Table 2. Protection against intra-peritoneal challenge with virulent B. abortus 2308 following oral prime-boost immunization of mice with gamma-irradiated B. neotomae and/or gamma-irradiated B. abortus RB51.
| Vaccine (gamma-irradiated) | Bacterial load in log10 CFU (mean ± SD) | Units of protectiona | |
| Log10 CFU in spleen | None (saline) | 4.66±0.77 | - |
| RB51 | 4.03±0.93** | 0.63 | |
| B. neotomae | 2.55±0.21* | 2.11 | |
| B. neotomae/RB51 | 2.97±0.22* | 1.69 | |
| Log10 CFU in liver | None (saline) | 3.61±0.11 | - |
| RB51 | 2.82±0.32* | 0.79 | |
| B. neotomae | 2.53±0.21* | 1.08 | |
| B. neotomae/RB51 | 2.62±0.25* | 0.99 | |
| Log10 CFU in lung | None (saline) | 2.59±1.18 | - |
| RB51 | 2.71±0.53 | - | |
| B. neotomae | 1.85±0.46** | 0.74 | |
| B. neotomae/RB51 | 1.70±0.28** | 0.89 |
a
Units of protection were calculated by subtracting the mean log10 CFU for a vaccinated group from the mean log10 CFU of the corresponding saline control group.
*Significantly different from the corresponding saline group (P<0.05).
**Not significantly different from the corresponding saline group (P>0.05).