• Vaccine Name: Recombinant Yersinia rV10 vaccine
• Target Pathogen: Yersinia pestis
• Target Disease: Plague
• Vaccine Ontology ID: VO_0000840
• Type: Subunit vaccine
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0001241
  • Description: Immunization with purified recombinant LcrV (rLcrV) is sufficient to generate protective immunity to both bubonic plague and pneumonic plague in mice, guinea pigs, and non-human primates. LcrV injection of animals triggered release of interleukin-10, a cytokine that suppresses innate immune functions. LcrV also prevents the release of proinflammatory cytokines (gamma interferon and tumor necrosis factor ) in murine and human macrophages. Considering the immune modulatory properties of rLcrV, there are concerns regarding the safety of LcrV vaccines in humans. Thus, there is an emphasis upon searching for variants with reduced immune modulatory properties. rV10, a variant lacking amino acids 271 to 300 of LcrV, displayed a significant decrease in its ability to induce interleukin-10 and to suppress tumor necrosis factor or gamma interferon release (DeBord et al., 2006).
• Preparation: Escherichia coli BL21(DE3) carrying prV10 was grown overnight at 37 °C in Luria-Bertani medium (Difco) with 100 µg/ml ampicillin. Bacteria were diluted in fresh medium and grown to an optical density at 600 nm of 0.8 to 1.0. T7 polymerase expression was induced with 1 mM isopropyl-ß-D-thiogalactopyranoside, and bacterial growth was continued for 3 hours at 37°C. Cells were harvested by centrifugation at 10,000 x g for 10 min. Bacterial sediment was suspended in 20 ml of Tris-HCl (pH 7.5)-150 mM NaCl (column buffer) containing 100 µM phenylmethylsulfonyl fluoride, and cells were disrupted by two passages through a French pressure cell at 14,000 lb/in2. The lysate was subjected to ultracentrifugation at 40,000 x g for 30 min, and the soluble fraction was applied to a nickel nitrilotriacetic acid column (1-ml bed volume) preequilibrated with 10 ml of column buffer. The column was washed with 10 ml of the same buffer, followed by a second (10 ml of column buffer with 10% glycerol) and a third (10 ml of column buffer with 10% glycerol and 20 mM imidazole) washing. Bound protein was eluted in 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, and 10% glycerol containing 250 mM imidazole. Purified proteins were subjected to three sequential Triton X-114 (Sigma) phase separations to remove endotoxins. Purified proteins were applied to a G-25 (Amersham) gel filtration column to remove residual Triton X-114 and then retrieved by phosphate-buffered saline elution. Lipopolysaccharide contamination of purified proteins was assayed with Limulus amebocyte lysate (QCL-1000; Cambrex, New Jersey) and determined to be less than 1 ng/100 µg of purified protein. Protein concentrations were determined by the bicinchoninic acid assay (Pierce Technology, Rockford, IL). Proteins were aliquoted at 1 mg/ml and stored at –80 °C for further use. Purified recombinant rV10 vaccine antigens were emulsified with Alhydrogel (DeBord et al., 2006).
• Virulence:
• Description: Immunization with purified recombinant LcrV (rLcrV) is sufficient to generate protective immunity to both bubonic plague and pneumonic plague in mice, guinea pigs, and non-human primates. LcrV injection of animals triggered release of interleukin-10, a cytokine that suppresses innate immune functions. LcrV also prevents the release of proinflammatory cytokines (gamma interferon and tumor necrosis factor ) in murine and human macrophages. Considering the immune modulatory properties of rLcrV, there are concerns regarding the safety of LcrV vaccines in humans. Thus, there is an emphasis upon searching for variants with reduced immune modulatory properties. rV10, a variant lacking amino acids 271 to 300 of LcrV, displayed a significant decrease in its ability to induce interleukin-10 and to suppress tumor necrosis factor or gamma interferon release (DeBord et al., 2006).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Groups of 10 BALB/c mice were immunized with adjuvant alone or with 50 µg of rV10 on day 0, followed by a booster with an equal dose on day 21. Blood from 5 mice in each immunization set was taken on days 0, 14, 28, and 42 after primary immunization to measure the generation of specific antibodies (DeBord et al., 2006).
• Side Effects: No side effects mentioned.
• Challenge Protocol: On day 43, mice were challenged with 100,000 MLD of Y. pestis CO92 via subcutaneous injection (DeBord et al., 2006). An intranasal infection model of Y. pestis CO92 was also developed using groups of 10 BALB/c mice following the aforementioned 2-dose immunization regimen. Mice were infected on day 43 with 2570 MLD of Y. pestis CO92 delivered by the intranasal route. Animals were monitored for 14 days for signs of lethal disease or death and time-to-death was recorded (DeBord et al., 2006).
• Efficacy: Mice were protected against lethal challenge in all cases, whereas mice receiving adjuvant alone succumbed to disease within 4 days after infection with an average time-to-death of 2.5 days (DeBord et al., 2006).
• Description: In contrast to Yersinia pestis LcrV, the recombinant V10 variant does not suppress the release of proinflammatory cytokines by immune cells. Immunization with rV10 generates robust antibody responses that protect mice against bubonic plague and pneumonic plague, suggesting that rV10 may serve as an improved plague vaccine (DeBord et al., 2006).