ABSTRACT
The emergence of a new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents an urgent public health crisis. Without available targeted therapies, treatment options remain limited for COVID-19 patients. Using medicinal chemistry and rational drug design strategies, we identify a 2-phenyl-1,2-benzoselenazol-3-one class of compounds targeting the SARS-CoV-2 main protease (Mpro). FRET-based screening against recombinant SARS-CoV-2 Mpro identified six compounds that inhibit proteolysis with nanomolar IC50 values. Preincubation dilution experiments and molecular docking determined that the inhibition of SARS-CoV-2 Mpro can occur by either covalent or noncovalent mechanisms, and lead E04 was determined to inhibit Mpro competitively. Lead E24 inhibited viral replication with a nanomolar EC50 value (844 nM) in SARS-CoV-2-infected Vero E6 cells and was further confirmed to impair SARS-CoV-2 replication in human lung epithelial cells and human-induced pluripotent stem cell-derived 3D lung organoids. Altogether, these studies provide a structural framework and mechanism of Mpro inhibition that should facilitate the design of future COVID-19 treatments.
Subject(s)
Antiviral Agents/pharmacology , Benzothiazoles/pharmacology , Coronavirus 3C Proteases/antagonists & inhibitors , Cysteine Proteinase Inhibitors/pharmacology , Drug Discovery , SARS-CoV-2/drug effects , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Benzothiazoles/chemistry , COVID-19/metabolism , Chlorocebus aethiops , Coronavirus 3C Proteases/isolation & purification , Coronavirus 3C Proteases/metabolism , Crystallography, X-Ray , Cysteine Proteinase Inhibitors/chemical synthesis , Cysteine Proteinase Inhibitors/chemistry , Dose-Response Relationship, Drug , Fluorescence Resonance Energy Transfer , Humans , Microbial Sensitivity Tests , Molecular Docking Simulation , Molecular Structure , SARS-CoV-2/enzymology , Vero Cells , Virus Replication/drug effects , COVID-19 Drug TreatmentABSTRACT
COVID-19 is a transmissible respiratory disease caused by a novel coronavirus, SARS-CoV-2, and has become a global health emergency. There is an urgent need for robust and practical in vitro model systems to investigate viral pathogenesis. Here, we generated human induced pluripotent stem cell (iPSC)-derived lung organoids (LORGs), cerebral organoids (CORGs), neural progenitor cells (NPCs), neurons, and astrocytes. LORGs containing epithelial cells, alveolar types 1 and 2, highly express ACE2 and TMPRSS2 and are permissive to SARS-CoV-2 infection. SARS-CoV-2 infection induces interferons, cytokines, and chemokines and activates critical inflammasome pathway genes. Spike protein inhibitor, EK1 peptide, and TMPRSS2 inhibitors (camostat/nafamostat) block viral entry in LORGs. Conversely, CORGs, NPCs, astrocytes, and neurons express low levels of ACE2 and TMPRSS2 and correspondingly are not highly permissive to SARS-CoV-2 infection. Infection in neuronal cells activates TLR3/7, OAS2, complement system, and apoptotic genes. These findings will aid in understanding COVID-19 pathogenesis and facilitate drug discovery.
Subject(s)
Brain/virology , COVID-19/virology , Induced Pluripotent Stem Cells/virology , Lung/virology , Neural Stem Cells/virology , Organoids/virology , SARS-CoV-2/pathogenicity , Apoptosis/physiology , Brain/metabolism , COVID-19/metabolism , Cells, Cultured , Complement System Proteins/metabolism , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Induced Pluripotent Stem Cells/metabolism , Inflammation/metabolism , Inflammation/virology , Lung/metabolism , Neural Stem Cells/metabolism , Neurons/metabolism , Neurons/virology , Organoids/metabolism , Serine Endopeptidases/metabolism , Signal Transduction/physiology , Stem Cells/metabolism , Stem Cells/virologyABSTRACT
Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 and has spread across the globe. SARS-CoV-2 is a highly infectious virus with no vaccine or antiviral therapy available to control the pandemic; therefore, it is crucial to understand the mechanisms of viral pathogenesis and the host immune responses to SARS-CoV-2. SARS-CoV-2 is a new member of the betacoronavirus genus like other closely related viruses including SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV). Both SARS-CoV and MERS-CoV have caused serious outbreaks and epidemics in the past eighteen years. Here, we report that one of the interferon-stimulated genes (ISGs), cholesterol 25-hydroxylase (CH25H), is induced by SARS-CoV-2 infection in vitro and in COVID-19-infected patients. CH25H converts cholesterol to 25-hydrocholesterol (25HC) and 25HC shows broad anti-coronavirus activity by blocking membrane fusion. Furthermore, 25HC inhibits USA-WA1/2020 SARS-CoV-2 infection in lung epithelial cells and viral entry in human lung organoids. Mechanistically, 25HC inhibits viral membrane fusion by activating the ER-localized acyl-CoA:cholesterol acyltransferase (ACAT) which leads to the depletion of accessible cholesterol from the plasma membrane. Altogether, our results shed light on a potentially broad antiviral mechanism by 25HC through depleting accessible cholesterol on the plasma membrane to suppress virus-cell fusion. Since 25HC is a natural product with no known toxicity at effective concentrations, it provides a potential therapeutic candidate for COVID-19 and emerging viral diseases in the future.