Abstract: Objective To discuss the myocardial expression of Spry1 and MAPK proteins of viral myocarditis （VMC）, to reveal its mechanism of sudden death, and to provide guides for forensic identification of sudden cardiac death. Methods Thirty Balb/c male mice were randomly divided into VMC group and control group, inoculated intraperitoneally with Coxsackievirus B3 and Eagel’s solution, respectively．After the mice were sacrificed, the cardiac tissues of the mice were taken to proceed regular pathological examination. The changes of Spry1 protein, Spry1 mRNA and MAPK protein were detected by immunohistochemistry, Western blotting and real-time PCR. Results Under light microscope, the pathologic changes included myocardial interstitial edema, inflammatory cells infiltration, myocardial necrosis, and focal and patchy necrosis of myocardial fiber in VMC group. The expression of Spry1 protein in VMC group was lower than that in control group （P<0.05）. There was slightly decreased expression of Spry1 of the mRNA level in VMC group （P>0.05）. But the MAPK protein expression in VMC group was higher than that in control group （P<0.05）. Conclusion The pathway of MAPK/ERK involving Spry1 protein accelerates the expression of collagen, which may contribute to arrhythmia, heart failure and even sudden cardiac death.

Key words: forensic pathology, death, sudden, cardiac, vital myocarditis, Spry protein, MAPK protein