Feline coronavirus drug inhibits the main protease of SARS-CoV-2 and blocks virus replication

Abstract

The main protease, Mpro (or 3CLpro) in SARS-CoV-2 is a viable drug target because of its essential role in the cleavage of the virus polypeptide. Feline infectious peritonitis, a fatal coronavirus infection in cats, was successfully treated previously with a prodrug GC376, a dipeptide-based protease inhibitor. Here, we show the prodrug and its parent GC373, are effective inhibitors of the Mpro from both SARS-CoV and SARS-CoV-2 with IC50 values in the nanomolar range. Crystal structures of SARS-CoV-2 Mpro with these inhibitors have a covalent modification of the nucleophilic Cys145. NMR analysis reveals that inhibition proceeds via reversible formation of a hemithioacetal. GC373 and GC376 are potent inhibitors of SARS-CoV-2 replication in cell culture. They are strong drug candidates for the treatment of human coronavirus infections because they have already been successful in animals. The work here lays the framework for their use in human trials for the treatment of COVID-19.

Development of a fluorescence based, high-throughput SARS-CoV-2 3CLpro reporter assay

“…3E). Our observed inhibition of the virus is consistent with reports of inhibition of SARS-CoV-2 by GC376 in the literature (22,23). All together, these experiments demonstrate feasibility of using our FlipGFP CoV 3CL pro reporter assay to identify protease-targeting inhibitors of SARS-CoV-2.…”

“…3CL pro , also known as the main protease or M pro , is the more conserved viral protease, with only 5 amino acid changes between SARS/SARSlike CoVs and SARS-CoV-2 compared to the 102 differences found in PL pro (18). 3CL pro cleaves at a highly conserved consensus sequence, LQ¯, across the coronavirus family (19), and has been shown to effectively cleave luciferase-based protease biosensors (20,21) and FRET-based assays (13,17,(22)(23)(24)(25)(26)(27)(28). With the aim of generating a protease reporter compatible with SARS-CoV-2 and other present and future coronaviruses to support viral inhibitor screening, we selected the CoV 3CL pro as our protease target.…”

Multiscale Simulations of SARS-CoV-2 3CL Protease Inhibition with Aldehyde Derivatives. Role of Protein and Inhibitor Conformational Dynamics in the Reaction Mechanism

“…8 Thus, according to our simulations, inhibition of SARS-CoV-2 3CL protease with 11a would be significantly more reversible than with N3. In fact, aldehyde derivative inhibitors have been proposed to act via a reversible formation of the hemithioacetal, 11 which is now confirmed by our simulations. It must be noticed that reversibility can be a desired feature of cysteine protease inhibitors, in particular when extended therapy periods are required.…”

“…Up to know, several families of inhibitors have been proposed and tested in vitro against the 3CL protease of SARS-CoV-2, including Michael acceptors, 8 a-ketoamides, 9 aldehyde derivatives 10,11 and ketones. 12 These compounds first bind into the active site of the protease forming a noncovalent complex (EI) and then react with the thiol group of the catalytic cysteine to form a stable covalent acyl-enzyme complex (E-I), see Figure 1a.…”

Potential COVID-19 papain-like protease PLpro inhibitors: repurposing FDA-approved drugs

“…For coronaviruses, host protease TMPRSS2 provide a possible target where protease inhibitors can prevent viral entry (Hoffmann et al, 2020;Simmons et al, 2005;Zhou et al, 2015). On the other hand, two viral proteases, papain-like protease (PL pro ) and chymotrypsin-like protease (3CL pro , aka main protease) are also attractive as druggable targets (Vuong et al, 2020;Ma et al, 2020). Both proteases are highly conserved specific nsps: nsp5 for 3CL pro and nsp3 for PL pro .…”