TABLE 2.
Attenuation of serovar Abortusovis vaccine strains after oral administration to BALB/c mice and effectiveness in protecting against oral challenge with wild-type serovar Abortusovis strain SS44
| Strain (group/no. of mice) | Relevant genotype | Vaccine
|
Wild type
|
||
|---|---|---|---|---|---|
| Dose (CFU) | No. of survivors/total | Dosea (CFU) | No. of survivorsb/total | ||
| SU304 (A/10) | aroA | 1 × 108 | 10/10 | 1 × 109 | 10/10 |
| SSM189 (B/10) | crp cdt cya | 1 × 108 | 10/10 | 1 × 109 | 10/10 |
| SU40 (C/10) | Plasmid cured | 1 × 108 | 10/10 | 1 × 109 | 10/10 |
| SS44 (D/10) | Wild type | 7 × 107 | 0/10 | ||
a
The serovar Abortusovis SS44 50% lethal dose was 1 × 107 CFU by oral administration.
b
All surviving mice were healthy up to 1 month after challenge with wild-type strain SS44.