Henke et al. [3] reported that compared with normal mice infected with Coxsackievirus B3 (CVB3), CD4+ T cell knock-out mice infected with CVB3 demonstrated a lower virus titer in the myocardium, a lower mortality rate in the early stages of myocarditis and a more serious inflammatory outcome at the end stage, indicating that T cells mediate heart tissue injury in vivo. The gene discussed is CD4; the disease is myocarditis.