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:We have developed a SARS-CoV-2 PsV system that expresses the spike protein on the viral surface and carries spike protein genomic sequences, enabling this pseudovirus to activate infection signaling pathways through ACE2 and stimulate intracellular spike protein gene expression. To understand the impact of SARS-CoV-2 on hematopoietic system, we infected heman HSPCs with Omicron PsV and analyzed changes in transcriptome
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:The continuous evolution of SARS-CoV-2 poses global health challenges. A safe, rapid, and versatile method for assessing functions of Spike protein mutations in ACE2 receptor binding and immune evasion would be highly valuable. To address this, we engineered a transcription- and replication-competent virus-like particle (trVLP) derived from the Sindbis virus, pseudotyped with the SARS-CoV-2 receptor binding domain (RBD). This trVLP exclusively propagates in BHK-21 cell engineered to express both RNA replicase and human ACE2, providing a controllable, safe model of SARS-CoV-2 RBD-ACE2 interaction mediated virus entry. The system enables characterization of RBD interactions with ACE2 from various mammalian hosts, demonstrating its utility for studying host-virus interactions. By leveraging the evolutionary capability of trVLP mediated by error-prone RNA replication, we screened for RBD variants that evade the antibody-mediated inhibition of cell entry. Together, these findings underscore the utility of the trVLP as a safe, rapid, and flexible platform for dissecting SARS-CoV-2 RBD evolution and identifying key adaptive mutations with implications for surveillance and countermeasure development.
Project description:The continuous evolution of SARS-CoV-2 poses global health challenges. A safe, rapid, and versatile method for assessing functions of Spike protein mutations in ACE2 receptor binding and immune evasion would be highly valuable. To address this, we engineered a transcription- and replication-competent virus-like particle (trVLP) derived from the Sindbis virus, pseudotyped with the SARS-CoV-2 receptor binding domain (RBD). This trVLP exclusively propagates in BHK-21 cell engineered to express both RNA replicase and human ACE2, providing a controllable, safe model of SARS-CoV-2 RBD-ACE2 interaction mediated virus entry. The system enables characterization of RBD interactions with ACE2 from various mammalian hosts, demonstrating its utility for studying host-virus interactions. By leveraging the evolutionary capability of trVLP mediated by error-prone RNA replication, we screened for RBD variants that evade the antibody-mediated inhibition of cell entry. Together, these findings underscore the utility of the trVLP as a safe, rapid, and flexible platform for dissecting SARS-CoV-2 RBD evolution and identifying key adaptive mutations with implications for surveillance and countermeasure development.
Project description:The continuous evolution of SARS-CoV-2 poses global health challenges. A safe, rapid, and versatile method for assessing functions of Spike protein mutations in ACE2 receptor binding and immune evasion would be highly valuable. To address this, we engineered a transcription- and replication-competent virus-like particle (trVLP) derived from the Sindbis virus, pseudotyped with the SARS-CoV-2 receptor binding domain (RBD). This trVLP exclusively propagates in BHK-21 cell engineered to express both RNA replicase and human ACE2, providing a controllable, safe model of SARS-CoV-2 RBD-ACE2 interaction mediated virus entry. The system enables characterization of RBD interactions with ACE2 from various mammalian hosts, demonstrating its utility for studying host-virus interactions. By leveraging the evolutionary capability of trVLP mediated by error-prone RNA replication, we screened for RBD variants that evade the antibody-mediated inhibition of cell entry. Together, these findings underscore the utility of the trVLP as a safe, rapid, and flexible platform for dissecting SARS-CoV-2 RBD evolution and identifying key adaptive mutations with implications for surveillance and countermeasure development.
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:The coronavirus disease 2019 (COVID-19) pandemic, initiated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread worldwide. The entry of SARS-CoV-2 into human cells relies on the interaction between the receptor- binding domain (RBD) of the spike protein on the surface of the virus and the angiotensin-converting enzyme 2 (ACE2) receptor on the surface of human cells. Consequently, disrupting the interaction between the spike protein and ACE2 is a promising strategy for preventing SARS-CoV-2 infection and treating SARS-CoV-2 infected patients. To discover potential drugs for SARS-CoV-2 from traditional Chinese medicines (TCMs), we established a plat-form combining ACE2-conjugated magnetic particles, a spike protein, a C18 plate, and MALDI-TOF for rapid screening of potential TCM candidates for SARS-CoV-2. After screening over 100 TCMs, some were found to effectively inhibit the binding interaction between ACE2 and spike proteins. We further identified three active compounds in these TCMs that could inhibit the binding between ACE2 and the spike protein of the Omicron variant. These three compounds also showed potent activity in blocking viral entry in a SARS-CoV-2 viral pseudo-particles (Vpp) cell-based assay.