B cell epitope mapping of SARS-CoV-2 spike vaccinated rabbits
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ABSTRACT: This experiment aims to profile polyclonal antibody binding profiles in serum from vaccinated animals relative to antibody function in a virus neutralization assay. Rabbits received three vaccinations with a DNA vaccine encoding the spike protein of the SARS-CoV-2 index strain. Serum samples were selected based on a three-tier (low, intermediate, and high) capacity to cross-neutralize SARS-CoV-2 strains with known neutralization resistance. Following normalization of total anti-spike IgG levels, serum of each animal (n=3) were evaluated for antibody binding to 10mer cyclic constrained peptides spanning the entire spike protein and regions with known SARS-CoV-2 variant of concern spike mutations.
Project description:Recent exposure to seasonal coronaviruses (sCoVs) may stimulate cross-reactive antibody responses against SARS-CoV-2. Previous studies have shown divergent results regarding protective or damaging immunity induced by prior exposure to sCoVs. It is still unknown whether pre-existing humoral immunity may play a role in the vaccine-induced neutralization and antibody responses. In this study, we collected 36 paired sera in healthy volunteers before and after immunization with inactivated SARS-CoV-2 vaccines, and analyzed the distribution and intensity of pre-existing antibody responses at the epitope level before vaccine immunization, as well as the relationship between pre-existing sCoVs immunity and vaccine-induced neutralization.
Project description:Recent exposure to seasonal coronaviruses (sCoVs) may stimulate cross-reactive antibody responses against SARS-CoV-2. Previous studies have shown divergent results regarding protective or damaging immunity induced by prior exposure to sCoVs. It is still unknown whether pre-existing humoral immunity may play a role in the vaccine-induced neutralization and antibody responses. In this study, we collected 36 paired sera in healthy volunteers before and after immunization with inactivated SARS-CoV-2 vaccines, and analyzed the distribution and intensity of pre-existing antibody responses at the epitope level before vaccine immunization, as well as the relationship between pre-existing sCoVs immunity and vaccine-induced neutralization.
Project description:The on-going COVID-19 pandemic requires a deeper understanding of the long-term antibody responses that persist following SARS-CoV-2 infection. To that end, we determined epitope-specific IgG antibody responses in COVID-19 convalescent sera collected at 5 months post-diagnosis and compared that to sera from naïve individuals. Each serum sample was reacted with a high-density peptide microarray representing the complete proteome of SARS-CoV-2 as 15 mer peptides with 11 amino acid overlap and homologs of spike glycoprotein, nucleoprotein, membrane protein, and envelope small membrane protein from related human coronaviruses. Binding signatures were compared between COVID-19 convalescent patients and naïve individuals using the web service tool EPIphany.
Project description:The COVID-19 pandemic prompted an unprecedented effort to develop effective countermeasures against SARS-CoV-2. While efficacious vaccines and certain therapeutic monoclonal antibodies are available, here, we report the development, cryo-EM structures and functional analyses of distinct potent monoclonal antibodies (mAbs) that neutralize SARS-CoV-2 and its variant B.1.351. We established a platform for rapid identification of highly potent and specific SARS-CoV-2-neutralizing antibodies by high-throughput B cell receptor single cell sequencing of spike receptor binding domain immunized animals. We identified two highly potent and specific SARS-CoV-2 neutralizing mAb clones that have single-digit nanomolar affinity and low-picomolar avidity. We also generated a bispecific antibody of these two lead clones. The lead monospecific and bispecific antibodies showed strong neutralization ability against prototypical SARS-CoV-2 and the highly contagious South African variant B.1.351 that post a further risk of reducing the efficacy of currently available therapeutic antibodies and vaccines. The lead mAbs showed potent in vivo efficacy against authentic SARS-CoV-2 in both prophylactic and therapeutic settings. We solved five cryo-EM structures at ~3 resolution of these neutralizing antibodies in complex with the ectodomain of the prefusion spike trimer, and revealed the molecular epitopes, binding patterns and conformations between the antibodies and spike RBD, which are distinct from existing antibodies. Our recently developed antibodies expand the repertoire of the toolbox of COVID-19 countermeasures against the SARS-CoV-2 pathogen and its emerging variants.
Project description:Despite the clinical success of anti-spike vaccines, the effectiveness of neutralizing antibodies and vaccines by rapidly spreading SARS-CoV-2 variants has been compromised. Viruses can hijack the glycosylation machinery of host cells to shield themselves from the host’s immune response and attenuate antibody efficiency. However, it still remains unclear whether targeting glycosylation on spike can impair SARS-CoV-2 and its variants infectivity. Methods: To assess the binding ability of glycosylated or deglycosylated spike with ACE2, we performed flow cytometry, ELISA, and BioLayer Interferometry methods. Viral entry ability was determined by luciferase intensity, immunoblotting, and immunofluorescence assay. A genome-wide association study (GWAS) was performed to identify the relationship of STT3A and COVID-19 severity. N-glycosylation regulated by NF-kB/STT3A axis was investigated by knockdown approach, chromatin immunoprecipitation, and promoter assay. To specifically target SARS-CoV-2 infected cells, we developed an antibody-drug conjugate coupling non-neutralization anti-spike antibody with NGI-1 (4G10-ADC) on inhibitory effects of SARS-CoV-2 infection. Results: We found receptor binding domain and three SARS-CoV-2 distinct surface Nglycosylation sites in 57,311 spikes retrieved from NCBI-Virus-database are highly evolutionarily conserved (99.67%) and involved in ACE2 interaction. We further identified STT3A as a key glycosyltransferase that catalyzed spike glycosylation and positively correlated with COVID-19 severity. Inhibition of STT3A by N-linked glycosylation inhibitor-1 (NGI-1) impaired SARS-CoV-2 and its variants (B.1.1.7, and B.1.351) infectivity. Most importantly, 4G10-ADC internalized SARS-CoV-2 infected cells and subsequently released NGI-1 to deglycosylate spike protein. Thereby, it reinforces the neutralizing abilities in antibodies, vaccines, or convalescent sera, inhibiting SARS-CoV-2 and its variants’ infectivity. Our results suggest targeting STT3A-mediated evolution conserved glycosylation via ADC can provide a widespread impact on SARS-CoV-2 variants infection. Together, we identified a novel deglycosylation method to eradicate SARS-CoV-2 variants infection.
Project description:The experiment aims at characterizing the immune responses elicited by the BNT162b2 vaccine against SARS-CoV-2, initially administered in a two dose regimen (second dose after three weeks followinf the first dose) In particular the transcriptional landscape of circulating T and B lymphocytes has been profiled longitudinnaly by scRNA-seq coupleD with CITE-seq of 19 cell surface markers to better classify T cells subpopulations, LIBRA-seq to assess the Spike-specificity of BCRs and and V(D)J seq to also track T and B cell clones dynamics. Eeach sample was profiled before vaccination (T0), 21 days after the first dose (T1), 2 months after the first dose (1 month after the second dose) (T2). The immune responses were characterized using PBMC from 3 SARS-CoV-2 experienced donors (experiencing SARS-Cov-2 at least 4 months before the first vaccinatin) and 2 SARS-CoV-2 unexperienced donors.
Project description:We generated LNP-mRNA encoding B.1.1.529 SARS-CoV-2 spike, and intramuscularly administered it in a human IgG and IgK knock-in mouse. Single cell VDJ-seq unveiled the sequences of human monoclonal antibodies targeting the B.1.1.529 SARS-CoV-2 spike protein.
Project description:Intranasal vaccines can prime or recruit to the respiratory epithelium mucosal immune cells capable of preventing transmission of SARS-CoV-2. We found that a single intranasal dose of serotype 5-based adenoviral vectors expressing either the receptor binding domain (Ad5-RBD) or the complete ectodomain (Ad5-S) of the SARS-CoV-2 spike protein was effective in inducing i) secretory and serum anti-spike IgA and IgG, ii) robust SARS-CoV-2-neutralizing activity in the serum and in respiratory secretions, iii) rigorous spike-directed T helper 1 cell/cytotoxic T cell immunity, and iv) protection of wild-type mice from a challenge with the SARS-CoV-2 beta variant. Our data confirm and extend previous studies reporting promising preclinical results on vector-based intranasal SARS-CoV-2 vaccination, and support the potential of this approach to elicit mucosal immunity for preventing reinfection and transmission of SARS-CoV-2 more effectively than the currently available vaccines.
Project description:We investigated the kinetics, breadth, magnitude, and level of cross-reactivity of IgG antibodies against SARS-CoV-2 and heterologous seasonal (HCoV-NL63, -229E, -OC43 and -HKU1) and epidemic coronaviruses (SARS-CoV, hCoV-MERS) at the clonal level in patients with mild or severe COVID-19 as well as in disease control patients. We assessed IgG antibody reactivity to nucleocapsid and spike antigens using protein microarray. A cutoff was set at the average plus 3 times the SD of 20 nonreactive cultures with a minimum MFI of 1000.