{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T10:39:25Z","timestamp":1790419165296,"version":"4.1.0"},"reference-count":25,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2020,6,10]],"date-time":"2020-06-10T00:00:00Z","timestamp":1591747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["16H06575"],"award-info":[{"award-number":["16H06575"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>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 \u03bcM) 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\u2019s safety, make it a likely candidate drug to treat COVID-19.<\/jats:p>","DOI":"10.3390\/v12060629","type":"journal-article","created":{"date-parts":[[2020,6,12]],"date-time":"2020-06-12T05:02:24Z","timestamp":1591938144000},"page":"629","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":251,"title":["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"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3731-1702","authenticated-orcid":false,"given":"Mizuki","family":"Yamamoto","sequence":"first","affiliation":[{"name":"Research Center for Asian Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maki","family":"Kiso","sequence":"additional","affiliation":[{"name":"Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuko","family":"Sakai-Tagawa","sequence":"additional","affiliation":[{"name":"Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kiyoko","family":"Iwatsuki-Horimoto","sequence":"additional","affiliation":[{"name":"Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masaki","family":"Imai","sequence":"additional","affiliation":[{"name":"Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8194-7727","authenticated-orcid":false,"given":"Makoto","family":"Takeda","sequence":"additional","affiliation":[{"name":"Department of Virology 3, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5471-7363","authenticated-orcid":false,"given":"Noriko","family":"Kinoshita","sequence":"additional","affiliation":[{"name":"Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo 162-8655, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Norio","family":"Ohmagari","sequence":"additional","affiliation":[{"name":"Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo 162-8655, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin","family":"Gohda","sequence":"additional","affiliation":[{"name":"Research Center for Asian Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kentaro","family":"Semba","sequence":"additional","affiliation":[{"name":"Department of Life Science and Medical Bio-Science, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zene","family":"Matsuda","sequence":"additional","affiliation":[{"name":"Research Center for Asian Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yasushi","family":"Kawaguchi","sequence":"additional","affiliation":[{"name":"Research Center for Asian Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"},{"name":"Division of Molecular Virology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshihiro","family":"Kawaoka","sequence":"additional","affiliation":[{"name":"Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"},{"name":"Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53711, USA"},{"name":"Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6389-7036","authenticated-orcid":false,"given":"Jun-ichiro","family":"Inoue","sequence":"additional","affiliation":[{"name":"Research Center for Asian Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan"},{"name":"Senior Professor Office, University of Tokyo, Tokyo 113-0033, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1038\/s41586-020-2012-7","article-title":"A pneumonia outbreak associated with a new coronavirus of probable bat origin","volume":"579","author":"Zhou","year":"2020","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.biochi.2017.07.016","article-title":"TMPRSS2: A potential target for treatment of influenza virus 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