RABBIT MODEL FOR CHLAMYDIA-PNEUMONIAE INFECTION

A rabbit model was established for Chlamydia pneumoniae infection that may be helpful to understand the pathogenesis of disease in humans, T welve, pathogen-free, I-month-old New Zealand White rabbits were inocu lated with 1.0 x 10(7) to 5.0 x 10(7) CFU of purified C. pneumoniae (A TCC strain VR 1310) via the nasopharynx (1 rabbit died immediately pos tinoculation, and 11 were available for study), Five controls were ino culated with the carrier buffer, Ten of the II study rabbits demonstra ted serological evidence of acute infection (immunoglobulin G antibodi es, 1:8 to >1:16), with the weakest response at 7 days and the stronge st response at 28 days, whereas none of the controls showed any seroco nversion. Study animals were sacrificed in batches of three, on days 7 , 14, 21, and 28, but controls were sacrificed on days 7 and 28, Two-t hirds of the animals demonstrated evidence of bronchiolitis and pneumo nia on days 7 and 14 and resolution by day 21, Two study rabbits demon strated, on histology, early and intermediate lesions of atheroscleros is: one animal (day 7) showed the accumulation of foamy macrophages (f atty streak) in the arch of the aorta, and the other animal (day 14) s howed spindle cell proliferation of smooth muscle cells (intermediate lesion), Focal periaortitis was seen in the same animal (day 7), C. pn eumoniae elementary bodies were demonstrated by immunocytochemical sta in in the lungs (n = 2), liver (n = 3), spleen (n = 5), and aorta (n = 12), one of which corresponded to the intermediate lesion, C. pneumon iae was cultured from the lungs (n = 2), liver (n = 2), spleen (n = 2) , and aortic arch (n = 1), All histopathological, immunocytochemical, and cultural studies were negative in the controls, Hence, the rabbit provides a useful animal model for the study of C. pneumoniae infectio n and its complications, particularly atherosclerosis.