• Vaccine Name: Shigella ribosome-based Vaccine (SRB)
• Target Pathogen: Shigella
• Target Disease: Shigellosis
• Vaccine Ontology ID: VO_0000739
• Type: Live, attenuated vaccine
• Antigen: The protective antigen for this vaccine is O-antigen from S. flexneri 2a (Shim et al., 2007).
• Preparation: Virulent S. flexneri 2a 2457T strains were incubated, then cultured. The cells were then subjected to a high-pressure homogenizer to break down the bacterial ribosome. The ribosome was then purfied. The O-antigen concentration accounted for approximately 5% of the preparation. This vaccine is composed of O-antigen and ribosome isolated from S. flexneri 2a (Shim et al., 2007).
• Virulence: SRV is immunogenic and provides protective efficacy in mice (Shim et al., 2007).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Mice were subcutaneously or intranasally vaccinated on days 0 and 14 with a 2.5 microgram dose of the O-antigen. For a control, attenuated S. flexneri 2a SC602 strain (5 x 10^6 CFU) was administered (Shim et al., 2007).
• Immune Response: Both subcutaneous and intranasal vaccination induced high levels of Ag-specific IgG Ab in sera. Intranasal vaccination elicited robust levels of LPS-specific IgA Ab in the mucosal secretions. The heightened levels were identical to those produced by vaccination with the S. flexneri 2a SC602 strain (Shim et al., 2007).
• Challenge Protocol: One week after the second vaccination, the mice were challenged with virulent S. flexneri 2a (1 x 10^7 or 5 x 10^7 CFU) to induce pulmonary pneumonia (Shim et al., 2007).
• Efficacy: Groups of mice vaccinated intranasally with SRV demonstrated less severe pneumonia than those mice that received subcutaneous vaccines. SRV administration via the parenteral route did not effictively protect against the challenge. Almost 65% of mice that received the intranasal vaccine survived the two vaccine doses compared to about 20% of mice that received the subcutaneous dose. These data suggest that a higher degree of protective immunity is conferred against Shigella by SRV when it is administered by the intranasal route (Shim et al., 2007).