• Vaccine Name: H. pylori VacA protein vaccine
• Target Pathogen: Helicobacter pylori
• Target Disease: Ulcers
• Vaccine Ontology ID: VO_0011479
• Type: Subunit vaccine
• Status: Research
• Antigen: H. pylori vacuolating cytotoxin VacA
• vacA gene engineering:
  • Type: Recombinant protein preparation
  • Description: VacA was purified from culture supernatant of H. pylori CCUG17874. Formaldehyde treatment was carried out by incubation of VacA (approximately 100 mg/ml) in a solution of phosphate-buffered saline (PBS) containing 25 mM lysine and 0.01% thimerosal (Sigma Chemicals, St. Louis, Mo.) plus different concentrations of formaldehyde for 48 h at 37°C followed by dialysis against PBS. Control VacA was treated in the same manner but in the absence of formaldehyde. VacA biological activity was assessed in a HeLa cell-vacuolating assay (14). Briefly, 104
    HeLa cells/well were seeded into 96-well flat-bottomed microtiter plates. After 16 h of incubation, the cells were treated for a further 8 h at 37°C with 2 mg of acid-activated VacA (2) in 100 ml of RPMI medium containing 2% fetal calf serum plus 5 mM ammonium chloride (Manetti et al., 1997).
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000127
• Immunization Route: Oral

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Groups of three 5-week-old male BALB/c mice were treated intragastrically with 5 mg of native or formaldehyde (3.2 mM)-treated VacA. The preparations were exposed to low pH in vitro in order to obtain optimal activation (Manetti et al., 1997).
• Challenge Protocol: Mice were challenged with H. pylori
• Efficacy: Treatment of the Helicobacter pylori vacuolating cytotoxin with very low concentrations of formaldehyde resulted in abrogation of toxic activity in both a HeLa cell vacuolation assay and an in vivo assay of gastric epithelial damage. Detoxification had only a minimal effect on the integrity of the oligomeric or monomeric structure. The toxoid retained the ability to bind to target cells and to induce high-titer neutralizing antibodies after immunization of rabbits. Furthermore, oral immunization of mice with the toxoid resulted in protection against infective challenge with mouse-adapted strains of H. pylori (Manetti et al., 1997).