Pathogenesis of CAR bacillus in rabbits, guinea pigs, Syrian hamsters, and mice

Cilia-associated respiratory (CAR) bacillus isolated from infected mice (designated, CBM) and propagated in embryonated chicken eggs was inoculated intranasally in rabbits (Oryctolagus cuniculus), guinea pigs (Cavia porcellus), hamsters (Mesocricetus auratus) and mice (Mus musculus). Gross and microscopic lesions, localization of CBM antigen in the respiratory tract, development of antibody, and ability to reisolate the CAR bacillus were studied in animals killed at 2-, 4-, or 8-week intervals postinoculation (PI). In rabbits, although no histopathological changes were observed in the respiratory tract, CBM antigen was detected on the ciliated epithelium of the respiratory tract, and serum CBM antibody was also detected 4 and 8 weeks PI. In guinea pigs, no histopathological changes were noted, CBM antigen was detected in the respiratory tract 2 and 4 weeks PI but not 8 weeks PI, and serum CBM antibody was detected 4 and 8 weeks PI. In hamsters, mononuclear cell proliferation in the submucosa of the bronchus and trachea was observed 8 weeks PI. CBM antigen was detected at first in the nasal cavity 2 weeks PI and in the lower respiratory tract 4 and 8 weeks PI and serum CBM antibody was detected 4 and 8 weeks PI. In mice, histopathological changes, CBM antigen and CBM antibody were observed. CBM was reisolated from the tracheal washouts of hamsters and mice 8 weeks PI but not from those of rabbits and guinea pigs. These results confirm and extend previous reports of experimentally-induced CAR bacillus infection in mice, guinea pigs, and rabbits. To this list of susceptible laboratory animals, we now add hamsters.(ABSTRACT TRUNCATED AT 250 WORDS)