Structural analysis and immunogenicity of Pseudomonas aeruginosa immunotype 2 high molecular weight polysaccharide.

Abstract

We analyzed high molecular weight polysaccharide (PS) from the Fisher immunotype 2 (IT-2) strain of Pseudomonas aeruginosa for molecular composition and structure, then determined its immunogenicity in healthy adults. The PS was composed of 2-acetamido-2,6-dideoxygalactose (N-acetyl fucosamine) and glucose in a molar ratio of 2:1. Structural analysis by carbon-13 and proton nuclear magnetic resonance confirmed that the high molecular weight PS was structurally identical to that of the 0-specific side chain of the lipopolysaccharide. PS differed from this material in molecular size. Immunization of 19 adult volunteers with doses of 50-100 ,ug of PS resulted in significant rises (P < 0.04-P < 0.0001) in binding antibody levels and killing antibody titers 2 and 4 wk postimmunization. The only reaction to the vaccine was localized tenderness at the immunization site. Analysis of the immunoglobulin isotype response to the vaccine showed a rise in specific serum IgG and IgA antibodies. Heterologous responses to other P. aeruginosa PS antigens were not seen. The antibody levels attained by vaccination were comparable with those in acute-phase serum samples of patients who survived sepsis with IT-2 P. aeruginosa and were significantly higher (P < 0.03) than specific antibody levels in bacteremic patients who died. These results confirm that PS is a high molecular weight, immunogenic form of the P. aeruginosa IT-2 serotype antigen, eliciting levels of type-specific antibody comparable with those seen among patients surviving an episode of P. aeruginosa sepsis.

Safety and immunogenicity of a Pseudomonas aeruginosa O-polysaccharide toxin A conjugate vaccine in humans.

“…Similarly, the concentration ofanti-LPS found in the serum ofvaccinated individuals (30 and 32 gg/ml at the 25-and 50-gg doses, respectively) was also comparable to levels obtained by survivors ofP. aeruginosa bacteremia (12.8 pg/ml) (31). Ofperhaps greater significance was the finding that both anti-LPS and antitoxic antibody possessed the desired functional attributes.…”

Pseudomonas aeruginosa-induced lung and pleural injury in sheep. Differential protective effect of circulating versus alveolar immunoglobulin G antibody.

“…This vaccine also has been shown to achieve a plasma level of IgG antibody to P. aeruginosa comparable to the levels measured in patients who survived P. aeruginosa sepsis (7,8). Also, immunization with P. aeruginosa 0-specific polysaccharide antigen has improved survival after a homologous bacterial challenge in both burned and granulocytopenic mice and in a model of pneumonia in guinea pigs (9,10).…”

“…This vaccine also has been shown to achieve a plasma level of IgG antibody to P. aeruginosa comparable to the levels measured in patients who survived P. aeruginosa sepsis (7,8). Also, immunization with P. aeruginosa 0-specific polysaccharide antigen has improved survival after a homologous bacterial challenge in both burned and granulocytopenic mice and in a model of pneumonia in guinea pigs (9,10).However, the magnitude of protection provided by active immunization against P. aeruginosa in modulating the bacterial injury to the different barriers of the lung has not specifically been studied. We have previously developed an experimental animal model that quantifies liquid, protein, and cellular movement across the alveolar epithelial, lung endothelial, and visceral pleural barriers of the intact lung in normal and pathological conditions ( 1 1-13).…”

“…In contrast to older vaccines, which contained the whole endotoxin antigen, a Pseudomonas vaccine containing a high molecular weight, immunogenic 0-specific polysaccharide antigen, but lacking the toxic lipid A component, has been shown to be well tolerated and immunogenic in normal human volunteers (6). This vaccine also has been shown to achieve a plasma level of IgG antibody to P. aeruginosa comparable to the levels measured in patients who survived P. aeruginosa sepsis (7,8). Also, immunization with P. aeruginosa 0-specific polysaccharide antigen has improved survival after a homologous bacterial challenge in both burned and granulocytopenic mice and in a model of pneumonia in guinea pigs (9,10).…”

Immune complexes from immunized mice and infected cystic fibrosis patients mediate murine and human T cell killing of hybridomas producing protective, opsonic antibody to Pseudomonas aeruginosa.

“…The MEP used to immunize mice for studies ofcytotoxic T cell activity had a Kd < 0.3 (approximate molecular size < 300 kD) and provoked only nonopsonic antibodies to MEP when given at doses of50 ,g per mouse. High molecular weight polysaccharide from P. aeruginosa was also prepared as described ( 15 ).…”