Abstract: Longer chain antigenic O-polysaccharide chains for use as a hapten in conjugate vaccines can be produced in a controlled manner using recombinant Gram-negative bacteria that overexpress native or heterologous genes of the wzz family, for example wzzB. Bacteria expressing a chosen wzz gene have modified O-polysaccharide chain lengths, allowing the bacteria to produce lipopolysaccharides having the longer O-polysaccharides. The LPS produced by the bacteria can be hydrolyzed to form core-O-polysaccharide molecules that can be conjugated to a carrier molecule, for example flagellin, to produce a vaccine. The invention also provides recombinant bacteria producing the longer chain O-polysaccharides, the polysaccharide molecules, themselves, conjugated vaccines comprising the O-polysaccharides, pharmaceutical compositions and kits.

Abstract: Longer chain antigenic O-polysaccharide chains for use as a hapten in conjugate vaccines can be produced in a controlled manner using recombinant Gram-negative bacteria that overexpress native or heterologous genes of the wzz family, for example wzzB. Bacteria expressing a chosen wzz gene have modified O-polysaccharide chain lengths, allowing the bacteria to produce lipopolysaccharides having the longer O-polysaccharides. The LPS produced by the bacteria can be hydrolyzed to form core-O-polysaccharide molecules that can be conjugated to a carrier molecule, for example flagellin, to produce a vaccine. The invention also provides recombinant bacteria producing the longer chain O-polysaccharides, the polysaccharide molecules, themselves, conjugated vaccines comprising the O-polysaccharides, pharmaceutical compositions and kits.

Abstract: The present invention is drawn to multivalent Salmonella enterica serovar conjugate vaccines comprising conjugates of S. Typhimurium, S. Enteritidis, S. Choleraesuis, S. Typhi, S. Paratyphi A and optionally S. Paratyphi B, wherein the conjugates comprise a hapten antigen and a carrier antigen, wherein at least one of the hapten antigens or carrier antigens is characteristic of the Salmonella enterica serovar. The present invention also provides Salmonella enterica serovar reagent strains to produce the multivalent conjugate vaccines and attenuated Salmonella enterica serovars for use as vaccines.