• Vaccine Name: Live attenuated B. abortus with deletion of znuA
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000386
• Type: Live, attenuated vaccine
• Antigen: The antigen for this vaccine is live, attenuated B. abortus strain 2308 with a znuA knockout mutation (Yang et al., 2006).
• znuA gene engineering:
  • Type: Gene mutation
  • Description: A suicide plasmid and a B. abortus mutant were constructed, then plasmids from transformants were isolated and analyzed by agarose gel electrophoresis after restriction digestion. B. abortus ΔznuA was electroporated with pBznuA to finalize the mutation (Yang et al., 2006).
  • Detailed Gene Information: Click Here.
• Preparation: ΔznuA mutant, RB51strains were grown overnight in Brucella broth at 37°C. Cells were pelleted, washed twice in sterile phosphate-buffered saline, and diluted to 1 × 10^8 cells/200 μl in sterile PBS. The actual viable inoculum CFU was confirmed by serial dilution tests on Bacto Potato Infusion Agar. Each vaccine consisted of 0.2 ml of this suspension (Yang et al., 2006).
• Virulence: The znuA-deleted mutant is very attenuated (Yang et al., 2006).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Experiments were conducted with 7- to 9-week-old age-matched mice. 0.2 ml of vaccine was administered to mice via intraperitoneal injection (Yang et al., 2006).
• Persistence: Compared to wild-type strain 2308, splenic CFU in B. abortus ΔznuA-dosed mice were significantly decreased at weeks 1, 4, and 8. Importantly, by week 8, in three of the five B. abortus ΔznuA-dosed mice, splenic CFU could not be detected (Yang et al., 2006).
• Challenge Protocol: For challenge study, B. abortus 2308 was diluted in sterile PBS, in which 100 μl of bacterial suspension contained 5 × 10^4 CFU bacteria, and immunized and naive mice were subsequently challenged intraperitoneally. The challenge dose was confirmed by plating B. abortus on PIA (Yang et al., 2006).
• Efficacy: The results showed that the ΔznuA mutant was mostly cleared by 8 weeks postinfection. Splenic CFU detected 4 weeks postchallenge were all wild type, and none were from the ΔznuA mutant. Protection against wild-type B. abortus 2308 challenge was as effective as that obtained with the RB51 or S19 vaccine strain, so this mutant is a potential live vaccine (Yang et al., 2006).