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1.
Front Immunol ; 13: 864775, 2022.
Article in English | MEDLINE | ID: covidwho-1862607

ABSTRACT

The SARS-CoV-2 pandemic and particularly the emerging variants have deepened the need for widely available therapeutic options. We have demonstrated that hexamer-enhancing mutations in the Fc region of anti-SARS-CoV IgG antibodies lead to a noticeable improvement in IC50 in both pseudo and live virus neutralization assay compared to parental molecules. We also show that hexamer-enhancing mutants improve C1q binding to target surface. To our knowledge, this is the first time this format has been explored for application in viral neutralization and the studies provide proof-of-concept for the use of hexamer-enhanced IgG1 molecules as potential anti-viral therapeutics.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Immunoglobulin G/genetics , Immunologic Tests , Pandemics , SARS-CoV-2/genetics
2.
J Immunol Methods ; 500: 113182, 2022 01.
Article in English | MEDLINE | ID: covidwho-1768318

ABSTRACT

Serology tests for SARS-CoV-2 have proven to be important tools to fight against the COVID-19 pandemic. These serological tests can be used in low-income and remote areas for patient contact tracing, epidemiologic studies and vaccine efficacy evaluations. In this study, we used a semi-stable mammalian episomal expression system to produce high quantities of the receptor-binding domain-RBD of SARS-CoV-2 in a simple and very economical way. The recombinant antigen was tested in an in-house IgG ELISA for COVID-19 with a panel of human sera. A performance comparison of this serology test with a commercial test based on the full-length spike protein showed 100% of concordance between tests. Thus, this serological test can be an attractive and inexpensive option in scenarios of limited resources to face the COVID-19 pandemic.


Subject(s)
COVID-19 Serological Testing/methods , COVID-19/diagnosis , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/metabolism , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/economics , COVID-19 Serological Testing/economics , Costs and Cost Analysis , Enzyme-Linked Immunosorbent Assay , Genetic Engineering , Humans , Immunoglobulin G/genetics , Immunoglobulin G/metabolism , Protein Binding , Protein Interaction Domains and Motifs/genetics , Spike Glycoprotein, Coronavirus/genetics
3.
J Virol ; 96(4): e0160021, 2022 02 23.
Article in English | MEDLINE | ID: covidwho-1759291

ABSTRACT

A comprehensive study of the B cell response against SARS-CoV-2 could be significant for understanding the immune response and developing therapeutical antibodies and vaccines. To define the dynamics and characteristics of the antibody repertoire following SARS-CoV-2 infection, we analyzed the mRNA transcripts of immunoglobulin heavy chain (IgH) repertoires of 24 peripheral blood samples collected between 3 and 111 days after symptom onset from 10 COVID-19 patients. Massive clonal expansion of naive B cells with limited somatic hypermutation (SHM) was observed in the second week after symptom onset. The proportion of low-SHM IgG clones strongly correlated with spike-specific IgG antibody titers, highlighting the significant activation of naive B cells in response to a novel virus infection. The antibody isotype switching landscape showed a transient IgA surge in the first week after symptom onset, followed by a sustained IgG elevation that lasted for at least 3 months. SARS-CoV-2 infection elicited poly-germ line reactive antibody responses. Interestingly, 17 different IGHV germ line genes recombined with IGHJ6 showed significant clonal expansion. By comparing the IgH repertoires that we sequenced with the 774 reported SARS-CoV-2-reactive monoclonal antibodies (MAbs), 13 shared spike-specific IgH clusters were found. These shared spike-specific IgH clusters are derived from the same lineage of several recently published neutralizing MAbs, including CC12.1, CC12.3, C102, REGN10977, and 4A8. Furthermore, identical spike-specific IgH sequences were found in different COVID-19 patients, suggesting a highly convergent antibody response to SARS-CoV-2. Our analysis based on sequencing antibody repertoires from different individuals revealed key signatures of the systemic B cell response induced by SARS-CoV-2 infection. IMPORTANCE Although the canonical delineation of serum antibody responses following SARS-CoV-2 infection has been well established, the dynamics of antibody repertoire at the mRNA transcriptional level has not been well understood, especially the correlation between serum antibody titers and the antibody mRNA transcripts. In this study, we analyzed the IgH transcripts and characterized the B cell clonal expansion and differentiation, isotype switching, and somatic hypermutation in COVID-19 patients. This study provided insights at the repertoire level for the B cell response after SARS-CoV-2 infection.


Subject(s)
Antibodies, Neutralizing/genetics , Antibodies, Viral/genetics , B-Lymphocytes/immunology , COVID-19/genetics , Immunoglobulin G/genetics , Receptors, Antigen, B-Cell/genetics , SARS-CoV-2/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Humans , Immunoglobulin G/immunology , Receptors, Antigen, B-Cell/immunology
4.
Commun Biol ; 4(1): 1389, 2021 12 16.
Article in English | MEDLINE | ID: covidwho-1585764

ABSTRACT

In light of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants potentially undermining humoral immunity, it is important to understand the fine specificity of the antiviral antibodies. We screened 20 COVID-19 patients for antibodies against 9 different SARS-CoV-2 proteins observing responses against the spike (S) proteins, the receptor-binding domain (RBD), and the nucleocapsid (N) protein which were of the IgG1 and IgG3 subtypes. Importantly, mutations which typically occur in the B.1.351 "South African" variant, significantly reduced the binding of anti-RBD antibodies. Nine of 20 patients were critically ill and were considered high-risk (HR). These patients showed significantly higher levels of transforming growth factor beta (TGF-ß) and myeloid-derived suppressor cells (MDSC), and lower levels of CD4+ T cells expressing LAG-3 compared to standard-risk (SR) patients. HR patients evidenced significantly higher anti-S1/RBD IgG antibody levels and an increased neutralizing activity. Importantly, a large proportion of S protein-specific antibodies were glycosylation-dependent and we identified a number of immunodominant linear epitopes within the S1 and N proteins. Findings derived from this study will not only help us to identify the most relevant component of the anti-SARS-CoV-2 humoral immune response but will also enable us to design more meaningful immunomonitoring methods for anti-COVID-19 vaccines.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , SARS-CoV-2/immunology , Viral Proteins/immunology , Adaptive Immunity/immunology , Adult , Aged , COVID-19/virology , COVID-19 Vaccines/immunology , Coronavirus Nucleocapsid Proteins/genetics , Coronavirus Nucleocapsid Proteins/immunology , Coronavirus Nucleocapsid Proteins/metabolism , Female , Humans , Immunity, Humoral/immunology , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Male , Middle Aged , Mutation , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Viral Proteins/genetics , Viral Proteins/metabolism
5.
MAbs ; 14(1): 2002236, 2022.
Article in English | MEDLINE | ID: covidwho-1585298

ABSTRACT

Coronavirus disease 2019 (COVID-19) is an evolving global public health crisis in need of therapeutic options. Passive immunization of monoclonal antibodies (mAbs) represents a promising therapeutic strategy capable of conferring immediate protection from SARS-CoV-2 infection. Herein, we describe the discovery and characterization of neutralizing SARS-CoV-2 IgG and VHH antibodies from four large-scale phage libraries. Each library was constructed synthetically with shuffled complementarity-determining region loops from natural llama and human antibody repertoires. While most candidates targeted the receptor-binding domain of the S1 subunit of SARS-CoV-2 spike protein, we also identified a neutralizing IgG candidate that binds a unique epitope on the N-terminal domain. A select number of antibodies retained binding to SARS-CoV-2 variants Alpha, Beta, Gamma, Kappa and Delta. Overall, our data show that synthetic phage libraries can rapidly yield SARS-CoV-2 S1 antibodies with therapeutically desirable features, including high affinity, unique binding sites, and potent neutralizing activity in vitro, and a capacity to limit disease in vivo.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Cell Surface Display Techniques , Immunoglobulin G/immunology , Peptide Library , SARS-CoV-2/immunology , Single-Domain Antibodies/immunology , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/metabolism , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/genetics , Antibodies, Viral/metabolism , Antibody Specificity , Binding Sites, Antibody , COVID-19/metabolism , COVID-19/prevention & control , COVID-19/virology , Chlorocebus aethiops , Disease Models, Animal , Epitopes , Female , Host-Pathogen Interactions , Immunoglobulin G/genetics , Immunoglobulin G/metabolism , Immunoglobulin G/pharmacology , Mesocricetus , SARS-CoV-2/pathogenicity , Single-Domain Antibodies/genetics , Single-Domain Antibodies/metabolism , Single-Domain Antibodies/pharmacology , Vero Cells
6.
Mol Biotechnol ; 63(12): 1223-1234, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1321871

ABSTRACT

COVID-19, caused by SARS-CoV-2, is currently spreading around the world and causing many casualties. Antibodies against such emerging infectious diseases are one of the important tools for basic viral research and the development of diagnostic and therapeutic agents. CR3022 is a monoclonal antibody against the receptor binding domain (RBD) of the spike protein (S protein) of SARS-CoV found in SARS patients, but it was also shown to have strong affinity for that of SARS-CoV-2. In this study, we produced large amounts of three formats of CR3022 antibodies (scFv, Fab and IgG) with high purity using a silkworm-baculovirus expression vector system. Furthermore, SPR measurements showed that the affinity of those silkworm-produced IgG antibodies to S protein was almost the same as that produced in mammalian expression system. These results indicate that the silkworm-baculovirus expression system is an excellent expression system for emerging infectious diseases that require urgent demand for diagnostic agents and therapeutic agents.


Subject(s)
Antibodies, Monoclonal/biosynthesis , Antibodies, Neutralizing/biosynthesis , Antibodies, Viral/biosynthesis , COVID-19/immunology , COVID-19/virology , SARS-CoV-2/immunology , Animals , Antibodies, Monoclonal/genetics , Antibodies, Neutralizing/genetics , Antibodies, Viral/genetics , Antibody Affinity , Baculoviridae/genetics , Baculoviridae/immunology , Biotechnology , Bombyx/genetics , Bombyx/immunology , Cells, Cultured , Gene Expression , Hemolymph/immunology , Humans , Immunoglobulin Fab Fragments/biosynthesis , Immunoglobulin Fab Fragments/genetics , Immunoglobulin Fragments/biosynthesis , Immunoglobulin G/biosynthesis , Immunoglobulin G/genetics , SARS-CoV-2/genetics , Single-Chain Antibodies/biosynthesis , Single-Chain Antibodies/genetics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
7.
Nature ; 596(7872): 417-422, 2021 08.
Article in English | MEDLINE | ID: covidwho-1287811

ABSTRACT

Although two-dose mRNA vaccination provides excellent protection against SARS-CoV-2, there is little information about vaccine efficacy against variants of concern (VOC) in individuals above eighty years of age1. Here we analysed immune responses following vaccination with the BNT162b2 mRNA vaccine2 in elderly participants and younger healthcare workers. Serum neutralization and levels of binding IgG or IgA after the first vaccine dose were lower in older individuals, with a marked drop in participants over eighty years old. Sera from participants above eighty showed lower neutralization potency against the B.1.1.7 (Alpha), B.1.351 (Beta) and P.1. (Gamma) VOC than against the wild-type virus and were more likely to lack any neutralization against VOC following the first dose. However, following the second dose, neutralization against VOC was detectable regardless of age. The frequency of SARS-CoV-2 spike-specific memory B cells was higher in elderly responders (whose serum showed neutralization activity) than in non-responders after the first dose. Elderly participants showed a clear reduction in somatic hypermutation of class-switched cells. The production of interferon-γ and interleukin-2 by SARS-CoV-2 spike-specific T cells was lower in older participants, and both cytokines were secreted primarily by CD4 T cells. We conclude that the elderly are a high-risk population and that specific measures to boost vaccine responses in this population are warranted, particularly where variants of concern are circulating.


Subject(s)
Aging/immunology , COVID-19 Vaccines/immunology , Immunity , SARS-CoV-2/immunology , Adult , Aged , Aged, 80 and over , Aging/blood , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , Autoantibodies/immunology , B-Lymphocytes/cytology , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , COVID-19 Vaccines/administration & dosage , Female , Health Personnel , Humans , Immunity/genetics , Immunization, Secondary , Immunoglobulin A/immunology , Immunoglobulin Class Switching , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Immunologic Memory/immunology , Inflammation/blood , Inflammation/immunology , Interferon-gamma/immunology , Interleukin-2/immunology , Male , Middle Aged , Somatic Hypermutation, Immunoglobulin , Spike Glycoprotein, Coronavirus/immunology , T-Lymphocytes/immunology , Vaccination , Vaccines, Synthetic/administration & dosage , Vaccines, Synthetic/immunology
8.
J Immunol Methods ; 495: 113082, 2021 08.
Article in English | MEDLINE | ID: covidwho-1243047

ABSTRACT

The development of new diagnostic assays become a priority for managing COVID-19. To this aim, we presented here an in-house ELISA based on the production of two major recombinant and high-quality antigens from SARS-CoV-2. Full-length N and S-RBD fragment proteins fused to mouse IgG2a-Fc were produced in the CHO cell line. Secreted recombinant proteins were easily purified with standard Protein A chromatography and were used in an in-house ELISA to detect anti-N and anti-RBD IgGs in the plasma of COVID-19 RTPCR-positive patients. High reactivity against recombinant antigens was readily detected in all positive plasma samples, whereas no recognition was observed with control healthy subject's plasmas. Remarkably, unpurified recombinant N protein obtained from cell culture supernatant was also suitable for the monitoring by ELISA of IgG levels in positive patients. This work provides an early prospection for low price but high-quality serological kit development.


Subject(s)
COVID-19 Serological Testing/methods , COVID-19/immunology , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin Fc Fragments/metabolism , Immunoglobulin G/metabolism , Recombinant Proteins/metabolism , SARS-CoV-2/physiology , Animals , Antibodies, Viral/blood , CHO Cells , COVID-19 Serological Testing/economics , Costs and Cost Analysis , Cricetulus , Humans , Immunoglobulin Fc Fragments/genetics , Immunoglobulin G/genetics , Recombinant Proteins/genetics , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology
9.
Brief Bioinform ; 22(6)2021 11 05.
Article in English | MEDLINE | ID: covidwho-1236217

ABSTRACT

The world is facing a pandemic of Corona Virus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Adaptive immune responses are essential for SARS-CoV-2 virus clearance. Although a large body of studies have been conducted to investigate the immune mechanism in COVID-19 patients, we still lack a comprehensive understanding of the BCR repertoire in patients. In this study, we used the single-cell V(D)J sequencing to characterize the BCR repertoire across convalescent COVID-19 patients. We observed that the BCR diversity was significantly reduced in disease compared with healthy controls. And BCRs tend to skew toward different V gene segments in COVID-19 and healthy controls. The CDR3 sequences of heavy chain in clonal BCRs in patients were more convergent than that in healthy controls. In addition, we discovered increased IgG and IgA isotypes in the disease, including IgG1, IgG3 and IgA1. In all clonal BCRs, IgG isotypes had the most frequent class switch recombination events and the highest somatic hypermutation rate, especially IgG3. Moreover, we found that an IgG3 cluster from different clonal groups had the same IGHV, IGHJ and CDR3 sequences (IGHV4-4-CARLANTNQFYDSSSYLNAMDVW-IGHJ6). Overall, our study provides a comprehensive characterization of the BCR repertoire in COVID-19 patients, which contributes to the understanding of the mechanism for the immune response to SARS-CoV-2 infection.


Subject(s)
COVID-19/immunology , Receptors, Antigen, B-Cell/genetics , SARS-CoV-2/immunology , VDJ Exons/genetics , B-Lymphocytes/immunology , COVID-19/genetics , COVID-19/virology , Female , Humans , Immunoglobulin A/genetics , Immunoglobulin A/immunology , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Male , Receptors, Antigen, B-Cell/immunology , SARS-CoV-2/pathogenicity , Sequence Analysis , Single-Cell Analysis , VDJ Exons/immunology
10.
Nat Commun ; 12(1): 1577, 2021 03 11.
Article in English | MEDLINE | ID: covidwho-1132068

ABSTRACT

COVID-19 is a severe acute respiratory disease caused by SARS-CoV-2, a new recently emerged sarbecovirus. This virus uses the human ACE2 enzyme as receptor for cell entry, recognizing it with the receptor binding domain (RBD) of the S1 subunit of the viral spike protein. We present the use of phage display to select anti-SARS-CoV-2 spike antibodies from the human naïve antibody gene libraries HAL9/10 and subsequent identification of 309 unique fully human antibodies against S1. 17 antibodies are binding to the RBD, showing inhibition of spike binding to cells expressing ACE2 as scFv-Fc and neutralize active SARS-CoV-2 virus infection of VeroE6 cells. The antibody STE73-2E9 is showing neutralization of active SARS-CoV-2 as IgG and is binding to the ACE2-RBD interface. Thus, universal libraries from healthy human donors offer the advantage that antibodies can be generated quickly and independent from the availability of material from recovering patients in a pandemic situation.


Subject(s)
Angiotensin-Converting Enzyme 2/immunology , Antibodies, Neutralizing/genetics , Antibodies, Viral/genetics , COVID-19/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Angiotensin-Converting Enzyme 2/chemistry , Animals , Antibodies, Neutralizing/isolation & purification , Antibodies, Viral/isolation & purification , Antibody Affinity , COVID-19/epidemiology , Cell Line , Chlorocebus aethiops , Gene Library , Healthy Volunteers , Host Microbial Interactions/immunology , Humans , Immunoglobulin G/genetics , Immunoglobulin G/isolation & purification , Models, Molecular , Mutation , Neutralization Tests , Pandemics , Peptide Library , Protein Interaction Domains and Motifs , Recombinant Proteins/genetics , Recombinant Proteins/immunology , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/chemistry , Vero Cells
11.
PLoS Pathog ; 17(2): e1009165, 2021 02.
Article in English | MEDLINE | ID: covidwho-1079380

ABSTRACT

The interactions between antibodies, SARS-CoV-2 and immune cells contribute to the pathogenesis of COVID-19 and protective immunity. To understand the differences between antibody responses in mild versus severe cases of COVID-19, we analyzed the B cell responses in patients 1.5 months post SARS-CoV-2 infection. Severe, and not mild, infection correlated with high titers of IgG against Spike receptor binding domain (RBD) that were capable of ACE2:RBD inhibition. B cell receptor (BCR) sequencing revealed that VH3-53 was enriched during severe infection. Of the 22 antibodies cloned from two severe donors, six exhibited potent neutralization against authentic SARS-CoV-2, and inhibited syncytia formation. Using peptide libraries, competition ELISA and mutagenesis of RBD, we mapped the epitopes of the neutralizing antibodies (nAbs) to three different sites on the Spike. Finally, we used combinations of nAbs targeting different immune-sites to efficiently block SARS-CoV-2 infection. Analysis of 49 healthy BCR repertoires revealed that the nAbs germline VHJH precursors comprise up to 2.7% of all VHJHs. We demonstrate that severe COVID-19 is associated with unique BCR signatures and multi-clonal neutralizing responses that are relatively frequent in the population. Moreover, our data support the use of combination antibody therapy to prevent and treat COVID-19.


Subject(s)
Antibodies, Monoclonal , Antibodies, Neutralizing , Antibodies, Viral , COVID-19 , Convalescence , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Adult , Aged , Animals , Antibodies, Monoclonal/genetics , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/immunology , Antibodies, Viral/genetics , Antibodies, Viral/immunology , COVID-19/genetics , COVID-19/immunology , Chlorocebus aethiops , Cloning, Molecular , Epitope Mapping , Epitopes/genetics , Epitopes/immunology , Female , Humans , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Male , Middle Aged , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
12.
Nat Commun ; 12(1): 944, 2021 02 11.
Article in English | MEDLINE | ID: covidwho-1078588

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), exhibits high levels of mortality and morbidity and has dramatic consequences on human life, sociality and global economy. Neutralizing antibodies constitute a highly promising approach for treating and preventing infection by this novel pathogen. In the present study, we characterize and further evaluate the recently identified human monoclonal MD65 antibody for its ability to provide protection against a lethal SARS-CoV-2 infection of K18-hACE2 transgenic mice. Eighty percent of the untreated mice succumbed 6-9 days post-infection, while administration of the MD65 antibody as late as 3 days after exposure rescued all infected animals. In addition, the efficiency of the treatment is supported by prevention of morbidity and ablation of the load of infective virions in the lungs of treated animals. The data demonstrate the therapeutic value of human monoclonal antibodies as a life-saving treatment for severe COVID-19 infection.


Subject(s)
Antibodies, Monoclonal/administration & dosage , Antibodies, Neutralizing/administration & dosage , Antibodies, Viral/administration & dosage , COVID-19/immunology , Animals , Antibodies, Monoclonal/genetics , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/immunology , Antibodies, Viral/genetics , Antibodies, Viral/immunology , COVID-19/drug therapy , Chlorocebus aethiops , Female , Immunoglobulin G/administration & dosage , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Lung/pathology , Lung/virology , Male , Mice, Inbred C57BL , Mice, Transgenic , SARS-CoV-2/classification , SARS-CoV-2/physiology , Seroconversion , Vero Cells , Viral Load
13.
JCI Insight ; 6(1)2021 01 11.
Article in English | MEDLINE | ID: covidwho-1066996

ABSTRACT

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), coupled with a lack of therapeutics, has paralyzed the globe. Although significant effort has been invested in identifying antibodies that block infection, the ability of antibodies to target infected cells through Fc interactions may be vital to eliminate the virus. To explore the role of Fc activity in SARS-CoV-2 immunity, the functional potential of a cross-SARS-reactive antibody, CR3022, was assessed. CR3022 was able to broadly drive antibody effector functions, providing critical immune clearance at entry and upon egress. Using selectively engineered Fc variants, no protection was observed after administration of WT IgG1 in mice or hamsters. Conversely, the functionally enhanced Fc variant resulted in increased pathology in both the mouse and hamster models, causing weight loss in mice and enhanced viral replication and weight loss in the more susceptible hamster model, highlighting the pathological functions of Fc-enhancing mutations. These data point to the critical need for strategic Fc engineering for the treatment of SARS-CoV-2 infection.


Subject(s)
Antibodies, Neutralizing/pharmacology , COVID-19/immunology , Immunity, Innate/drug effects , Immunoglobulin Fc Fragments/genetics , Immunoglobulin G/pharmacology , SARS-CoV-2/drug effects , Virus Replication/drug effects , Animals , Antibodies, Monoclonal , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/therapeutic use , COVID-19/drug therapy , COVID-19/physiopathology , Cricetinae , Cross Reactions , Epitopes , Humans , Immunity, Innate/immunology , Immunoglobulin G/genetics , Immunoglobulin G/therapeutic use , Mesocricetus , Mice , Middle East Respiratory Syndrome Coronavirus/drug effects , Middle East Respiratory Syndrome Coronavirus/immunology , Protein Engineering , Receptors, Fc/immunology , SARS Virus/drug effects , SARS Virus/immunology , SARS-CoV-2/immunology , Severity of Illness Index , Spike Glycoprotein, Coronavirus/immunology , THP-1 Cells , Viral Load/drug effects , Weight Loss/drug effects
14.
Nat Commun ; 12(1): 469, 2021 01 20.
Article in English | MEDLINE | ID: covidwho-1039642

ABSTRACT

Antibody cocktails represent a promising approach to prevent SARS-CoV-2 escape. The determinants for selecting antibody combinations and the mechanism that antibody cocktails prevent viral escape remain unclear. We compared the critical residues in the receptor-binding domain (RBD) used by multiple neutralizing antibodies and cocktails and identified a combination of two antibodies CoV2-06 and CoV2-14 for preventing viral escape. The two antibodies simultaneously bind to non-overlapping epitopes and independently compete for receptor binding. SARS-CoV-2 rapidly escapes from individual antibodies by generating resistant mutations in vitro, but it doesn't escape from the cocktail due to stronger mutational constraints on RBD-ACE2 interaction and RBD protein folding requirements. We also identified a conserved neutralizing epitope shared between SARS-CoV-2 and SARS-CoV for antibody CoV2-12. Treatments with CoV2-06 and CoV2-14 individually and in combination confer protection in mice. These findings provide insights for rational selection and mechanistic understanding of antibody cocktails as candidates for treating COVID-19.


Subject(s)
Antibodies, Monoclonal/pharmacology , COVID-19/drug therapy , SARS-CoV-2/drug effects , Angiotensin-Converting Enzyme 2/metabolism , Animals , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/genetics , Antibodies, Viral/immunology , COVID-19/virology , Chlorocebus aethiops , Disease Models, Animal , Female , Humans , Immunoglobulin Fragments/genetics , Immunoglobulin Fragments/immunology , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Mice , Mice, Inbred BALB C , Models, Molecular , Mutation , Protein Binding , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
15.
Clin Chim Acta ; 511: 291-297, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-1023490

ABSTRACT

BACKGROUND: Repositivity of SARS-CoV-2 nucleic acid in discharged COVID-19 patients was reported recently. However, the characteristics of repositive results are still not well understood, leading to a lack of effective monitoring strategies. METHODS: In the present study, a total of 59 COVID-19 patients were enrolled, and the characteristics of the repositive samples were analyzed. RESULTS: The repositive rate in this cohort was 15.79%. The N gene was the main target gene that was positive in the repositive results as well as in the last positive results of all patients. The median duration from diagnosis to the last positive test was 20 days (IQR, 16-31 days), and the longest duration was 40 days. Repositivity was only observed in IgM single- or both IgM- and IgG-positive patients, instead of IgG single-positive patients. CONCLUSIONS: There was a significant proportion of repositives in the recovered COVID-19 patients, and increasing the required number of negatives for consecutive nucleic acid tests may reduce the incidence of repositives. The recommended monitoring strategy for repositivity is monitoring the N gene in IgM-positive patients. This can ensure high sensitivity while reducing the time and cost of nucleic acid detection.


Subject(s)
COVID-19/genetics , Real-Time Polymerase Chain Reaction/methods , SARS-CoV-2/genetics , Aged , COVID-19/diagnosis , COVID-19/epidemiology , China/epidemiology , Cohort Studies , Female , Humans , Immunoglobulin G/genetics , Immunoglobulin M/genetics , Male , Middle Aged , Real-Time Polymerase Chain Reaction/standards , Retrospective Studies
16.
Cell Host Microbe ; 28(4): 516-525.e5, 2020 10 07.
Article in English | MEDLINE | ID: covidwho-743914

ABSTRACT

B cells are critical for the production of antibodies and protective immunity to viruses. Here we show that patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who develop coronavirus disease 2019 (COVID-19) display early recruitment of B cells expressing a limited subset of IGHV genes, progressing to a highly polyclonal response of B cells with broader IGHV gene usage and extensive class switching to IgG and IgA subclasses with limited somatic hypermutation in the initial weeks of infection. We identify convergence of antibody sequences across SARS-CoV-2-infected patients, highlighting stereotyped naive responses to this virus. Notably, sequence-based detection in COVID-19 patients of convergent B cell clonotypes previously reported in SARS-CoV infection predicts the presence of SARS-CoV/SARS-CoV-2 cross-reactive antibody titers specific for the receptor-binding domain. These findings offer molecular insights into shared features of human B cell responses to SARS-CoV-2 and SARS-CoV.


Subject(s)
Antibodies, Viral/immunology , B-Lymphocytes/immunology , Betacoronavirus/immunology , Coronavirus Infections/immunology , Coronavirus Infections/virology , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , Adult , Aged , Aged, 80 and over , Antibodies, Viral/blood , Antibodies, Viral/genetics , Antibody Formation , Betacoronavirus/genetics , COVID-19 , Female , HEK293 Cells , Humans , Immunogenetics , Immunoglobulin A/genetics , Immunoglobulin A/immunology , Immunoglobulin G/genetics , Immunoglobulin G/immunology , Male , Middle Aged , Pandemics , SARS-CoV-2 , Sequence Analysis , Spike Glycoprotein, Coronavirus/immunology
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