Abstract: Shigella vaccine strains whose primary attenuating feature is deletion of the virG(icsA) gene and additional two or more deletions in setAB(shET1), senA(shET2), senB(shET2-2), stxAB, and msbB2 genes. Thus, the vaccine strain will have three or more deletions in the identified genes, will be safer, and will reduce or eliminate symptoms of fever and diarrhea in humans. The following specific vaccine strains have been constructed: WRSS3 (?senA, ?senB, ?virG, ?msbB2), WRSf2G15 (?virG, ?setAB, ?senA, ?senB, ?msbB2), and WRSd5 (?virG, ?stxAB, ?senA, ?senB, ?msbB2).

Abstract: Shigella vaccine strains whose primary attenuating feature is deletion of the virG(icsA) gene and additional two or more deletions in setAB(shET1), senA(shET2), senB(shET2-2), stxAB, and msbB2 genes. Thus, the vaccine strain will have three or more deletions in the identified genes, will be safer, and will reduce or eliminate symptoms of fever and diarrhea in humans. The following specific vaccine strains have been constructed: WRSS3 (?senA, ?senB, ?virG, ?msbB2), WRSf2G15 (?virG, ?setAB, ?senA, ?senB, ?msbB2), and WRSd5 (?virG, ?stxAB, ?senA, ?senB, ?msbB2).

Abstract: With the goal of creating a combination vaccine against Shigella and other diarrheal pathogens we have constructed a prototype vaccine strain of Shigella flexneri 2a (SC608) that can serve as a vector for the expression and delivery of heterologous antigens to the mucosal immune system. SC608 is an asd derivative of SC602, a well-characterized vaccine strain, which has recently undergone several phase 1 and 2 trials for safety and immunogenicity. Using non-antibiotic asd-based plasmids, we have created novel constructs for the expression of antigens from enterotoxigenic E. coli (ETEC), including CFA/I (CfaB and CfaE) and the B-subunit from heat-labile enterotoxin (LTB) in Shigella vaccine strain SC608. Heterologous protein expression levels and cellular localization are critical to immune recognition and have been verified by immunoblot analysis.