FIG. 1.

LD₅₀s and quantification of lung bacterial loads of B. bronchiseptica strains RB50 and 1289. Groups of three or four C57BL/6 mice were inoculated intranasally with the indicated doses of strains RB50 (A) or 1289 (B). Survival curves were generated by inoculating mice with the indicated dose and determining the percent survival over a 28-day period. (C) Groups of three mice were inoculated intranasally with 1 × 10⁴ CFU of strain RB50 or strain 1289. Bacterial loads in the lungs were quantified 0, 3, 7, 14, and 28 days postinoculation. The dashed line indicates the lower limit of detection. Bacterial numbers are expressed as the log₁₀ means ± standard errors (error bars).