• Vaccine Name: Rickettsia rickettsii vaccine using M. vaccae expressing R. rickettsii OmpA Protein
• Target Pathogen: Rickettsia spp
• Target Disease: Spotted Fever, Typhus
• Vaccine Ontology ID: VO_0011388
• Type: Recombinant vector vaccine
• Status: Research
• ompA gene engineering:
  • Type: Recombinant vector construction
  • Description:
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000142
• Immunization Route: Subcutaneous injection

Mouse Response

• Host Strain: C3H/HeN mice
• Vaccination Protocol: 6–8-week-old male C3H/HeN mice were were inoculated subcutaneously with 1×10^8 to 5×10^8 of recombinant M. vaccae transformants containing rompA3006–3960. As a negative control mice were immunized with either PBS or inoculated subcutaneously with M. vaccae/pCR7, another negative control. Booster inoculations were performed 1 month later with the same dose and route. Mice immunized with M. vaccae transformants were given two additional doses of 100 μg per mouse of recombinant rickettsial GST fusion protein OmpA755–1301 suspended in incomplete Freund’s adjuvant with a 1 month interval between the immunizations (Crocquet-Valdes et al., 2001).
• Challenge Protocol: One month after the last inoculation, all groups of mice were challenged intravenously with three LD50 of R. conorii and observed daily for 2 weeks for morbidity and mortality (Crocquet-Valdes et al., 2001).
• Efficacy: Immunization with one of the constructs of Mycobacterium vaccae expressing Rickettsia rickettsii OmpA in combination with booster immunization with the homologous recombinant protein protected a significant portion of mice from lethal challenge with the closely related bacterium, R. conorii, in mice (Crocquet-Valdes et al., 2001).
• Host Ifng (Interferon gamma) response
  • Description: Production of IFN-gamma by antigen-exposed T-lymphocytes of DNA vaccine recipients indicated that cellular immunity had been stimulated. IFN-γ levels in supernatant fluid of rickettsial antigen-stimulated splenocytes from an animal that received both DNA and protein vaccinations were 47% or more higher than the controls that were vaccinated with the vector and GST or were sham-immunized with saline. This observed difference was significant and was seen in spleen cells the day before the challenge (Crocquet-Valdes et al., 2001).
  • Detailed Gene Information: Click Here.