Background: The coxsackievirus and adenovirus receptor (CAR) and decay-accelerating factor (DAF) are receptors for coxsackievirus B3 (CVB3), a major cause of human viral myocarditis. To test whether soluble virus receptor attenuates CVB3-induced myocarditis and virus replication, we designed a novel virus receptor trap (CAR-DAF:Fc) consisting of both CVB3 receptors and the Fc portion of human IgG1, and evaluated its antiviral effects in experimental viral myocarditis. Methods and Results: Two virus receptor traps, CAR:Fc and CAR-DAF:Fc, were prepared. The virus receptor traps in the supernatant of transfected cells neutralized echovirus, adenovirus, and various serotypes of CVB in a dose-dependent manner. The in vivo efficacy of the traps was evaluated by intramuscular injection of plasmid followed by electroporation, in a murine model of CVB3 myocarditis. Serum levels of the virus receptor traps increased from day 3 and peaked at day 14, at 12.9-fold the baseline value for CAR:Fc and 7.1-fold the baseline value for CAR-DAF:Fc. The three-week survival rate was significantly higher in CAR-DAF:Fc-treated mice (61%) than in CAR:Fc-treated mice (29%) or in controls (15%; p<0.05). Myocardial inflammation, fibrosis, and myocardial virus titers were significantly reduced in the CAR:Fc and CAR-DAF:Fc groups relative to those of the controls. Conclusions: These soluble virus receptor traps attenuated viral infection, attenuated myocardial inflammation and fibrosis, and resulted in higher survival rates in mice with coxsackieviral myocarditis. Therefore, the virus receptor trap may be a novel therapeutic strategy for the treatment of viral myocarditis, although further studies are required to clarify the mechanism.