Project description:The ongoing COVID-19 pandemic represents an unprecedented global health crisis. Here, we report the identification of a synthetic nanobody (sybody) pair, Sb#15 and Sb#68, that can bind simultaneously to the SARS-CoV-2 spike-RBD and efficiently neutralize pseudotyped and live-viruses by interfering with ACE2 interaction. Cryo-EM confirms that Sb#15 and Sb#68 engage two spatially-discrete epitopes, influencing rational design of bispecific and tri-bispecific fusion constructs that exhibit up to 100- and 1000-fold increase in neutralization potency, respectively. Cryo-EM of the sybody-spike complex additionally reveals a novel up-out RBD conformation. While resistant viruses emerge rapidly in the presence of single binders, no escape variants are observed in presence of the bispecific sybody. The multivalent bispecific constructs further increase the neutralization potency against globally-circulating SARS-CoV-2 variants of concern. Our study illustrates the power of multivalency and biparatopic nanobody fusions for the potential development of therapeutic strategies that mitigate the emergence of new SARS-CoV-2 escape mutants.
Project description:Despite the efficacy of antiviral drug repositioning, convalescent plasma (CP), and the currently available vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the worldwide coronavirus disease 2019 (COVID-19) pandemic is still challenging because of the ongoing emergence of certain new SARS-CoV-2 strains known as variants of concern (VOCs). Mutations occurring within the viral genome, characterized by these new emerging VOCs, confer on them the ability to efficiently resist and escape natural and vaccine-induced humoral and cellular immune responses. Consequently, these VOCs have enhanced infectivity, increasing their stable spread in a given population with an important fatality rate. While the humoral immune escape process is well documented, the evasion mechanisms of VOCs from cellular immunity are not well elaborated. In this review, we discussed how SARS-CoV-2 VOCs adapt inside host cells and escape anti-COVID-19 cellular immunity, focusing on the effect of specific SARS-CoV-2 mutations in hampering the activation of CD8+ T-cell immunity.
Project description:The global pandemic of the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), places a heavy burden on global public health. Four SARS-CoV-2 variants of concern including B.1.1.7, B.1.351, B.1.617.2, and P.1, and two variants of interest including C.37 and B.1.621 have been reported to have potential immune escape, and one or more mutations endow them with worrisome epidemiologic, immunologic, or pathogenic characteristics. This review introduces the latest research progress on SARS-CoV-2 variants of interest and concern, key mutation sites, and their effects on virus infectivity, mortality, and immune escape. Moreover, we compared the effects of various clinical SARS-CoV-2 vaccines and convalescent sera on epidemic variants, and evaluated the neutralizing capability of several antibodies on epidemic variants. In the end, SARS-CoV-2 evolution strategies in different transmission stages, the impact of different vaccination strategies on SARS-CoV-2 immune escape, antibody therapy strategies and COVID-19 epidemic control prospects are discussed. This review will provide a systematic and comprehensive understanding of the secret of SARS-CoV-2 variants of interest/concern and immune escape.
Project description:BackgroundAs of November 25th 2021, four SARS-CoV - 2 variants of concern (VOC: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2)) have been detected. Variable degrees of increased transmissibility of the VOC have been documented, with potential implications for hospital and health system capacity and control measures. This rapid review aimed to provide a synthesis of evidence related to health system responses to the emergence of VOC worldwide.MethodsSeven databases were searched up to September 27, 2021, for terms related to VOC. Titles, abstracts, and full-text documents were screened independently by two reviewers. Data were extracted independently by two reviewers using a standardized form. Studies were included if they reported on at least one of the VOC and health system outcomes.ResultsOf the 4877 articles retrieved, 59 studies were included, which used a wide range of designs and methods. Most of the studies reported on Alpha, and all except two reported on impacts for capacity planning related to hospitalization, intensive care admissions, and mortality. Most studies (73.4%) observed an increase in hospitalization, but findings on increased admission to intensive care units were mixed (50%). Most studies (63.4%) that reported mortality data found an increased risk of death due to VOC, although health system capacity may influence this. No studies reported on screening staff and visitors or cohorting patients based on VOC.ConclusionWhile the findings should be interpreted with caution as most of the sources identified were preprints, evidence is trending towards an increased risk of hospitalization and, potentially, mortality due to VOC compared to wild-type SARS-CoV - 2. There is little evidence on the need for, and the effect of, changes to health system arrangements in response to VOC transmission.
Project description:COVID-19, an infectious disease caused by the SARS-CoV-2 virus, emerged globally in early 2020 and has remained a serious public health issue. To date, although several preventative vaccines have been approved by FDA and EMA, vaccinated individuals increasingly suffer from breakthrough infections. Therapeutic antibodies may provide an alternative strategy to neutralize viral infection and treat serious cases; however, the clinical data and our experiments show that some FDA-approved monoclonal antibodies lose function against COVID-19 variants such as Omicron. Therefore, in this study, we present a novel therapeutic agent, SI-F019, an ACE2-Fc fusion protein whose neutralization efficiency is not compromised, but actually strengthened, by the mutations of dominant variants including Omicron. Comprehensive biophysical analyses revealed the mechanism of increased inhibition to be enhanced interaction of SI-F019 with all the tested spike variants, in contrast to monoclonal antibodies which tended to show weaker binding to some variants. The results imply that SI-F019 may be a broadly useful agent for treatment of COVID-19.
Project description:The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic have led to the development of various diagnostic tests. The OraSure InteliSwab™ COVID-19 Rapid Test is a recently developed and FDA emergency use-authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern such as Omicron. In this study, the sensitivity of the OraSure InteliSwab™ Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined. The OraSure InteliSwab™ Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants, with recorded limits of detection ranging between 3.77 × 105 and 9.13 × 105 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the six VOCs. Ultimately, the OraSure InteliSwab™ COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.
Project description:The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic has led to the development of various diagnostic tests. The OraSure InteliSwab ® COVID-19 Rapid Test is a recently developed and FDA emergency use authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern like Omicron. In this study, the sensitivity of the OraSure InteliSwab ® Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined. The OraSure InteliSwab ® Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants with recorded limits of detection ranging between 3.77 × 10 5 and 9.13 × 10 5 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the 6 VOCs. Ultimately, the OraSure InteliSwab ® COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.
Project description:SARS-CoV-2 variants of concern (VOCs) that increase transmission or disease severity or reduce diagnostic or vaccine efficacy continue to emerge across the world. Current methods available to rapidly detect these can be resource intensive and thus sub-optimal for large-scale deployment needed during a pandemic response. Here, we describe a CRISPR-based assay that detects mutations in spike gene CRISPR PAM motif or seed regions to identify a pan-specific VOC single-nucleotide polymorphism (SNP)) ((D614G) and Alpha- and Delta-specific (S982A and D950N) SNPs. This assay exhibits good diagnostic sensitivity and strain specificity with nasal swabs and is designed for use in laboratory and point-of-care settings. This should enable rapid, high-throughput VOC identification required for surveillance and characterization efforts to inform clinical and public health decisions. Furthermore, the assay can be adapted to target similar SNPs associated with emerging SARS-CoV-2 VOCs, or other rapidly evolving viruses.