• Vaccine Name: Brucella abortus bacA mutant
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000347
• Type: Live, attenuated vaccine
• Antigen: The antigen for this vaccine is a bacA deletion mutant of Brucella abortus, known as KL7 (bacAmut-KL7) (Parent et al., 2007).
• Preparation: The bacA mutant strain designated as bacAmut-KL7 was produced by deleting a portion of the bacA gene from the parent strain, B. abortus 2308. The vaccines were produced, each dose containing 5 × 10^4 bacterial colony forming units per dose (Parent et al., 2007).

Mouse Response

• Host Strain: BALB/c, C57BL/6 and C57BL/6 IFNγ−/− mice
• Vaccination Protocol: Eight to 12-week-old mice were infected intra-peritoneally with 5 × 10^4 bacterial colony forming units of B. abortus 2308, bacAmut-KL7 or hfq3 (Parent et al., 2007).
• Persistence: IFNγ-activated macrophages equivalently controlled strains 2308 and bacAmut-KL7. The bacAmut-KL7 organism and its LPS induced greater amounts of pro-inflammatory cytokines than 2308 (Parent et al., 2007).
• Immune Response: The C57BL/6 mice mounted a strong TH1 immune response to infection with B. abortus which was characterized by continuous IFNγ production. At 4 weeks post-infection, a time corresponding to the plateau phase of infection, there was no significant difference in the number of 2308 and bacAmut-KL7 CFU recovered from C57BL/6 mice. BacAmut-KL7 was significantly attenuated in BALB/c mice during this time. During the clearance phase of the infection bacAmut-KL7 did show significant attenuation in C57BL/6 mice relative to 2308 although it was much less than that observed in BALB/c mice (Parent et al., 2007).
• Side Effects: The bactAmut-KL7 mutant was more pathogenic in C57BL/6 interferon-γ-deficient mice than 2308 causing abscesses and wasting even though the splenic loads of bacAmut-KL7 were significantly lower (Parent et al., 2007).
• Challenge Protocol: No challenge was conducted, but it is known that the mutant created, bacAmut-KL7, has protected against challenge in previous experiments (Parent et al., 2007).