• Vaccine Name: Recombinant B. abortus RB51WboA
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000404
• Type: Live attenuated B. abortus strain
• Preparation: RB51WboA is a recombinant Brucella strain that complements RB51 with a functional wboA gene. Rough Brucella abortus RB51 is a stable, attenuated mutant vaccine generated strain derived from virulent strain 2308. The wboA gene in RB51 is disrupted by an IS711 element. Abrogation of the wboA gene in smooth , virulent B. abortus, B. melitensis , and B. suis results in rough , attenuated mutants which fail to produce O polysaccharide (O antigen) (Vemulapalli et al., 2000).
• Virulence: RB51WboA is not more virulent than RB51 (Vemulapalli et al., 2000b).

Mouse Response

• Vaccination Protocol: Groups of 13 mice each were vaccinated by intraperitoneal (i.p.) inoculation of viable strains RB51 (3 × 10^8 CFU/mouse), RB51SOD (5 × 10^8 CFU/mouse), RB51WboA (2.5 × 10^8 CFU/mouse) and RB51SOD/WboA (2.8 × 10^8 CFU/mouse) (Vemulapalli et al., 2004).
• Persistence: No bacteria were isolated from the strain RB51WboA- and RB51SOD/WboA vaccinated mice at the time of challenge (Vemulapalli et al., 2004).
• Challenge Protocol: Seven weeks after vaccination, five mice from each group were challenged i.p. with 3 × 10^4 CFU/mouse of virulent B. abortus 2308, and the remaining five mice were challenged i.p. with 2.4 × 10^4 CFU/mouse of virulent B. melitensis 16 M. Two weeks after challenge, the mice were euthanized and the number of CFUs in their spleens were determined (Vemulapalli et al., 2004).
• Efficacy: Mice vaccinated with strains RB51 and RB51SOD showed significant protection in comparison to control. Mice vaccinated with strain RB51SOD showed a significantly better protection (mean reduction in CFU/spleen = 2.9 logs) than the mice vaccinated with strain RB51 (mean reduction in CFU/spleen = 1 log) (P = 0.02). No bacteria were isolated from the strain RB51WboA- and RB51SOD/WboA vaccinated mice, indicating that these mice developed a superior immunity that prevented the infection of B. abortus 2308 (Vemulapalli et al., 2004).