• Vaccine Name: CVD 909
• Target Pathogen: Salmonella spp.
• Target Disease: Salmonellosis
• Vaccine Ontology ID: VO_0004138
• Type: Live, attenuated vaccine
• Status: Licensed
• HtrA gene engineering:
  • Type: Recombinant protein preparation
  • Description: CVD 909 was constructed by replacing the native promoter of tviA with the strong constitutive promoter Ptac (Wang et al., 2000).
  • Detailed Gene Information: Click Here.
• Preparation: S. Typhi CVD 909 was constructed to express the Vi-antigen. This involved a deletion in the promoter region of tviA and an insertion of the sacB-neo cassette, introduced into the chromosome of CVD 908-htrA by homologous recombination. The replacement of the sacB-neo cassette allowed the replacement of the promoter region with the Ptac promoter in a second homologous recombination event (Wang et al., 2000).

Human Response

• Vaccination Protocol: 24 volunteers received a single oral dose of CVD 909 of 10^6–10^9 cfu, and 8 adults received 2 doses of 6 × 10^9 cfu per dose with buffer 14 days apart (Tacket and Levine, 2007).
• Immune Response: All volunteers tested developed IgA anti-LPS ASCs. However, only 1 of the volunteers who ingested a single dose and only 1 of the 8 volunteers who ingested 2 doses developed serum IgG anti-Vi .However, IgA anti-Vi ASC responses were detected in a majority of volunteers who received 10^8–10^9 cfu of CVD 909. These Vi-specific ASC responses provided evidence that the Vi antigen was expressed and immunologically processed, even if serum antibody responses were realitvely small (Tacket and Levine, 2007).
• Side Effects: Not noted.

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Three groups of 6-week-old BALB/c mice were immunized once intranasally with 10^10 CFU of either serovar Typhi strain CVD 908-htrA or CVD 909 or PBS (control) (Wang et al., 2000).
• Immune Response: The mean titer of IgG anti-Vi was much higher in the mice that received CVD 909. However, GMTs of O antibody after immunization were quite similar in the two groups (CVD 909 and CDV 908-htrA) (Wang et al., 2000).
• Side Effects: Not noted.
• Challenge Protocol: Mice were challenged with wild-type serovar Typhi strain Ty2 thirty days after primary immunization (Wang et al., 2000).
• Efficacy: A single mucosal dose of CVD 909 conferred significantly greater protection than CVD 908-htrA (Wang et al., 2000).