ABSTRACT
MS is a powerful methodology for chemical screening to directly quantify substrates and products of enzymes, but its low throughput has been an issue. Recently, an acoustic liquid-handling apparatus (Echo®) used for rapid nano-dispensing has been coupled to a high-sensitivity mass spectrometer to create the Echo® MS system, and we applied this system to screening of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 3CL protease inhibitors. Primary screening of 32033 chemical samples was completed in 12 h. Among the hits showing selective, dose-dependent 3CL-inhibitory activity, 8 compounds showed antiviral activity in cell-based assay.
Subject(s)
COVID-19 Drug Treatment , Protease Inhibitors , Acoustics , High-Throughput Screening Assays/methods , Humans , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , SARS-CoV-2ABSTRACT
Potent neutralizing SARS-CoV-2 antibodies often target the spike protein receptor-binding site (RBS), but the variability of RBS epitopes hampers broad neutralization of multiple sarbecoviruses and drifted viruses. Here, using humanized mice, we identified an RBS antibody with a germline VH gene that potently neutralized SARS-related coronaviruses, including SARS-CoV and SARS-CoV-2 variants. X-ray crystallography revealed coordinated recognition by the heavy chain of non-RBS conserved sites and the light chain of RBS with a binding angle mimicking the angiotensin-converting enzyme 2 (ACE2) receptor. The minimum footprints in the hypervariable region of RBS contributed to the breadth of neutralization, which was enhanced by immunoglobulin G3 (IgG3) class switching. The coordinated binding resulted in broad neutralization of SARS-CoV and emerging SARS-CoV-2 variants of concern. Low-dose therapeutic antibody treatment in hamsters reduced the virus titers and morbidity during SARS-CoV-2 challenge. The structural basis for broad neutralizing activity may inform the design of a broad spectrum of therapeutics and vaccines.
Subject(s)
Broadly Neutralizing Antibodies/immunology , Cross Reactions/immunology , SARS-CoV-2/immunology , Animals , Betacoronavirus/immunology , Binding Sites, Antibody , Broadly Neutralizing Antibodies/chemistry , Broadly Neutralizing Antibodies/therapeutic use , COVID-19/prevention & control , COVID-19/therapy , COVID-19/virology , Cricetinae , Humans , Immunoglobulin Class Switching , Immunoglobulin Fab Fragments/chemistry , Immunoglobulin Fab Fragments/metabolism , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Mice , Protein Domains , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolismABSTRACT
Antiviral treatments targeting the coronavirus disease 2019 are urgently required. We screened a panel of already approved drugs in a cell culture model of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and identified two new agents having higher antiviral potentials than the drug candidates such as remdesivir and chroloquine in VeroE6/TMPRSS2 cells: the anti-inflammatory drug cepharanthine and human immunodeficiency virus protease inhibitor nelfinavir. Cepharanthine inhibited SARS-CoV-2 entry through the blocking of viral binding to target cells, while nelfinavir suppressed viral replication partly by protease inhibition. Consistent with their different modes of action, synergistic effect of this combined treatment to limit SARS-CoV-2 proliferation was highlighted. Mathematical modeling in vitro antiviral activity coupled with the calculated total drug concentrations in the lung predicts that nelfinavir will shorten the period until viral clearance by 4.9 days and the combining cepharanthine/nelfinavir enhanced their predicted efficacy. These results warrant further evaluation of the potential anti-SARS-CoV-2 activity of cepharanthine and nelfinavir.