Project description:Global containment of COVID-19 still requires accessible and affordable vaccines for low- and middle-income countries (LMICs). Recently approved vaccines provide needed interventions, albeit at prices that may limit their global access. Subunit vaccines based on recombinant proteins are suited for large-volume microbial manufacturing to yield billions of doses annually, minimizing their manufacturing cost. These types of vaccines are well-established, proven interventions with multiple safe and efficacious commercial examples. Many vaccine candidates of this type for SARS-CoV-2 rely on sequences containing the receptor-binding domain (RBD), which mediates viral entry to cells via ACE2. Here we report an engineered sequence variant of RBD that exhibits high-yield manufacturability, high-affinity binding to ACE2, and enhanced immunogenicity after a single dose in mice compared to the Wuhan-Hu-1 variant used in current vaccines. Antibodies raised against the engineered protein exhibited heterotypic binding to the RBD from two recently reported SARS-CoV-2 variants of concern (501Y.V1/V2). Presentation of the engineered RBD on a designed virus-like particle (VLP) also reduced weight loss in hamsters upon viral challenge.
Project description:The COVID-19 pandemic is an infectious disease caused by SARS-CoV-2. The first step of SARS-CoV-2 infection is the recognition of angiotensin-converting enzyme 2 (hACE2) receptors by the receptor-binding domain (RBD) of the viral spike (S) glycoprotein. Although the molecular and structural bases of the SARS-CoV-2-RBD/hACE2 interaction have been thoroughly investigated in vitro, the relationship between hACE2 expression and in vivo infection is less understood. Here, we developed an efficient SARS-CoV-2-RBD binding assay suitable for super resolution microscopy and simultaneous hACE2 immunodetection and mapped the correlation between hACE2 receptor abundance and SARS-CoV-2-RBD binding, both in vitro and in human lung biopsies. Next, we explored the specific proteome of SARS-CoV-2-RBD/hACE2 through a comparative mass spectrometry approach. We found that only a minority of hACE2 positive spots are actually SARS-CoV-2-RBD binding sites, and that the relationship between SARS-CoV-2-RBD binding and hACE2 presence is variable, suggesting the existence of additional factors. Indeed, we found several interactors that are involved in receptor localization and viral entry and characterized one of them: SLC1A5, an amino acid transporter. High-resolution receptor-binding studies showed that co-expression of membrane-bound SLC1A5 with hACE2 predicted SARS-CoV-2 binding and entry better than hACE2 expression alone. Accordingly, SLC1A5 depletion reduces SARS-CoV-2 binding and entry. Notably, the Omicron variant is more efficient in binding hACE2 sites, but equally sensitive to SLC1A5 downregulation. We propose a method for mapping functional SARS-CoV-2 receptors in vivo. We confirm the existence of hACE2 co-factors that may contribute to differential sensitivity of cells to infection.
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:Universal vaccines cross-protecting against sarbecoviruses including SARS-CoV-2 are in great need under continuous emergence of SARS-CoV-2 variants and potential novel coronavirus. Nanoparicle vaccines displaying mosaic receptor-binding domains (RBDs) or spike (S) proteins from SARS-CoV-2 and other sarbecoviruses were used for preparedness to emergent zoonotic outbreak. Here, we describe a self-assembling nanoparticle using lumazine synthase (LuS) as the scaffold to display RBDs from different sarbecoviruses. The mosaic LuS-RBD vaccines induced cross-reactive binding and neutralizing antibody responses to sarbecoviruses. Single B cell sequencing revealed that mosaic LuS-RBD elicited B-cell receptor (BCR) repertoire using an immunodominant germline gene pair of IGHV14-3: IGKV14-111 in mice. Most of the tested IGHV14-3: IGKV14-111 monoclonal antibodies (mAbs) are broadly cross-reactive to the clade 1a, 1b and 3 sarbecoviruses. By antibody binning and cryo-electron microscopy, we determined a reprensentative IGHV14-3: IGKV14-111 mAb, M2-7, bound to an conserved epitope on RBD largely overlapping with a pan-sarbecovirus mAb S2H97, which suggested that mosaic nanoparticles expended B cells recognizing the common epitopes shared by different clades of sarbecoviruses. These results provide immunological insights into the cross-reactive responses elicited by mosaic nanoparticle against emerging sarbecoviruses.
Project description:We used SPIDER to examine the cell-surface receptors for specific ligands while these receptors were in their native membranes within intact cells in culture. Here we coupled the SPIDER assay with biotinylated RBD of the Omicron Variant of SARS-CoV-2 and biotinylated RBD of SARS-CoV-2. Then we performed mass spectrometry strategy to identify novel binding proteins on the surface of VERO E6,Calu-3,and H1299 cells.
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:Since the start of the coronavirus disease-2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused more than 2 million deaths worldwide. Many vaccines have been deployed to date; however, the continual evolution of the viral receptor binding domain (RBD) has recently challenged their efficacy. In particular, SARS-CoV-2 variants originating in South Africa (B.1.351) and the U.K. (B.1.1.7) have reduced plasma neutralization activity and crippled antibody cocktails that received emergency use authorization1-3. Whereas vaccines can be updated periodically to account for emerging variants, complementary strategies are urgently needed to overcome viral escape. One potential alternative are camelid VHHs (also known as nanobodies), which can access conserved epitopes often hidden to conventional antibodies4-6. We here isolate anti-RBD nanobodies from llamas and mice engineered to produce VHHs from alpacas, dromedaries and camels. Through neutralization assays and cryo-electron microscopy we identify two “nanomouse” VHHs that circumvent RBD antigenic drift by recognizing a domain conserved in coronaviruses, away from the ACE2 binding motif. Conversely, llama nanobodies recognize the RBD-ACE2 interphase and as monomers they are ineffective against E484K or N501Y substitutions. Notably, as homotrimers those same VHHs neutralize RBD variants with ultrahigh (pM) affinity, rivaling the most potent antibodies produced to date against SARS-CoV-2. We conclude that multivalent nanobodies can avert SARS-CoV-2 escape mutants and thus they represent promising tools to prevent COVID-19 mortality when vaccines are compromised.
Project description:Memory B cells play a fundamental role in host defenses against viruses. This dataset aimed at understanding the recruitment and remodeling of the memory B cell repertoire in the context of BA.1-breakthrough infection in BNT162b2 mRNA vaccinated individuals. All four donors enrolled in the study had received a booster (3rd dose) of BNT162b2 mRNA vaccine and had no history of prior SARS-CoV-2 infection. All four experienced a documented breakthrough infection between 12/24/2021 and 01/30/2022 when BA.1 was responsible for > 85% of SARS-CoV-2 infections in France. All donors were sampled at Henri Mondor University Hospital (AP-HP, Paris France), and samples used for scRNA-seq were collected shortly after breakthrough infection (PO_M0 samples; between day 7 and day 18) and 5 to 6 months after infection (PO_M6 samples; between day 152 and day 173). Clinical and biological characteristics of these patients are summarized in the Patient_information.csv file. For each sample, an initial pool of 50.000 total peripheral CD3-CD14-CD56- CD19+ IgD- cells was always sorted and afterward, to enrich for cells of interest, only CD19+CD38low antibody secreting cells (ASCs), CD19hi IgD+ cells and SARS-CoV-2 Spike/RBD PE/tetramer positive B cells were sorted, leading to approximately 55000-60000 total sorted cells per sample. Sorted cells were then counted and up to 20 000 cells were loaded in the 10x Chromium Controller to generate single-cell gel-beads in emulsion. The scRNA-seq libraries for gene expression (mRNA), ADT and VDJ BCR libraries were generated using Chromium Next GEM Single Cell V(D)J Reagent Kit v.1.1 with Feature Barcoding (10x Genomics) according to the manufacturer’s protocol. PBMCs were initially isolated from venous blood samples via standard density gradient centrifugation and used after cryopreservation at -150°C. PBMCs were thawed using RPMI-1640 (Gibco) 10% FBS, washed twice and approximately 15x106 cells were then resuspended in 100µL PBS 2%FBS and incubated for 40 minutes at 4°C with a decoy tetramer (biotinylated Bovine Serum albumin coupled with BV785 streptavidin) and Hu-1 Spike, BA.1 Spike, Hu-1 RBD and BA.1 RBD tetramers (constructed using PE-labelled TotalSeqC® streptavidin with different barcodes for each individual antigens (see feature_reference.csv.gz files).). Cells were washed, resuspended in 100µL PBS 2%FBS and stained with a cocktail of fluorochrome conjugated (CD3, CD14 both APC-H7 at 1:100 each; CD15 and CD56 BV785 at 1:100 each, CD19 PECF594 at 1:100, IgD FITC at 1:100, CD38 PercP-Cy5.5 at 1:100) and TotalSeqC® (CD38, CD27, CD71, CD21, CD11c, CD39, FCRL5, CD95 all at 1:40 (all obtained from BioLegend)) antibodies for 40 minutes on ice. Viable cells were identified using a LIVE/DEAD Fixable Aqua Dead Cell Stain Kit (Thermo Fisher Scientific, 1:200) incubated with conjugated antibodies. Two distinct sorts were performed for each donor: one at the early time-point (PO_M0) and one at the 6 months’ time-point (PO_M6).
Project description: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.