ABSTRACT Coronavirus disease 2019 (COVID-19) caused by the emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has set off a global pandemic. There is an urgent unmet need for safe, affordable, and effective therapeutics against COVID-19. In this regard, drug repurposing is considered as a promising approach. We assessed the compounds that affect the endosomal acidic environment by applying human angiotensin-converting enzyme 2 (hACE2)- expressing cells infected with a SARS-CoV-2 spike (S) protein-pseudotyped HIV reporter virus and identified that obatoclax resulted in the strongest inhibition of S protein-mediated virus entry. The potent antiviral activity of obatoclax at nanomolar concentrations was confirmed in different human lung and intestinal cells infected with the SARS-CoV-2 pseudotype system as well as clinical virus isolates. Furthermore, we uncovered that obatoclax executes a double-strike against SARS-CoV-2. It prevented SARS-CoV-2 entry by blocking endocytosis of virions through diminished endosomal acidification and the corresponding inhibition of the enzymatic activity of the endosomal cysteine protease cathepsin L. Additionally, obatoclax impaired the SARS-CoV-2 S-mediated membrane fusion by targeting the MCL-1 protein and reducing furin protease activity. In accordance with these overarching mechanisms, obatoclax blocked the virus entry mediated by different S proteins derived from several SARS-CoV-2 variants of concern such as, Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2). Taken together, our results identified obatoclax as a novel effective antiviral compound that keeps SARS-CoV-2 at bay by blocking both endocytosis and membrane fusion. Our data suggested that obatoclax should be further explored as a clinical drug for the treatment of COVID-19.
【저자키워드】 SARS-CoV-2, endocytosis, membrane fusion, Obatoclax, MCL-1, 【초록키워드】 COVID-19, Treatment, HIV, Coronavirus disease 2019, coronavirus, S protein, B.1.351, SARS-CoV-2 variant, Delta, B.1.617.2, antiviral activity, virus, hACE2, global pandemic, Protein, B.1.1.7, pseudotype, human lung, virus entry, Endosomal acidification, Beta, mechanisms, reporter, SARS-CoV-2 spike, furin protease, Concentration, Safe, cathepsin L, unmet need, acute respiratory syndrome, set off, enzymatic activity, SARS-CoV-2 entry, Compound, cysteine protease, human Angiotensin-converting enzyme, Acidic, virion, Affect, Antiviral compound, approach, effective, Cell, blocked, caused, reducing, suggested, prevented, expressing, clinical virus isolates, intestinal cell, the SARS-CoV-2, 【제목키워드】 furin, in vitro, Endosomal acidification, SARS-CoV-2 entry, inhibit,