TABLE 2.
Virulence of A. pleuropneumoniae parent and isogenic mutant strains following aerosol challenge
| A. pleuropneumoniae challenge strain | No. of animals with lung lesions/total no. | Arithmetic mean ± standard deviation of lung lesion scorea | No. of animals with A. pleuropneumoniae reisolated after challenge from:
|
||||||
|---|---|---|---|---|---|---|---|---|---|
| BALF
|
Tonsilbc | Lymph nodeb | Heartb | Lungb
|
|||||
| Day 7 | Day 21 | Pneumonic | Intact | ||||||
| ΔureC ΔexbB mutant | 0/8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| ΔexbB mutant | 0/8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| ΔureC mutant | 7/8 | 5.66 ± 4.02 | 6 | 5 | 1 | 5 | 2 | 7 | 0 |
| wt | 8/8 | 6.64 ± 2.95 | 4 | 7 | 1 | 4 | 0 | 8 | 4 |
a
The lung lesion score was determined as described by Hannan et al. (19).
b
Tissues were examined at postmortem analysis.
c
In tonsil cultures, the presence of A. pleuropneumoniae was likely to be masked frequently by the heavy load of concomitant bacterial growth.