• Vaccine Name: B. abortus and B. melitensis mutants with unmarked deletion of asp24, virB2, or manBA
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Type: Aerosal Vaccine
• Antigen: The vaccines tested in this study include B. abortus unmarked mutants BAΔasp24, BAΔvirB2, and BAΔmanBA, and B. melitensis unmarked mutants BMΔasp24, BMΔvirB2, and BMΔmanBA (Kahl-McDonagh et al., 2007).
• asp24 gene engineering:
  • Type: Gene mutation
  • Description: This asp24 mutant is from Brucella abortus (Kahl-McDonagh et al., 2007).
  • Detailed Gene Information: Click Here.
• virB2 gene engineering:
  • Type: Gene mutation
  • Description: This virB2 mutant is from Brucella melitensis (Kahl-McDonagh et al., 2007).
  • Detailed Gene Information: Click Here.
• manA gene engineering:
  • Type: Gene mutation
  • Description: This manBA mutant is from Brucella melitensis (Kahl-McDonagh et al., 2007).
  • Detailed Gene Information: Click Here.
• manB gene engineering:
  • Type: Gene mutation
  • Description: This manBA mutant is from Brucella melitensis (Kahl-McDonagh et al., 2007).
  • Detailed Gene Information: Click Here.
• Preparation: Each vaccine consisted of 5 × 10^7 CFU/ml in a chamber nebulizer, which is thousands of organisms per dose. The bacteria were introduced in Farrell's medium: TSA supplemented with 5 mg/liter nalidixic acid, 25,000 IU/liter bacitracin, 100 mg/liter cycloheximide, 5000 IU/liter polymyxin B sulfate, 20 mg/liter vancomycin, 100,000 IU/liter nystatin 10% (vol/vol) horse serum, and 2% (wt./vol.) dextrose (Kahl-McDonagh et al., 2007).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Groups of four or five female 6- to 8-week-old BALB/c mice were vaccinated via i.p. injection of 1 × 10^6 CFU/ml of unmarked deletion mutant or PBS for naïve controls (Kahl-McDonagh et al., 2007).
• Persistence: Mice receiving a dose of 5 × 10^7 CFU/ml had lung colonization with B. abortus strain 2308 that gradually increased over the first 4 weeks postchallenge, then gradually decreased over the following 4 weeks to 90% of the maximum value. Despite this slight decrease, colonization by the organism in the other tissues was consistent with a chronic infection. Colonization of the liver, although barely detectable at 1 week postchallenge, steadily increased over the first 4 weeks postchallenge and then declined negligibly between weeks 4 and 8. The spleens of infected mice displayed a colonization pattern similar to that of the livers, although the total number of CFU recovered was consistently higher. Spleen colonization increased between weeks 4 and 8, consistent with a persistent infection (Kahl-McDonagh et al., 2007).
• Side Effects: Mice receiving a dose of 5 × 10^7 CFU/ml had lung colonization with 2308 that gradually increased over the first 4 weeks postchallenge, then gradually decreased over the following 4 weeks to 90% of the maximum value. Despite this slight decrease, colonization by the organism in the other tissues was consistent with a chronic infection. Colonization of the liver, although barely detectable at 1 week postchallenge, steadily increased over the first 4 weeks postchallenge and then declined negligibly between weeks 4 and 8. The spleens of infected mice displayed a colonization pattern similar to that of the livers, although the total number of CFU recovered was consistently higher. Spleen colonization increased between weeks 4 and 8, consistent with a persistent infection (Kahl-McDonagh et al., 2007).
• Challenge Protocol: BALB/c mice were challenged with an aerosol chamber dose of 5 × 10^9 CFU/ml of the homologous wild-type strain at 20 weeks postvaccination. Four weeks after the virulent challenge (corresponding to 24 weeks postvaccination), the mice were euthanized and the recovery of the challenge orgainsm was measured (Kahl-McDonagh et al., 2007).
• Efficacy: The bacterial burden in the spleen following aerosol challenge was reduced 2.02 U by vaccination with BAΔasp24 and by 0.86 U by vaccination with BAΔvirB2 relative to the burden in naïve mice. The rough BAΔmanBA mutant was unable to elicit significant protective immunity relative to the immunity of naïve mice. At 24 weeks postvaccination, less protection was observed in the lungs of mice vaccinated with BAΔasp24 and BAΔvirB2, although the protection was significantly greater than that observed for naïve controls. The rough mutant, BAΔmanBA, protected mouse lungs to a lesser degree, which was not significant(Kahl-McDonagh et al., 2007) .