Characteristics of murine cytomegalovirus myocarditis in BALB/c mice

AIM: To study characteristics of murine cytomegalovirus(MCMV) myocarditis in BALB/c mice.METHODS: 60 male BALB/c mice at age of 4 weeks were randomly divided into two groups: 36 in experiment group(injection of MCMV,group A) and 24 in control group(injection of 3T3 liquid,group B).At 3,7,14,21,28,35,42,49,56,63 and 70 days after injection,serum antibodies against myocardial β1 receptor were detected and electrocardiogram was recorded.Gene expression of MCMV was tested.Pathological and immunohistochemical examination were also taken.RESULTS: Total incidences of myocarditis were 69.4%.At acute period,the main pathological changes were myocyte swelling,necrosis and inflammatory cell infiltrating in a focal and dispersed fashion.At chronic period,inflammatory cells infiltrated dispersedly.There were strong expression of cytokine IL-1β and TNF-α at acute period in immunohistochemistry.Total incidences of cardiac arrhythmias were about 50.0% in group A.Most of cardiac arrhythmias were sinus arrhythmias,atrial arrhythmias and conduction black at the former 5 weeks,and were ventricular and atrial arrhythmias at the latter 5 weeks in group A.Gene of MCMV was detected at 3-7 days and was undetectable from 14 to 70 days after virus infection in group A.The titers of serum anti-β1 receptor autoantibody were zero at former 5 weeks and were significantly high at latter 5 weeks in group A,while they were zero from 1 to 7 weeks,but mild elevation from 8 to 10 weeks in group B.CONCLUSION: Myocarditis induced by MCMV is mild,all kinds of arrhythmias can occur.Pathological changes of myocardium and arrhythmias may be associated with MCMV infection at early period and with anti-β1 receptor autoantibody at chronic period.