The Anticoagulant Nafamostat Potently Inhibits SARS-CoV-2 S Protein-Mediated Fusion in a Cell Fusion Assay System and Viral Infection In Vitro in a Cell-Type-Dependent Manner

• Published in: Viruses Vol. 12; no. 6; p. 629
• Main Authors: Yamamoto, Mizuki, Kiso, Maki, Sakai-Tagawa, Yuko, Iwatsuki-Horimoto, Kiyoko, Imai, Masaki, Takeda, Makoto, Kinoshita, Noriko, Ohmagari, Norio, Gohda, Jin, Semba, Kentaro, Matsuda, Zene, Kawaguchi, Yasushi, Kawaoka, Yoshihiro, Inoue, Jun-ichiro
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 10.06.2020; MDPI AG
• Subjects: Angiotensin-Converting Enzyme 2; Angiotensin-Converting Enzyme Inhibitors - pharmacology; Animals; anticoagulants; Anticoagulants - pharmacology; Betacoronavirus - drug effects; Betacoronavirus - metabolism; blood; cell fusion; Cell Line; Chlorocebus aethiops; Communication; Coronavirus Infections - drug therapy; Coronavirus Infections - virology; COVID-19; COVID-19 infection; disseminated intravascular coagulation; etiological agents; fusion inhibitor; Gabexate - analogs & derivatives; Gabexate - pharmacology; Guanidines - pharmacology; HEK293 Cells; Humans; intravenous injection; lungs; median effective concentration; Middle East respiratory syndrome coronavirus; Pandemics; peptidyl-dipeptidase A; Peptidyl-Dipeptidase A - metabolism; pneumonia; Pneumonia, Viral - drug therapy; Pneumonia, Viral - virology; SARS-CoV-2; Serine Endopeptidases - metabolism; serine proteinases; Severe acute respiratory syndrome coronavirus 2; Spike Glycoprotein, Coronavirus - antagonists & inhibitors; Spike Glycoprotein, Coronavirus - metabolism; TMPRSS2; Vero Cells; Virus Internalization - drug effects; TMPRSS2; SARS-CoV-2; fusion inhibitor
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v12060629

Although infection by SARS-CoV-2, the causative agent of coronavirus pneumonia disease (COVID-19), is spreading rapidly worldwide, no drug has been shown to be sufficiently effective for treating COVID-19. We previously found that nafamostat mesylate, an existing drug used for disseminated intravascular coagulation (DIC), effectively blocked Middle East respiratory syndrome coronavirus (MERS-CoV) S protein-mediated cell fusion by targeting transmembrane serine protease 2 (TMPRSS2), and inhibited MERS-CoV infection of human lung epithelium-derived Calu-3 cells. Here we established a quantitative fusion assay dependent on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein, angiotensin I converting enzyme 2 (ACE2) and TMPRSS2, and found that nafamostat mesylate potently inhibited the fusion while camostat mesylate was about 10-fold less active. Furthermore, nafamostat mesylate blocked SARS-CoV-2 infection of Calu-3 cells with an effective concentration (EC)50 around 10 nM, which is below its average blood concentration after intravenous administration through continuous infusion. On the other hand, a significantly higher dose (EC50 around 30 μM) was required for VeroE6/TMPRSS2 cells, where the TMPRSS2-independent but cathepsin-dependent endosomal infection pathway likely predominates. Together, our study shows that nafamostat mesylate potently inhibits SARS-CoV-2 S protein-mediated fusion in a cell fusion assay system and also inhibits SARS-CoV-2 infection in vitro in a cell-type-dependent manner. These findings, together with accumulated clinical data regarding nafamostat’s safety, make it a likely candidate drug to treat COVID-19.