BRANHAMELLA-CATARRHALIS PATHOGENESIS IN SCID AND SCID BEIGE MICE/

SCID and SCID/beige mice were used to study the pathogenesis of B. cat arrhalis administered by intranasal, intraperitoneal or intravenous ro utes. Challenged adult animals did not appear overtly clinically ill. Similar symptoms were observed regardless of the challenge route, and pretreatment of mice with human transferrin did not enhance clinical v irulence. Susceptibility to B. catarrhalis appeared to be age-dependen t as some mice under one week of age died following challenge. Postmor tem findings included circumscribed pale foci on the liver, splenomega ly and mineralization of the myocardium. Presence of lesions did not c orrelate with the assessment of clinical well being, and severity of t he lesions was found to be challenge strain-dependent. Liver lesions a nd splenomegaly were not observed in animals challenged with heat-kill ed bacteria or placebo. SCID/beige mice were more affected than SCID m ice both clinically and pathologically, suggesting that natural killer cell and polymorphonuclear cell functions may be important in resolvi ng B. catarrhalis challenge.