@article{f4baa29b81824997b48f6ed099b2042e,
title = "A Clinical-Stage Cysteine Protease Inhibitor blocks SARS-CoV-2 Infection of Human and Monkey Cells",
abstract = "Host-cell cysteine proteases play an essential role in the processing of the viral spike protein of SARS coronaviruses. K777, an irreversible, covalent inactivator of cysteine proteases that has recently completed phase 1 clinical trials, reduced SARS-CoV-2 viral infectivity in several host cells: Vero E6 (EC50< 74 nM), HeLa/ACE2 (4 nM), Caco-2 (EC90 = 4.3 μM), and A549/ACE2 (<80 nM). Infectivity of Calu-3 cells depended on the cell line assayed. If Calu-3/2B4 was used, EC50 was 7 nM, but in the ATCC Calu-3 cell line without ACE2 enrichment, EC50 was >10 μM. There was no toxicity to any of the host cell lines at 10-100 μM K777 concentration. Kinetic analysis confirmed that K777 was a potent inhibitor of human cathepsin L, whereas no inhibition of the SARS-CoV-2 cysteine proteases (papain-like and 3CL-like protease) was observed. Treatment of Vero E6 cells with a propargyl derivative of K777 as an activity-based probe identified human cathepsin B and cathepsin L as the intracellular targets of this molecule in both infected and uninfected Vero E6 cells. However, cleavage of the SARS-CoV-2 spike protein was only carried out by cathepsin L. This cleavage was blocked by K777 and occurred in the S1 domain of the SARS-CoV-2 spike protein, a different site from that previously observed for the SARS-CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of cathepsin L-mediated viral spike protein processing.",
author = "Mellott, {Drake M.} and Tseng, {Chien Te} and Aleksandra Drelich and Pavla Fajtov{\'a} and Chenna, {Bala C.} and Kostomiris, {Demetrios H.} and Jason Hsu and Jiyun Zhu and Taylor, {Zane W.} and Kocurek, {Klaudia I.} and Vivian Tat and Ardala Katzfuss and Linfeng Li and Giardini, {Miriam A.} and Danielle Skinner and Ken Hirata and Yoon, {Michael C.} and Sungjun Beck and Carlin, {Aaron F.} and Clark, {Alex E.} and Laura Beretta and Daniel Maneval and Vivian Hook and Felix Frueh and Hurst, {Brett L.} and Hong Wang and Raushel, {Frank M.} and O'Donoghue, {Anthony J.} and {De Siqueira-Neto}, {Jair Lage} and Meek, {Thomas D.} and McKerrow, {James H.}",
note = "Funding Information: Funding for experiments completed at Utah State University was provided by the Respiratory Diseases Branch, National Institute for Allergy and Infectious Diseases, NIH USA (Contract N01-AI-30048). Funding for the lab of T.D.M at Texas A&M was from AgriLife Research Texas A&M University. We thank W. R. Liu (Texas A&M) for assistance with inhibitor analysis. For the lab of C.K.T, NIAID, Grant # R24 AI120942 NPARS-S01 is acknowledged. This research was supported by a Career Award for Medical Scientists from the Burroughs Wellcome Fund to A.F.C. The following reagent was deposited by the Centers for Disease Control and Prevention and obtained through BEI Resources NIAID, NIH: SARS-Related Coronavirus 2, Isolate USA-WA1/2020, NR-52281. Part of the funding for studies performed at UTMB was provided by Selva Therapeutics, Inc., and J.H. McKerrow is an advisor to Selva Therapeutics, Inc. Funding Information: Funding for experiments completed at Utah State University was provided by the Respiratory Diseases Branch, National Institute for Allergy and Infectious Diseases, NIH USA (Contract N01-AI-30048). Funding for the lab of T.D.M at Texas A&M was from AgriLife Research, Texas A&M University. We thank W. R. Liu (Texas A&M) for assistance with inhibitor analysis. For the lab of C.K.T, NIAID, Grant # R24 AI120942 NPARS-S01 is acknowledged. This research was supported by a Career Award for Medical Scientists from the Burroughs Wellcome Fund to A.F.C. The following reagent was deposited by the Centers for Disease Control and Prevention and obtained through BEI Resources, NIAID, NIH: SARS-Related Coronavirus 2, Isolate USA-WA1/2020, NR-52281. Part of the funding for studies performed at UTMB was provided by Selva Therapeutics, Inc., and J.H. McKerrow is an advisor to Selva Therapeutics, Inc. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",
year = "2021",
month = apr,
day = "16",
doi = "10.1021/acschembio.0c00875",
language = "English (US)",
volume = "16",
pages = "642--650",
journal = "ACS Chemical Biology",
issn = "1554-8929",
publisher = "American Chemical Society",
number = "4",
}