Soluble Coxsackievirus B3 3C Protease Inhibitor Prevents Cardiomyopathy in an Experimental Chronic Myocarditis Murine Model

•Re-established the chronic CVB3 myocarditis animal model for drug administration.•Produced water-soluble 3CPI by chemically modifying the water-insoluble 3CPI.•3CPI inhibited virus replication in various organs, myocardial damage, and reduced mortality.•Soluble 3CPI may be beneficial in the treatment of cardiomyopathy associated with enterovirus infection. Coxsackievirus B3 (CVB3) is a common cause of myocarditis and dilated cardiomyopathy. CVB3 3C protease (3CP) cleaves the viral polyprotein during replication. We tested whether a water soluble 3CP inhibitor (3CPI) had antiviral effects in a chronic myocarditis model. Chronic myocarditis was established using DBA/2 strain mice. Starting on post-infection (p.i) day 3, CVB3-infected mice (n=41) were treated with 3CPI by daily intraperitoneal (i.p.) injection at a concentration of 50μM (1.7mg/kg/day) per day for 3 consecutive days. Additional mice (n=49) were injected with PBS as a control. The 5-week survival rate was significantly higher with 3CPI treatment (82.3% versus 47.9%; P