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1.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-318387

ABSTRACT

Potently neutralizing SARS-CoV-2 antibodies often target the receptor binding site (RBS) of spike protein but the variability of RBS epitopes hampers broad neutralization of different clades of coronaviruses and emerging drifted viruses. Here, we identified a human RBS antibody that potently neutralizes SARS-CoV and SARS-CoV-2 variants that belong to clade 1 SARS-related coronavirus. X-ray crystallography revealed coordinated recognition by the heavy chain to conserved sites and the light chain to RBS, allowing for the mimicry of ACE2 binding mode. The minimum footprints in the hypervariable region of RBS contributed to the breadth of neutralization, and the activity was further enhanced by IgG3 switching. Eventually, the coordinated binding resulted in broad neutralization of SARS-CoV and emerging SARS-CoV-2 variants of concern. Furthermore, therapeutic treatment in a hamster model provided protection at low dosage. The structural basis for broadly neutralizing activity informs the design of broad spectrum of therapeutics and vaccines.Funding: This work was supported by Japan Agency for Medical Research and Development grant JP19fk0108111 (TH, YT), JP20fk0108298 (TK, TH, KM, YT), JP20am0101093 (KM), JP20ae0101047 (KM), JP20fk0108251 (HS), and JP20am0101124 (YK), by Ministry of Education, Culture, Sports, Science and Technology grant JPMXS0420100119 (KM) and 20H05773 (TH), by The Naito Foundation (TH), and by Joint Usage/Research Center program of Institute for Frontier Life and Medical Sciences, Kyoto University (KM).Conflict of Interest: AS is an employee of Shionogi & Co., Ltd. MO is a CEO, employee, and shareholder of Trans Chromosomics, Inc. These authors acknowledge a potential conflict of interest and attest that the work contained in this report is free of any bias that might be associated with the commercial goals of the company. TO, YA, MO, TH, KM, and YT declare that an intellectual property application has been filed using the data presented in this paper. The other authors declare that they have no competing interests.Ethical Approval: Animal procedures were approved by the Animal Ethics Committee of the National Institute of Infectious Diseases, Japan, and performed in accordance with the guidelines of the Institutional Animal Care and Use Committee. In vitro escape mutation screening experiments for SARSCoV-2 were performed at the Biosafety Level-3 facility of the Research Center for ZoonosisControl, Hokkaido University, and the National Institute of Infectious Diseases following the institutional guidelines.

2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-313038

ABSTRACT

Effective vaccines are essential for the control of the COVID-19 pandemic. Currently-developed vaccines inducing SARS-CoV-2 spike (S) antigen-specific neutralizing antibodies (NAbs) are effective, but the appearance of NAb-resistant S variant viruses is of great concern. A vaccine inducing S-independent or NAb-independent SARS-CoV-2 control may contribute to containment of these variants. Here, we investigated the efficacy of an intranasal vaccine expressing viral non-S antigens against intranasal SARS-CoV-2 challenge in cynomolgus macaques. Nine vaccinated macaques exhibited significantly reduced viral load in nasopharyngeal swabs on day 2 post-challenge compared to nine unvaccinated controls. The viral control in the absence of SARS-CoV-2-specific NAbs was significantly correlated with vaccine-induced viral antigen-specific CD8+ T-cell responses. Our results indicate that CD8+ T-cell induction by intranasal vaccination can result in NAb-independent control of SARS-CoV-2 infection, highlighting a potential of vaccine-induced CD8+ T-cell responses to contribute to COVID-19 containment.Funding: This work was supported by Japan Agency for Medical Research and Development (AMED [JP19fk0108104 to A.K.-T. and JP20nk0101601, JP20jm0110012, JP21fk0410035, JP21fk0108125, and JP21jk0210002 to T.M.]) and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan (JSPS Grants-in-Aid for Scientific Research [21H02745 to T.M.]).Declaration of Interests: H.I., K.K., R.S., and T.M are the inventors on Patent Cooperation Treaty (PCT) application for SeV-NME vaccine. Authors have no other conflicts of interest to declare.Ethics Approval Statement: Approval by the Committee on the Ethics of Animal Experiments in NIID (permission number: 520001) under the guidelines for animal experiments in accordance with the Guidelines for Proper Conduct of Animal Experiments established by the Science Council of Japan.

3.
Cell Rep Med ; 3(2): 100520, 2022 02 15.
Article in English | MEDLINE | ID: covidwho-1633496

ABSTRACT

Effective vaccines are essential for the control of the coronavirus disease 2019 (COVID-19) pandemic. Currently developed vaccines inducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S)-antigen-specific neutralizing antibodies (NAbs) are effective, but the appearance of NAb-resistant S variant viruses is of great concern. A vaccine inducing S-independent or NAb-independent SARS-CoV-2 control may contribute to containment of these variants. Here, we investigate the efficacy of an intranasal vaccine expressing viral non-S antigens against intranasal SARS-CoV-2 challenge in cynomolgus macaques. Seven vaccinated macaques exhibit significantly reduced viral load in nasopharyngeal swabs on day 2 post-challenge compared with nine unvaccinated controls. The viral control in the absence of SARS-CoV-2-specific NAbs is significantly correlated with vaccine-induced, viral-antigen-specific CD8+ T cell responses. Our results indicate that CD8+ T cell induction by intranasal vaccination can result in NAb-independent control of SARS-CoV-2 infection, highlighting a potential of vaccine-induced CD8+ T cell responses to contribute to COVID-19 containment.


Subject(s)
Administration, Intranasal/methods , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , CD8-Positive T-Lymphocytes/immunology , COVID-19 Vaccines/administration & dosage , COVID-19/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Vaccination/methods , Animals , COVID-19/epidemiology , COVID-19/virology , COVID-19 Vaccines/immunology , Chlorocebus aethiops , Coronavirus Envelope Proteins/immunology , Coronavirus M Proteins/immunology , Coronavirus Nucleocapsid Proteins/immunology , Disease Models, Animal , Female , Macaca fascicularis , Male , Pandemics/prevention & control , Phosphoproteins/immunology , Spike Glycoprotein, Coronavirus/immunology , Treatment Outcome , Vero Cells , Viral Load
4.
Sci Adv ; 8(1): eabh3827, 2022 Jan 07.
Article in English | MEDLINE | ID: covidwho-1612934

ABSTRACT

One safety concern during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine development has been the vaccine-associated enhanced disease, which is characterized by eosinophilic immunopathology and T helper cell type 2 (TH2)­biased immune responses with insufficient neutralizing antibodies. In this study, we established a lethal animal model using BALB/c mice and a mouse-passaged isolate (QHmusX) from a European lineage of SARS-CoV-2. The QHmusX strain induced acute respiratory illness, associated with diffuse alveolar damage and pulmonary edema, in TH2-prone adult BALB/c mice, but not in young mice or TH1-prone C57BL/6 mice. We also showed that immunization of adult BALB/c mice with recombinant spike protein without appropriate adjuvant caused eosinophilic immunopathology with TH2-shifted immune response and insufficient neutralizing antibodies after QHmusX infection. This lethal mouse model is useful for evaluating vaccine-associated enhanced respiratory disease during SARS-CoV-2 infection and may provide new insights into the disease pathogenesis of SARS-CoV-2.

5.
PLoS Pathog ; 17(7): e1009668, 2021 07.
Article in English | MEDLINE | ID: covidwho-1388961

ABSTRACT

SARS-CoV-2 infection presents clinical manifestations ranging from asymptomatic to fatal respiratory failure. Despite the induction of functional SARS-CoV-2-specific CD8+ T-cell responses in convalescent individuals, the role of virus-specific CD8+ T-cell responses in the control of SARS-CoV-2 replication remains unknown. In the present study, we show that subacute SARS-CoV-2 replication can be controlled in the absence of CD8+ T cells in cynomolgus macaques. Eight macaques were intranasally inoculated with 105 or 106 TCID50 of SARS-CoV-2, and three of the eight macaques were treated with a monoclonal anti-CD8 antibody on days 5 and 7 post-infection. In these three macaques, CD8+ T cells were undetectable on day 7 and thereafter, while virus-specific CD8+ T-cell responses were induced in the remaining five untreated animals. Viral RNA was detected in nasopharyngeal swabs for 10-17 days post-infection in all macaques, and the kinetics of viral RNA levels in pharyngeal swabs and plasma neutralizing antibody titers were comparable between the anti-CD8 antibody treated and untreated animals. SARS-CoV-2 RNA was detected in the pharyngeal mucosa and/or retropharyngeal lymph node obtained at necropsy on day 21 in two of the untreated group but undetectable in all macaques treated with anti-CD8 antibody. CD8+ T-cell responses may contribute to viral control in SARS-CoV-2 infection, but our results indicate possible containment of subacute viral replication in the absence of CD8+ T cells, implying that CD8+ T-cell dysfunction may not solely lead to viral control failure.


Subject(s)
CD8-Positive T-Lymphocytes/immunology , COVID-19/veterinary , Macaca fascicularis/immunology , Macaca fascicularis/virology , Monkey Diseases/immunology , Monkey Diseases/virology , SARS-CoV-2/immunology , SARS-CoV-2/physiology , Animals , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/immunology , COVID-19/virology , Disease Models, Animal , Female , Humans , Kinetics , Lymphocyte Depletion/veterinary , Male , RNA, Viral/genetics , RNA, Viral/metabolism , SARS-CoV-2/genetics , Virus Replication/immunology
6.
Immunity ; 54(10): 2385-2398.e10, 2021 10 12.
Article in English | MEDLINE | ID: covidwho-1370548

ABSTRACT

Potent neutralizing SARS-CoV-2 antibodies often target the spike protein receptor-binding site (RBS), but the variability of RBS epitopes hampers broad neutralization of multiple sarbecoviruses and drifted viruses. Here, using humanized mice, we identified an RBS antibody with a germline VH gene that potently neutralized SARS-related coronaviruses, including SARS-CoV and SARS-CoV-2 variants. X-ray crystallography revealed coordinated recognition by the heavy chain of non-RBS conserved sites and the light chain of RBS with a binding angle mimicking the angiotensin-converting enzyme 2 (ACE2) receptor. The minimum footprints in the hypervariable region of RBS contributed to the breadth of neutralization, which was enhanced by immunoglobulin G3 (IgG3) class switching. The coordinated binding resulted in broad neutralization of SARS-CoV and emerging SARS-CoV-2 variants of concern. Low-dose therapeutic antibody treatment in hamsters reduced the virus titers and morbidity during SARS-CoV-2 challenge. The structural basis for broad neutralizing activity may inform the design of a broad spectrum of therapeutics and vaccines.


Subject(s)
Broadly Neutralizing Antibodies/immunology , Cross Reactions/immunology , SARS-CoV-2/immunology , Animals , Betacoronavirus/immunology , Binding Sites, Antibody , Broadly Neutralizing Antibodies/chemistry , Broadly Neutralizing Antibodies/therapeutic use , COVID-19/prevention & control , COVID-19/therapy , COVID-19/virology , Cricetinae , Humans , Immunoglobulin Class Switching , Immunoglobulin Fab Fragments/chemistry , Immunoglobulin Fab Fragments/metabolism , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Mice , Protein Domains , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
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