Protease inhibitors targeting coronavirus and filovirus entry

Abstract

In order to gain entry into cells, diverse viruses, including Ebola virus, SARS-coronavirus and the emerging MERS-coronavirus, depend on activation of their envelope glycoproteins by host cell proteases. The respective enzymes are thus excellent targets for antiviral intervention. In cell culture, activation of Ebola virus, as well as SARS- and MERS-coronavirus can be accomplished by the endosomal cysteine proteases, cathepsin L (CTSL) and cathepsin B (CTSB). In addition, SARS- and MERS-coronavirus can use serine proteases localized at the cell surface, for their activation. However, it is currently unclear which protease(s) facilitate viral spread in the infected host. We report here that the cysteine protease inhibitor K11777, ((2S)-N-[(1E,3S)-1-(benzenesulfonyl)-5-phenylpent-1-en-3-yl]-2-{[(E)-4-methylpiperazine-1-carbonyl]amino}-3-phenylpropanamide) and closely-related vinylsulfones act as broad-spectrum antivirals by targeting cathepsin-mediated cell entry. K11777 is already in advanced stages of development for a number of parasitic diseases, such as Chagas disease, and has proven to be safe and effective in a range of animal models. K11777 inhibition of SARS-CoV and Ebola virus entry was observed in the sub-nanomolar range. In order to assess, whether cysteine or serine proteases promote viral spread in the host, we compared the antiviral activity of an optimized K11777-derivative with that of camostat, an inhibitor of TMPRSS2 and related serine proteases. Employing a pathogenic animal model of SARS-CoV infection, we demonstrated that viral spread and pathogenesis of SARS-CoV is driven by serine rather than cysteine proteases and can be effectively prevented by camostat. Camostat has been clinically used to treat chronic pancreatitis, and thus represents an exciting potential therapeutic for respiratory coronavirus infections. Our results indicate that camostat, or similar serine protease inhibitors, might be an effective option for treatment of SARS and potentially MERS, while vinyl sulfone-based inhibitors are excellent lead candidates for Ebola virus therapeutics.

Identification of a coumarin-based antihistamine-like small molecule as an anti-filoviral entry inhibitor

“…Nonspecific cathepsin inhibitors (E64D and leupeptin) and specific cathepsin B/L inhibitors (CA-074, FY-DMK, CID23631927, K11777, and a series of compounds based on epoxysuccinate esters or epoxysuccinate propylamide scaffolds) have been developed to block Ebola virus entry (Barrientos and Rollin, 2007; Gnirss et al, 2012; Kaletsky et al, 2007; Nyakatura et al, 2015; Shah et al, 2010; van der Linden et al, 2016; Zhou et al, 2015). However, due to the dispensability of cathepsins B and L in EBOV replication in vivo , the mechanistic importance of these protease inhibitors, and whether they will provide any therapeutic benefit, is quite questionable (Marzi et al, 2012; Rhein and Maury, 2015).…”

Learning from the Past: Possible Urgent Prevention and Treatment Options for Severe Acute Respiratory Infections Caused by 2019‐nCoV

“…[46] No direct relationship to 3CLpro and PLpro was drawn;h owever,t his class of vinylsulfone small molecule was able to inhibit replication of the virus in the nanomolar range. Recently,S immons andc o-workers developed ac lass of potentialc ovalentc ysteine protease inhibitors that specifically target CoV entry.…”

Filovirus proteins for antiviral drug discovery: A structure/function analysis of surface glycoproteins and virus entry

“…The inhibition of catL and catB, involved in EBOV GP 1,2 endosomal processing, could also have a broad-spectrum antiviral effect. Various more or less specific inhibitors have been described: the unselective Cys and Ser protease inhibitor leupeptin, unselective Cys protease inhibitors E-64 and E-64d and its recent derivatives, the mixed catL and B inhibitor FY-dmk, the specific catB inhibitors CA-074, CA-074Me and nafamostat mesilate (which has a dual action also targeting factor VIIa for an anticoagulation action), and catL-specific inhibitors oxobarzate, ZY(t-Bu)-dmk (also known as CID23631927), triazine derivatives 5705213 and 7402683, and K11777 (Chandran et al, 2005;Schornberg et al, 2006;Barrientos and Rollin, 2007;Shah et al, 2010;Gnirss et al, 2012;Elshabrawy et al, 2014;Nishimura and Yamaya, 2015;Zhou et al, 2015;van der Linden et al, 2016). All these compounds have been characterized in ebolavirus entry modelling systems, such as pseudotypes, and/or studies with infectious virus.…”

“…Attachment Mannose-specific lectins griffithsin, concanavalin A, cyanovirin N (Balzarini et al, 2004;Barton et al, 2014) Endosomal processing Protease inhibitors Cys&Ser protease inhibitors (leupeptin) (Chandran et al, 2005;Schornberg et al, 2006;Barrientos et al, 2007;Shah et al, 2010;Gnirss et al, 2012;Elshabrawy et al, 2014;Nishimura et al, 2015;Zhou et al, 2015;van der Linden et al, 2016) Cys protease inhibitors (E-64 and E-64d) catL&catB inhibitors (FY-dmk) catB inhibitors (CA-074, CA-074Me, nafamostat mesilate) catL inhibitors (oxobarzate, ZY(t-Bu)-dmk, triazine derivatives 5705213 and 7402683, and K11777) Endosome disruption genistein, tyrphostin AG1478, chloroquine (Savarino et al, 2001;Keyaerts et al, 2004;Keyaerts et al, 2009;Madrid et al, 2013) Fusion Intercaling agents LJ001, dUY11, arbidol (St Vincent et al, 2010;Wolf et al, 2010;P echeur et al, 2016) Unclear 25HC oxysterols, teicoplanin (Liu et al, 2013;Schoggins et al, 2013;…”