• Vaccine Name: RASV expressing Y. pestis Psn
• Target Pathogen: Yersinia pestis
• Target Disease: Plague
• Vaccine Ontology ID: VO_0004159
• Type: Recombinant vector vaccine
• Status: Research
• Psn gene engineering:
  • Type: Recombinant vector construction
  • Description:
  • Detailed Gene Information: Click Here.
• Immunization Route: Orally

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Female BALB/c mice, 6-8 weeks of age, were purchased from Harlan. Mice were deprived of food and water for 4 h prior to immunization and resupplied 30 min after. RASVs (recombinant attenuated Salmonella vaccine) were grown in LB broth to an OD600 of 0.9 and concentrated to a final concentration of 5 x 10^10 CFU/ml in phosphate-buffered saline containing 0.01% gelatin (BSG). Mice were orally immunized with 20 μl of RASV suspensions two times with a one week interval between immunizations. Blood samples were collected on days 0, 7, 35, and 49 (Branger et al., 2007).
• Challenge Protocol: A subcutaneous challenge with virulent Y. pestis strain, CO92, (biovar orientalis) was performed 28 days after the second immunization. Each animal received by subcutaneous injection 3,000 CFU or 600 CFU in the first experiment and 1300 or 60 CFU in a second experiment. Mice were observed daily, and mortality was recorded for 14 days after the challenge. The surviving animals were euthanized after 14 days to obtain blood samples for serological analysis (Branger et al., 2007).
• Efficacy: For mice immunized with RASV expressing rPsn, 2/8 (1,300 CFU) and 4/8 (60 CFU) vaccinated animals died versus 6/8 and 5/8 respectively of the RASV controls, with a delay in time to death in the mice immunized with rPsn. The survival rate of mice vaccinated with RASV-rPsn was significantly higher than that of the RASV controls at the two challenge doses (p<0.045). A combined analysis of the results from groups immunized by RASV-Psn showed significant protection 14 days after challenge (p<0.004). In terms of the onset of death, there was a significant difference between the RASV-rPsn group and the RASV control over all the experiments (Branger et al., 2007).