Project description:The spike S of SARS-CoV-2 recognizes ACE2 on the host cell membrane to initiate entry. Soluble decoy receptors, in which the ACE2 ectodomain is engineered to block S with high affinity, potently neutralize infection and, due to close similarity with the natural receptor, hold out the promise of being broadly active against virus variants without opportunity for escape. Here, we directly test this hypothesis. Using deep mutagenesis, we find that the ACE2-binding surface of the SARS-CoV-2 spike tolerates high mutational diversity, which may act as a source for resistance to therapeutics. However, saturation mutagenesis of the receptor-binding domain (RBD) followed by in vitro selection, with wild type ACE2 and the engineered decoy competing for binding sites, failed to find S mutants that discriminate in favor of the wild type receptor. We conclude that resistance to engineered decoys will be rare.
Project description:Here, we have used a SARS-naïve, bovine ultralong CDRH3 library to isolate a bovine paratope that engages the SARS-CoV and SARS-CoV-2 receptor-binding domain (RBD). This scFv (B9-scFv) neutralises viruses pseudo-typed with SARS-CoV Spike protein. Using differential hydrogen-deuterium exchange mass spectrometry and site-directed mutagenesis, we demonstrate that this CDRH3 recognises a conserved, cryptic epitope.
Project description:The rapid and escalating spread of SARS coronavirus 2 (SARS-CoV-2) poses an immediate public health emergency, and no approved therapeutics or vaccines are currently available. The viral spike protein S binds membrane-tethered ACE2 on host cells in the lungs to initiate molecular events that ultimately release the viral genome intracellularly. The extracellular protease domain of ACE2 inhibits cell entry of both SARS and SARS-2 coronaviruses by acting as a soluble decoy for receptor binding sites on S, and is a promising candidate for therapeutic and prophylactic development. Using deep mutagenesis, variants of ACE2 are identified with increased binding to the receptor binding domain of S at a cell surface. Mutations are found across the protein-protein interface and also at buried sites where they are predicted to enhance folding and presentation of the interaction epitope. The mutational landscape offers a preliminary blueprint for engineering high affinity ACE2 receptors to meet this unprecedented challenge.
Project description:There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2) which causes the disease COVID-19. SARS-CoV-2 spike (S)-protein binds ACE2, and in concert with host proteases, principally TMPRSS2, promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues, and the factors that regulate ACE2 expression, remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 amongst tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discover that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells, and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection.
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.
Project description:In this study a gene expression (i.e., RNAseq) analysis was performed in HEK293T-ACE2 cellular model upon infection with viral particle belonging to VOC Delta (MOI: 0.026) for 24 hours in order to have a global picture of the transcriptome landscape in response to early phase of infection of SARS-CoV-2 ( VOC Delta infection and to evaluate the role of Ca2+ in HEK293-ACE2 cellular model and transfer to homeostasis in SARS-COV-2 patients (by Pasqualino de Antonellis1-2* and Veronica Ferrucci 1-2* (first authors) et al. and Massimo Zollo1-2# (corresponding author). Manuscript in preparation 2022 July 15th 2022. Short title "ATP2B1 (PMCA1), regulated by FOXO3, influences susceptibility to severe COVID19".
Project description:Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the recent global COVID-19 outbreak, which led to a public health emergency. Entry of SARS-CoV-2 into human cells is dependent on the SARS-CoV receptor, angiotensin converting enzyme 2 (ACE2) receptor, and cathepsin. Cathepsin degrades the spike protein (S protein), which results in the entry of viral nucleic acid into the human host cell. Methods: We explored the susceptibility of the central nervous system (CNS) to SARS-CoV-2 infection using single-cell transcriptome analysis of glioblastoma. Results: The results showed that ACE2 expression is relatively high in endothelial cells (ECs), bone marrow mesenchymal stem cells (BMSCs), and neural precursor cells (NPCs). Cathepsin B (Cat B) and cathepsin (Cat L) were also strongly expressed in various cell clusters within the glioblastoma microenvironment. Immunofluorescence staining of glioma and normal brain tissue chips further confirmed that ACE2 expression co-localized with CD31, CD73, and nestin, which confirmed the susceptibility to SARS-CoV-2 of nervous system cells, including ECs, BMSCs and NPCs, from clinical specimens. Conclusions: These findings reveal the mechanism of SARS-CoV-2 neural invasion and suggest that special attention should be paid to SARS-CoV-2-infected patients with neural symptoms, especially those who suffered a glioma.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19), which, since 2019 in China, has rapidly become a worldwide pandemic. The aggressiveness and global spread were enhanced by the many SARS-CoV-2 variants that have been isolated up to now. These mutations affect mostly the viral glycoprotein Spike (S), the capsid protein mainly involved in the early stages of viral entry processes, through the recognition of specific receptors on the host cell surface. In particular, the subunit S1 of the Spike glycoprotein contains the Receptor Binding Domain (RBD) and it is responsible for the interaction with the angiotensin-converting enzyme 2 (ACE2). Although ACE2 is the primary Spike host receptor currently studied, it has been demonstrated that SARS-CoV-2 is also able to infect cells expressing low levels of ACE2, indicating that the virus may have alternative receptors on the host cells. The identification of the alternative receptors can better elucidate the pathogenicity and the tropism of SARS-CoV-2. Therefore, we investigated the Spike S1 interactomes, starting from host membrane proteins of non-pulmonary cell lines, such as human kidney (HK-2), normal colon (NCM460D), and colorectal adenocarcinoma (Caco-2). We employed an affinity purification-mass spectrometry (AP-MS) to pull down, from the membrane protein extracts of all cell lines, the protein partners of the recombinant form of the Spike S1 domain. The purified interactors were identified by a shotgun proteomics approach. The lists of S1 potential interacting proteins were then clusterized according to cellular localization, biological processes, and pathways, highlighting new possible S1 intracellular functions, crucial not only for the entrance mechanisms but also for viral replication and propagation processes.
Project description:Here we identify halofuginone, a Prolyl-tRNA Synthetase (PRS) inhibitors as a potent inhibitors of SARS-CoV-2 cellular entry and viral replication. To infect the host cell, the SARS-CoV-2 spike protein interacts with cell surface heparan sulfate (HS) and angiotensin-converting enzyme 2 (ACE2) through its Receptor Binding Domain. Removal of cell surface HS or blockade of HS biosynthesis represents a promising clinical target for treatment of SARS-CoV-2. In vitro studies confirm that halofuginone and PRS inhibitors prevent HS biosynthesis and thereby HS cell surface presentation and Spike protein binding. Halofuginone also suppresses authentic SARS-CoV-2 infection by inhibiting PRS activity, which decreases the translation efficiency of proline-rich HS biosynthetic enzymes and essential SARS-CoV-2 proteins after infection. Thus, halofuginone inhibits SARS-CoV-2 at both attachment and post-entry steps and blocks SARS-CoV-2 infection of human lung airway epithelial cells at low nanomolar concentrations. These findings support the use of halofuginone, an orally bioavailable anti-fibrotic and anti-inflammatory compound with encouraging clinical phase 1 safety data, as an antiviral drug to prevent SARS-CoV-2 infection.
Project description:Here we identify halofuginone, a Prolyl-tRNA Synthetase (PRS) inhibitors as a potent inhibitors of SARS-CoV-2 cellular entry and viral replication. To infect the host cell, the SARS-CoV-2 spike protein interacts with cell surface heparan sulfate (HS) and angiotensin-converting enzyme 2 (ACE2) through its Receptor Binding Domain. Removal of cell surface HS or blockade of HS biosynthesis represents a promising clinical target for treatment of SARS-CoV-2. In vitro studies confirm that halofuginone and PRS inhibitors prevent HS biosynthesis and thereby HS cell surface presentation and Spike protein binding. Halofuginone also suppresses authentic SARS-CoV-2 infection by inhibiting PRS activity, which decreases the translation efficiency of proline-rich HS biosynthetic enzymes and essential SARS-CoV-2 proteins after infection (data not provided here). Thus, halofuginone inhibits SARS-CoV-2 at both attachment and post-entry steps and blocks SARS-CoV-2 infection of human lung airway epithelial cells at low nanomolar concentrations. These findings support the use of halofuginone, an orally bioavailable anti-fibrotic and anti-inflammatory compound with encouraging clinical phase 1 safety data, as an antiviral drug to prevent SARS-CoV-2 infection.