FIG. 3.
Time course of rat respiratory tract colonization by wt and ΔcyaA B. bronchiseptica. Wistar rats were inoculated intranasally with 50 μl of PBS containing 5 × 105 CFU of either RB50 (wt; open circles) or RB58 (ΔcyaA; solid circles), and the numbers of bacteria present in the trachea were determined at the indicated times postinoculation. Each symbol represents a single animal, bars represent the means, and the dashed line represents the lower level of detection. Nasal colonization (col.) was determined by nasal swab and is presented as the number of B. bronchiseptica-colonized animals over the total number of rats. ∗, P < 0.01.