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1.
Viruses ; 12(7)2020 07 07.
Article in English | MEDLINE | ID: covidwho-639283

ABSTRACT

Standard precautions to minimize the risk of SARS-CoV-2 transmission implies that infected cell cultures and clinical specimens may undergo some sort of inactivation to reduce or abolish infectivity. We evaluated three heat inactivation protocols (56 °C-30 min, 60 °C-60 min and 92 °C-15 min) on SARS-CoV-2 using (i) infected cell culture supernatant, (ii) virus-spiked human sera (iii) and nasopharyngeal samples according to the recommendations of the European norm NF EN 14476-A2. Regardless of the protocol and the type of samples, a 4 Log10 TCID50 reduction was observed. However, samples containing viral loads > 6 Log10 TCID50 were still infectious after 56 °C-30 min and 60 °C-60 min, although infectivity was < 10 TCID50. The protocols 56 °C-30 min and 60 °C-60 min had little influence on the RNA copies detection, whereas 92 °C-15 min drastically reduced the limit of detection, which suggests that this protocol should be avoided for inactivation ahead of molecular diagnostics. Lastly, 56 °C-30 min treatment of serum specimens had a negligible influence on the results of IgG detection using a commercial ELISA test, whereas a drastic decrease in neutralizing titers was observed.


Subject(s)
Betacoronavirus , Containment of Biohazards/methods , Coronavirus Infections/virology , Pneumonia, Viral/virology , Serologic Tests/methods , Virus Inactivation , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Containment of Biohazards/standards , Coronavirus Infections/diagnosis , Coronavirus Infections/prevention & control , Enzyme-Linked Immunosorbent Assay , Hot Temperature , Humans , Neutralization Tests , Pandemics/prevention & control , Pneumonia, Viral/diagnosis , Pneumonia, Viral/prevention & control , Serologic Tests/standards
2.
Nat Commun ; 11(1): 4303, 2020 08 27.
Article in English | MEDLINE | ID: covidwho-733523

ABSTRACT

The novel highly transmissible human coronavirus SARS-CoV-2 is the causative agent of the COVID-19 pandemic. Thus far, there is no approved therapeutic drug specifically targeting this emerging virus. Here we report the isolation and characterization of a panel of human neutralizing monoclonal antibodies targeting the SARS-CoV-2 receptor binding domain (RBD). These antibodies were selected from a phage display library constructed using peripheral circulatory lymphocytes collected from patients at the acute phase of the disease. These neutralizing antibodies are shown to recognize distinct epitopes on the viral spike RBD. A subset of the antibodies exert their inhibitory activity by abrogating binding of the RBD to the human ACE2 receptor. The human monoclonal antibodies described here represent a promising basis for the design of efficient combined post-exposure therapy for SARS-CoV-2 infection.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Antibodies, Viral/immunology , Antibodies, Viral/metabolism , Betacoronavirus/metabolism , Chlorocebus aethiops , Epitope Mapping , Epitopes , Humans , Peptide Library , Peptidyl-Dipeptidase A/metabolism , Protein Binding , Protein Interaction Domains and Motifs , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
4.
Sci Rep ; 10(1): 14004, 2020 08 19.
Article in English | MEDLINE | ID: covidwho-724698

ABSTRACT

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a novel evolutionary divergent RNA virus, is responsible for the present devastating COVID-19 pandemic. To explore the genomic signatures, we comprehensively analyzed 2,492 complete and/or near-complete genome sequences of SARS-CoV-2 strains reported from across the globe to the GISAID database up to 30 March 2020. Genome-wide annotations revealed 1,516 nucleotide-level variations at different positions throughout the entire genome of SARS-CoV-2. Moreover, nucleotide (nt) deletion analysis found twelve deletion sites throughout the genome other than previously reported deletions at coding sequence of the ORF8 (open reading frame), spike, and ORF7a proteins, specifically in polyprotein ORF1ab (n = 9), ORF10 (n = 1), and 3´-UTR (n = 2). Evidence from the systematic gene-level mutational and protein profile analyses revealed a large number of amino acid (aa) substitutions (n = 744), demonstrating the viral proteins heterogeneous. Notably, residues of receptor-binding domain (RBD) showing crucial interactions with angiotensin-converting enzyme 2 (ACE2) and cross-reacting neutralizing antibody were found to be conserved among the analyzed virus strains, except for replacement of lysine with arginine at 378th position of the cryptic epitope of a Shanghai isolate, hCoV-19/Shanghai/SH0007/2020 (EPI_ISL_416320). Furthermore, our results of the preliminary epidemiological data on SARS-CoV-2 infections revealed that frequency of aa mutations were relatively higher in the SARS-CoV-2 genome sequences of Europe (43.07%) followed by Asia (38.09%), and North America (29.64%) while case fatality rates remained higher in the European temperate countries, such as Italy, Spain, Netherlands, France, England and Belgium. Thus, the present method of genome annotation employed at this early pandemic stage could be a promising tool for monitoring and tracking the continuously evolving pandemic situation, the associated genetic variants, and their implications for the development of effective control and prophylaxis strategies.


Subject(s)
Betacoronavirus/classification , Betacoronavirus/genetics , Coronavirus Infections/epidemiology , Genetic Heterogeneity , Genome, Viral/genetics , Genome-Wide Association Study/methods , Global Health , Pneumonia, Viral/epidemiology , Amino Acid Sequence/genetics , Antibodies, Neutralizing/immunology , Base Pair Mismatch , Base Sequence/genetics , Climate , Coronavirus Infections/virology , Humans , Open Reading Frames/genetics , Pandemics , Peptidyl-Dipeptidase A/metabolism , Phylogeny , Pneumonia, Viral/virology , Protein Domains/genetics , Protein Domains/immunology , Sequence Deletion , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism
5.
Tidsskr Nor Laegeforen ; 140(11)2020 08 18.
Article in English, Norwegian | MEDLINE | ID: covidwho-724631

ABSTRACT

BACKGROUND: Robust serological assays for SARS-CoV-2 are essential for determining prior infection and the suitability of donated convalescent plasma for plasma therapy. We compared two in-house and three commercial serological assays in a family cohort with SARS-CoV-2-infected members. CASE PRESENTATION: Three individuals in a family of five developed COVID-19 confirmed by PCR, following a trip abroad. Three to four weeks after the onset of symptoms, three commercial ELISAs and an in-house immunofluorescence test demonstrated antibodies to SARS-CoV-2. An in-house neutralisation test also demonstrated neutralising antibodies. INTERPRETATION: The in-house assays and one commercial assay gave congruent results, which were also consistent with the initial PCR and/or clinical evaluation, indicating prior infection in three of the five family members. The other commercial assays indicated possible infection in a fourth family member, but this result was likely due to cross-reactivity. The neutralising antibodies suggest complete or partial immunity against reinfection.


Subject(s)
Antibodies, Viral/immunology , Antibody Formation , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , Antibodies, Neutralizing/immunology , Betacoronavirus , Enzyme-Linked Immunosorbent Assay , Family Health , Fluorescent Antibody Technique , Humans , Neutralization Tests , Pandemics , Serologic Tests
6.
Nat Commun ; 11(1): 4198, 2020 08 21.
Article in English | MEDLINE | ID: covidwho-724360

ABSTRACT

COVID-19 caused by SARS-CoV-2 has become a global pandemic requiring the development of interventions for the prevention or treatment to curtail mortality and morbidity. No vaccine to boost mucosal immunity, or as a therapeutic, has yet been developed to SARS-CoV-2. In this study, we discover and characterize a cross-reactive human IgA monoclonal antibody, MAb362. MAb362 binds to both SARS-CoV and SARS-CoV-2 spike proteins and competitively blocks ACE2 receptor binding, by overlapping the ACE2 structural binding epitope. Furthermore, MAb362 IgA neutralizes both pseudotyped SARS-CoV and SARS-CoV-2 in 293 cells expressing ACE2. When converted to secretory IgA, MAb326 also neutralizes authentic SARS-CoV-2 virus while the IgG isotype shows no neutralization. Our results suggest that SARS-CoV-2 specific IgA antibodies, such as MAb362, may provide effective immunity against SARS-CoV-2 by inducing mucosal immunity within the respiratory system, a potentially critical feature of an effective vaccine.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Immunoglobulin A/immunology , Peptidyl-Dipeptidase A/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Chlorocebus aethiops , Cross Reactions , Epitopes , HEK293 Cells , Humans , Immunoglobulin A/metabolism , Immunoglobulin A, Secretory/immunology , Immunoglobulin A, Secretory/metabolism , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Models, Molecular , Mutation , Protein Binding , Protein Interaction Domains and Motifs , SARS Virus/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
8.
Nat Commun ; 11(1): 4059, 2020 08 13.
Article in English | MEDLINE | ID: covidwho-720832

ABSTRACT

Virus neutralization remains the gold standard for determining antibody efficacy. Therefore, a high-throughput assay to measure SARS-CoV-2 neutralizing antibodies is urgently needed for COVID-19 serodiagnosis, convalescent plasma therapy, and vaccine development. Here, we report on a fluorescence-based SARS-CoV-2 neutralization assay that detects SARS-CoV-2 neutralizing antibodies in COVID-19 patient specimens and yields comparable results to plaque reduction neutralizing assay, the gold standard of serological testing. The fluorescence-based neutralization assay is specific to measure COVID-19 neutralizing antibodies without cross reacting with patient specimens with other viral, bacterial, or parasitic infections. Collectively, our approach offers a rapid platform that can be scaled to screen people for antibody protection from COVID-19, a key parameter necessary to safely reopen local communities.


Subject(s)
Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Pneumonia, Viral/diagnosis , Viral Vaccines/immunology , Animals , Chlorocebus aethiops , Coronavirus Infections/immunology , Coronavirus Infections/prevention & control , Coronavirus Infections/virology , High-Throughput Screening Assays/methods , Humans , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/virology , Serologic Tests/methods , Vero Cells , Viral Plaque Assay
15.
Int J Mol Sci ; 21(14)2020 Jul 21.
Article in English | MEDLINE | ID: covidwho-670344

ABSTRACT

Coronavirus 2 (CoV) Severe Acute Respiratory Syndrome (SARS-CoV2) is causing a highly infectious pandemic pneumonia. Coronaviruses are positive sense single-stranded RNA viruses that infect several animal species, causing symptoms that range from those similar to the common cold to severe respiratory syndrome. The Angiotensin Converting Enzyme 2 (ACE2) is the SARS-CoV2 functional receptor. Measures are currently undertaken worldwide to control the infection to avoid disruption of the social and economic equilibrium, especially in countries with poor healthcare resources. In a guarded optimistic view, we hope that the undertaken preventive and treatment measures will at least contribute to contain viral diffusion, attenuate activity, or even eliminate SARS-CoV2. In this review, we discuss emerging perspectives for prevention/treatment of COVID-19 infection. In addition to vaccines under development, passive immunization is an open opportunity since patients develop neutralizing antibodies. A full spectrum of potential drugs for COVID-19 infections could in turn affect virus binding or enzymatic activities involved in viral replication and transcription. Furthermore, clinical trials are currently evaluating the safety and efficacy of anti-inflammatory drugs, such as tocilizumab. Bioinformatics may allow characterization of specific CD8+ and CD4+ T cell responses; thus, CoV2 T cells' frequency can be correlated with the disease severity and outcome. Combinatorial antibody phage display may be empowered to identify the immune repertoire of CoV2-specific neutralizing antibodies.


Subject(s)
Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/therapeutic use , Antiviral Agents/therapeutic use , Coronavirus Infections , Immunization, Passive/methods , Pandemics , Pneumonia, Viral , A549 Cells , Animals , Anti-Inflammatory Agents/therapeutic use , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/drug effects , Betacoronavirus/immunology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Cell Line , Chlorocebus aethiops , Coronavirus Infections/diagnosis , Coronavirus Infections/drug therapy , Coronavirus Infections/prevention & control , Humans , Lymphocyte Count , Pandemics/prevention & control , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/diagnosis , Pneumonia, Viral/drug therapy , Pneumonia, Viral/prevention & control , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
16.
Science ; 369(6499): 77-81, 2020 07 03.
Article in English | MEDLINE | ID: covidwho-667322

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented public health crisis. Because of the novelty of the virus, there are currently no SARS-CoV-2-specific treatments or vaccines available. Therefore, rapid development of effective vaccines against SARS-CoV-2 are urgently needed. Here, we developed a pilot-scale production of PiCoVacc, a purified inactivated SARS-CoV-2 virus vaccine candidate, which induced SARS-CoV-2-specific neutralizing antibodies in mice, rats, and nonhuman primates. These antibodies neutralized 10 representative SARS-CoV-2 strains, suggesting a possible broader neutralizing ability against other strains. Three immunizations using two different doses, 3 or 6 micrograms per dose, provided partial or complete protection in macaques against SARS-CoV-2 challenge, respectively, without observable antibody-dependent enhancement of infection. These data support the clinical development and testing of PiCoVacc for use in humans.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Betacoronavirus/immunology , Coronavirus Infections/prevention & control , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Viral Vaccines , Animals , Antibodies, Neutralizing/biosynthesis , Antibodies, Neutralizing/immunology , Antibodies, Viral/biosynthesis , Antibodies, Viral/immunology , Betacoronavirus/isolation & purification , Chlorocebus aethiops , Coronavirus Infections/immunology , Coronavirus Infections/virology , Dose-Response Relationship, Immunologic , Female , Immunogenicity, Vaccine , Immunoglobulin G/biosynthesis , Immunoglobulin G/blood , Immunoglobulin G/immunology , Macaca mulatta , Male , Mice , Mice, Inbred BALB C , Pilot Projects , Pneumonia, Viral/virology , Rats , Rats, Wistar , Vaccines, Inactivated/administration & dosage , Vaccines, Inactivated/adverse effects , Vaccines, Inactivated/immunology , Vero Cells , Viral Load , Viral Vaccines/administration & dosage , Viral Vaccines/adverse effects , Viral Vaccines/immunology
17.
EBioMedicine ; 58: 102890, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-666030

ABSTRACT

BACKGROUND: The novel coronavirus (SARS-CoV-2) shares approximately 80% whole genome sequence identity and 66% spike (S) protein identity with that of SARS-CoV. The cross-neutralization between these viruses is currently not well-defined. METHODS: Here, by using the live SARS-CoV-2 virus infection assay as well as HIV-1 based pseudotyped-virus carrying the spike (S) gene of the SARS-CoV-2 (ppSARS-2) and SARS-CoV (ppSARS), we examined whether infections with SARS-CoV and SARS-CoV-2 can induce cross-neutralizing antibodies. FINDINGS: We confirmed that SARS-CoV-2 infects cells via angiotensin converting enzyme 2 (ACE2), the functional receptor for SARS-CoV, and we also found that the recombinant receptor binding domain (RBD) of the S protein of SARS-CoV effectively inhibits ppSARS-2 entry in Huh7.5 cells. However, convalescent sera from SARS-CoV and SARS-CoV-2 patients showed high neutralizing activity only against the homologous virus, with no or limited cross-neutralization activity against the other pseudotyped virus. Similar results were also observed in vaccination studies in mice. INTERPRETATION: Our study demonstrates that although both SARS-CoV and SARS-CoV-2 use ACE2 as a cellular receptor, the neutralization epitopes are not shared by these two closely-related viruses, highlighting challenges towards developing a universal vaccine against SARS-CoV related viruses. FUNDING: This work was supported by the National Key Research and Development Program of China, the National Major Project for Control and Prevention of Infectious Disease in China, and the One Belt and One Road Major Project for infectious diseases.


Subject(s)
Antibodies, Viral/immunology , Betacoronavirus/immunology , Cross Reactions , SARS Virus/immunology , Animals , Antibodies, Neutralizing/immunology , Antibody Specificity , Betacoronavirus/genetics , CHO Cells , Cell Line, Tumor , Cricetinae , Cricetulus , Female , Humans , Mice , Mice, Inbred BALB C , SARS Virus/genetics , Sequence Homology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
18.
Nature ; 584(7821): 450-456, 2020 08.
Article in English | MEDLINE | ID: covidwho-664494

ABSTRACT

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic continues, with devasting consequences for human lives and the global economy1,2. The discovery and development of virus-neutralizing monoclonal antibodies could be one approach to treat or prevent infection by this coronavirus. Here we report the isolation of sixty-one SARS-CoV-2-neutralizing monoclonal antibodies from five patients infected with SARS-CoV-2 and admitted to hospital with severe coronavirus disease 2019 (COVID-19). Among these are nineteen antibodies that potently neutralized authentic SARS-CoV-2 in vitro, nine of which exhibited very high potency, with 50% virus-inhibitory concentrations of 0.7 to 9 ng ml-1. Epitope mapping showed that this collection of nineteen antibodies was about equally divided between those directed against the receptor-binding domain (RBD) and those directed against the N-terminal domain (NTD), indicating that both of these regions at the top of the viral spike are immunogenic. In addition, two other powerful neutralizing antibodies recognized quaternary epitopes that overlap with the domains at the top of the spike. Cryo-electron microscopy reconstructions of one antibody that targets the RBD, a second that targets the NTD, and a third that bridges two separate RBDs showed that the antibodies recognize the closed, 'all RBD-down' conformation of the spike. Several of these monoclonal antibodies are promising candidates for clinical development as potential therapeutic and/or prophylactic agents against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Epitopes, B-Lymphocyte/immunology , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/ultrastructure , Antibodies, Neutralizing/analysis , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/ultrastructure , Antibodies, Viral/analysis , Antibodies, Viral/chemistry , Antibodies, Viral/ultrastructure , Betacoronavirus/chemistry , Betacoronavirus/ultrastructure , Coronavirus Infections/prevention & control , Cryoelectron Microscopy , Disease Models, Animal , Epitope Mapping , Epitopes, B-Lymphocyte/chemistry , Epitopes, B-Lymphocyte/ultrastructure , Female , Humans , Immunoglobulin Fab Fragments/chemistry , Immunoglobulin Fab Fragments/immunology , Immunoglobulin Fab Fragments/ultrastructure , Lung/pathology , Lung/virology , Male , Mesocricetus , Models, Molecular , Neutralization Tests , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Spike Glycoprotein, Coronavirus/ultrastructure
20.
Sci Transl Med ; 12(555)2020 08 05.
Article in English | MEDLINE | ID: covidwho-655207

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic, caused by infection with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is having a deleterious impact on health services and the global economy, highlighting the urgent need for an effective vaccine. Such a vaccine would need to rapidly confer protection after one or two doses and would need to be manufactured using components suitable for scale up. Here, we developed an Alphavirus-derived replicon RNA vaccine candidate, repRNA-CoV2S, encoding the SARS-CoV-2 spike (S) protein. The RNA replicons were formulated with lipid inorganic nanoparticles (LIONs) that were designed to enhance vaccine stability, delivery, and immunogenicity. We show that a single intramuscular injection of the LION/repRNA-CoV2S vaccine in mice elicited robust production of anti-SARS-CoV-2 S protein IgG antibody isotypes indicative of a type 1 T helper cell response. A prime/boost regimen induced potent T cell responses in mice including antigen-specific responses in the lung and spleen. Prime-only immunization of aged (17 months old) mice induced smaller immune responses compared to young mice, but this difference was abrogated by booster immunization. In nonhuman primates, prime-only immunization in one intramuscular injection site or prime/boost immunizations in five intramuscular injection sites elicited modest T cell responses and robust antibody responses. The antibody responses persisted for at least 70 days and neutralized SARS-CoV-2 at titers comparable to those in human serum samples collected from individuals convalescing from COVID-19. These data support further development of LION/repRNA-CoV2S as a vaccine candidate for prophylactic protection against SARS-CoV-2 infection.


Subject(s)
Alphavirus/genetics , Antibodies, Neutralizing/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Pneumonia, Viral/immunology , RNA, Viral/genetics , Replicon/genetics , T-Lymphocytes/immunology , Viral Vaccines/immunology , Animals , Antibody Formation/immunology , Coronavirus Infections/prevention & control , Inorganic Chemicals/chemistry , Lipids/chemistry , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Nanoparticles/chemistry , Pandemics , Primates
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