Antigenic conjugates of conserved lipopolysaccharides of gram negative bacteria

This invention relates to antigenic conjugates of the conserved portion of the lipopolysaccharides of certain gram negative bacteria and to vaccines containing such antigenic conjugates. The conjugates elicit antibodies which exhibit cross reactivity against heterologous strains of gram negative bacteria and the vaccines containing such conjugates induce antibodies which are functional and protective against such gram negative bacterial organisms. Antigenic conjugates are provided which comprise a carrier protein covalently bonded to the conserved portion of a lipopolysaccharide of a gram negative bacteria, wherein the conserved portion of the lipopolysaccharide comprises the inner core and lipid A portions of the lipopolysaccharide, the conjugate eliciting a cross reactive immune response against heterologous strains of the gram negative bacteria.