Objective   To study the relationship betw een the infection of Chlamydia pneumoniae(Cpn), human cytomegalovirus(HCMV), hepatitis Avirus(HAV)and the etiology of coronary heart disease, and the interactive effect between the infectious factors.

  Methods   The IgG antibody of Cpn、HCMV、HA Vin ser a from 90 CHD patients and 90 controls were detected by the indirect ELISA assay.

  Results   The positive rates of Cpn, HCMV IgG antibody were 55.6% and 71.1% in CHD cases; 30.0% and 45.6% in controls respectively, the difference of positive rate were found to be significant (P < 0.01);The positive rate of anti-HAV IgG was 81.1% and 75.6% in CHD cases and controls, there was no statistical significance between HAV infection and the etiology of CHD.Interaction analyses showed there was interactive effect between Cpn and CMV infection, the synergy index was 5.80.

  Conclusion   The Cpn infection and HCMV infection may be associated with CHD, there was significant interactive effects between Cpn and HCMV infection, and also no significant correlation between HAV infection and CHD.