Experimental rabbit models of Chlamydia pneumoniae infection

Chlamydia pneumoniae (TWAR), a common cause of acute respiratory disease in humans, has recently been associated with coronary and aortic atherosclerosis. In this study, we evaluated rabbit models of chlamydial infection to investigate the pathogenesis of C. pneumoniae infection. New Zealand White rabbits were inoculated intranasally and intratracheally with C. pneumoniae, strain AR-39, and primary and repeated infection were assessed. After a single inoculation, lung pathology was characterized by a moderate self-resolving interstitial pneumonia with bronchiolitis of 21 days in duration. Chlamydial DNA was detected by polymerase chain reaction (PCR) intermittently in the upper respiratory tract and lung tissue through day 21 postinoculation, spleen tissue at day 14, and peripheral blood mononuclear cells at days 3 and 21. After repeated inoculations, chlamydial DNA was detected by PCR in the upper respiratory tract and lung tissue through day 42. Lung lesions consisted of multifocal interstitial mononuclear cell aggregates that persisted up to day 42. Watanabe heritable hyperlipidemic rabbits were less susceptible to C. pneumoniae infection. After multiple inoculations of Watanabe rabbits, C. pneumoniae was detected by PCR and/or immunocytochemistry until day 21. In conclusion, C. pneumoniae induced a moderate respiratory infection in these rabbit models.