Protection against fatal Pseudomonas aeruginosa sepsis by immunization with smooth and rough lipopolysaccharides

The protective capacity of various native and mutant lipopolysaccharide antigens against fatal Pseudomonas aeruginosa burn wound sepsis was evaluated. Immunization with O-polysaccharide-deficient lipopolysaccharides derived from Escherichia coli J5 or Salmonella typhi Ty 21a afforded substantial protection against only one of five Pseudomonas aeruginosa challenge strains of various serotypes. Immunization with both lipopolysaccharide antigens evoked antibody of the immunoglobulin G class which recognized lipopolysaccharide isolated from the challenge strain against which protection was noted. This was not seen for the remaining four challenge strains. Attempts to demonstrate cross-serotype protection using O-antigen-deficient and core-deficient Pseudomonas aeruginosa lipopolysaccharide antigens was, for the most part, unsuccessful. In contrast, high levels of protection against all six serotypes of challenge strains were seen following immunization with homologous lipopolysaccharide.