):  
Xing Zhu ◽  
Dhiraj Mannar ◽  
Shanti S. Srivastava ◽  
Alison M. Berezuk ◽  
Jean-Philippe Demers ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutralizing Antibodies ◽  
Structural Changes ◽  
Neutralizing Antibody ◽  
Antibody Fragments ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Structural Explanation ◽  
Binding Interface ◽  
Cryo Electron Microscopy

The recently reported “UK variant” (B.1.1.7) 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-electron microscopy (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. This additional interaction provides a structural explanation for the increased ACE2 affinity of the N501Y mutant, and likely contributes to 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 2 representative potent neutralizing antibody fragments.

scholarly journals Structural and Functional Comparison of SARS-CoV-2-Spike Receptor Binding Domain Produced in Pichia pastoris and Mammalian Cells

2020 ◽  
Author(s):  
◽  
Claudia R. Arbeitman ◽  
Gabriela Auge ◽  
Matías Blaustein ◽  
Luis Bredeston ◽  
...  
Keyword(s):  
Pichia Pastoris ◽  
Receptor Binding ◽  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Large Scale ◽  
Binding Domain ◽  
Size Exclusion ◽  
Scale Production ◽  
Receptor Binding Domain ◽  
Serological Tests

AbstractThe yeast Pichia pastoris is a cost-effective and easily scalable system for recombinant protein production. In this work we compared the conformation of the receptor binding domain (RBD) from SARS-CoV-2 Spike protein expressed in P. pastoris and in the well established HEK-293T mammalian cell system. RBD obtained from both yeast and mammalian cells was properly folded, as indicated by UV-absorption, circular dichroism and tryptophan fluorescence. They also had similar stability, as indicated by temperature-induced unfolding (observed Tm were 50 °C and 52 °C for RBD produced in P. pastoris and HEK-293T cells, respectively). Moreover, the stability of both variants was similarly reduced when the ionic strength was increased, in agreement with a computational analysis predicting that a set of ionic interactions may stabilize RBD structure. Further characterization by HPLC, size-exclusion chromatography and mass spectrometry revealed a higher heterogeneity of RBD expressed in P. pastoris relative to that produced in HEK-293T cells, which disappeared after enzymatic removal of glycans. The production of RBD in P. pastoris was scaled-up in a bioreactor, with yields above 45 mg/L of 90% pure protein, thus potentially allowing large scale immunizations to produce neutralizing antibodies, as well as the large scale production of serological tests for 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.

scholarly journals mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection

Science ◽  
2021 ◽  
pp. eabg9175 ◽  
Author(s):  
Leonidas Stamatatos ◽  
Julie Czartoski ◽  
Yu-Hsin Wan ◽  
Leah J. Homad ◽  
Vanessa Rubin ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Previous Infection

Emerging SARS-CoV-2 variants have raised concerns about resistance to neutralizing antibodies elicited by previous infection or vaccination. We examined whether sera from recovered and naïve donors collected prior to, and following immunizations with existing mRNA vaccines, could neutralize the Wuhan-Hu-1 and B.1.351 variants. Pre-vaccination sera from recovered donors neutralized Wuhan-Hu-1 and sporadically neutralized B.1.351, but a single immunization boosted neutralizing titers against all variants and SARS-CoV-1 by up to 1000-fold. Neutralization was due to antibodies targeting the receptor binding domain and was not boosted by a second immunization. Immunization of naïve donors also elicited cross-neutralizing responses, but at lower titers. Our study highlights the importance of vaccinating both uninfected and previously infected persons to elicit cross-variant neutralizing antibodies.

scholarly journals Rapid seroconversion and persistent functional IgG antibodies in severe COVID-19 patients correlates with an IL-12p70 and IL-33 signature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ariel Munitz ◽  
L. Edry-Botzer ◽  
M. Itan ◽  
R. Tur-Kaspa ◽  
D. Dicker ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Neutralizing Antibodies ◽  
Host Response ◽  
Humoral Response ◽  
Rapid Onset ◽  
Response Analysis ◽  
Receptor Binding Domain ◽  
Igg Antibodies ◽  
Viral Receptor ◽  
Iga Antibodies

AbstractDespite ongoing efforts to characterize the host response toward SARS-CoV-2, a major gap in our knowledge still exists regarding the magnitude and duration of the humoral response. Analysis of the antibody response in mild versus moderate/severe patients, using our new developed quantitative electrochemiluminescent assay for detecting IgM/IgA/IgG antibodies toward SARS-CoV-2 antigens, revealed a rapid onset of IgG/IgA antibodies, specifically in moderate/severe patients. IgM antibodies against the viral receptor binding domain, but not against nucleocapsid protein, were detected at early stages of the disease. Furthermore, we observed a marked reduction in IgM/IgA antibodies over-time. Adapting our assay for ACE2 binding-competition, demonstrated that the presence of potentially neutralizing antibodies is corelated with IgG/IgA. Finally, analysis of the cytokine profile in COVID-19 patients revealed unique correlation of an IL-12p70/IL33 and IgG seroconversion, which correlated with disease severity. In summary, our comprehensive analysis has major implications on the understanding and monitoring of SARS-CoV-2 infections.

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