Abstract: To investigate the effect of the CD28 monoclonal antibody (CD28 mAb) on mortality, viral titers of myocardium and pathologic changes of myocardium in CVB3 myocarditis in mice. MethodsA total of 106 BALB/c male mice were used in the experiments, which were randomly divided into the CD28 mAb group (16 mice), the CVB3 group (40 mice), the IgG group (40 mice) and the control group (10 mice). Mice in the former three groups were intraperitoneally inoculated with 0.15?mL CVB3 (TCID50 10-6/mL) and in the control group with 0.15?mL eagle, and then mice in the IgG and the CD28 mAb groups were inoculated with IgG(0.1mg/kg) and CD28 mAb(0.1mg/kg) at 6 hours and 72 hours post-inoculation(p.i.). The surplus mice in each group were sacrificed on day 7. The heart was taken and pathologic changes of cardiac muscle cells were observed under light microscopy, and expression of CVB3 mRNA of myocardium was determined by the realtime quantitative polymerase chain reaction(RQ-PCR) method. ResultsThe mice mortality rate in the CD28 mAb group was lower than that in the CVB3 group (80% vs 50%, P＜0.05); the pathological score（8.88±2.95 vs 5.25±1.91, P＜0.05) and the CVB3mRNA expression level（3.48±2.89 vs 0.51±1.80, P＜0.05). ConclusionCD28 mAb could decrease the expression of CVB3 mRNA, relieve myocardium inflammation and reduce the mortality rate.

Key words: Viral myocarditis, Coxsaokie virus infection, Mice, Inbred BALB C, CD28 monoclonal antibody