Alterations in the chemical composition and antigenicity of Escherichia coli O89 lipopolysaccharide and lipid A after 60Co gamma irradiation.

The chemical composition and the antigenicity of Escherichia coli lipopolysaccharide (LPS) and lipid A were investigated after irradiation with 150 kGy 60Co-gamma ray. Compared to the original preparations, the irradiated LPS showed a significant reduction in glucosamine, glucose and galactose and a decrease in the phosphate content. The fatty acid components were reduced to a smaller degree. Irradiation induced a reduction in the antigenicity of the polysaccharide part. The amount of glucosamine and phosphate decreased in the irradiated lipid A. The fatty acid content was significantly reduced. The alteration in the chemical composition was not paralleled by changes in the antigenicity of irradiated lipid A.