GRL0617 is a potent, selective and competitive noncovalent inhibitor of severe acute respiratory syndrome (SARS-CoV) papain-like protease (PLPro)/deubiquitinase with IC50 of 0.6 μM and Ki of 0.49 μM. GRL0617 inhibits SARS-CoV viral replication in Vero E6 cells with EC50 of 15 microM and has no associated cytotoxicity.