• Vaccine Name: S. flexneri 2a strain CVD 1203
• Target Pathogen: Shigella
• Target Disease: Shigellosis
• Vaccine Ontology ID: VO_0002920
• Type: Recombinant vector vaccine
• Antigen: The antigen for this vaccine is S. flexneri 2a strain 1203, a strain which contains deletions in chromosomal aroA and invasion plasmid virG (Noriega et al., 1994).
• AroA gene engineering:
  • Type: Recombinant protein preparation
  • Description: Noriega et al. sequentially introduced precise deletion mutations into chromosomal gene aroA and plasmid gene virG in a wild-type S. flexneri 2a strain known to be virulent in volunteers. In order to do this, they constructed aroA and introduced several deletion cassetes (Noriega et al., 1994).
    
  • Detailed Gene Information: Click Here.
• Virulence: Two 10^9-CFU orogastric doses (2 weeks apart) stimulated production of secretory immunoglobulin A antibodies to S.flexneri 2a and protected against conjunctival sac challenge with virulent S. flexneri 2a.

Guinea pig Response

• Host Strain: Hartley
• Vaccination Protocol: 33 guinea pigs were randomly allocated to receive orogastrically 10 CFU of CVD 1203 or control strain E. coli HS. A second immunization was given 15 days later. Tears were collected from 10 guinea pigs (5 immunized with CVD 1203 and 5 immunized with E. coli HS) on days 7, 14, and 21 after the first orogastric dose to measure secretory immunoglobulin A (S-IgA) antibodies against S. flexneri 2a LPS by enzyme-linked immunosorbent assay (Noriega et al., 1994).
  
• Immune Response: Immunization with CVD 1203 clearly stimulated production of S-IgA antibodies to S. flexneri 2a LPS in tears (Noriega et al., 1994).
• Side Effects: Not noted.
• Challenge Protocol: On the 28th day after the first immunization, 16 vaccinated guinea pigs and 17 control guinea pigs were challenged with 5 x 10^7 CFU of the wild-type 2457T strain in 10 ,ul (Noriega et al., 1996).
• Efficacy: Full-blown keratoconjunctivitis developed in 16 of 17 control animals orogastrically vaccinated with the placebo (a 94% attack rate), in contrast to only 3 of 16 guinea pigs immunized with two spaced orogastric doses of CVD 1203 (a 19% attack rate) (Noriega et al., 1994).
• Host IgA response
  • Description: Immunization with CVD 1203 clearly stimulated production of IgA antibodies to S. flexneri 2a LPS in tears. A significant increase was seen 14 days after immunization, which was compared to the static control immunization with E. coli HS (Noriega et al., 1994).
  • Detailed Gene Information: Click Here.