Polysaccharide of the slime glycolipoprotein of Pseudomonas aeruginosa.

The polysaccharide moiety was isolated by mild acid hydrolysis from the slime glycolipoprotein of Pseudomonas aeruginosa strain BI. After gel filtration, the polysaccharide obtained from the Carbohydrate peak fractions was found to be lipid- and protein-free. Analyses indicated that the polysaccharide contained the carbohydrate components of the parent glycolipoprotein. Molecular size of the polysaccharide was estimated by gel filtration as 70,000 to 100,000. The polysaccharide showed no indications of toxicity in mice at doses far in excess of the lethal dose for the parent glycolipoprotein, nor did the mice develop the leukopenia that characteristically follows intraperitoneal injection of glycolipoprotein. The polysaccharide acted as an inhibitor of indirect hemagglutination of glycolipoprotein-coated erythrocytes in the presence of anti-glycolipoprotein serum; however, it was not antigenic itself in rabbits. Coupled with methylated bovine serum albumin, the polysaccharide continued to lack the leukopenic and toxic properties of the parent glycolipoprotein, but the coupled polysaccharide was capable of stimulating indirect hemagglutinating antibody against both the polysaccharide and the glycolipoprotein coating erythrocytes. Moreover, the antibody to the coupled polysaccharide protected mice against challenge with lethal doses of viable P. aeruginosa with the same effectiveness as anti-glycolipoprotein serum.