VALVULAR ENDOCARDITIS OCCURS AS A PART OF A DISSEMINATED COXIELLA-BURNETII INFECTION IN IMMUNOCOMPROMISED BALB CJ (H-2(D)) MICE INFECTED WITH THE 9-MILE ISOLATE OF COXIELLA-BURNETII/

BALB/cJ (H-2(d)) mice were injected intraperitoneally (ip) with cyclop hosphamide 2 days after ip inoculation with Coxiella burnetii Nine Mil e, phase I. Ten days after infection, disseminated microabscesses, gra nulomas, and microthrombi were observed in most organs, including sple en and liver, and in bone marrow. In addition, endocarditis of the atr ioventricular and semilunar valves, characterized by macrophages and n eutrophils, was present. At the same time, C. burnetii antigen was fou nd in most organs and in cardiac valves, aorta, and pulmonary artery, mainly within macrophages, neutrophils, and endothelial cells. C. burn etii-specific IgG antibodies were detected 150 days after infection bu t not in the early phase of infection. Cardiac valves were devoid of C . burnetii antigen and without residual lesions at 150 days. These fin dings offer the possibility for further studies on the pathogenesis of C. burnetii-associated valvular endocarditis and show that acute stra ins of C. burnetii can cause endocarditis as a part of a disseminated infection in the immunocompromised host.