Chemical characterization and biological properties of lipopolysaccharides isolated from smooth and rough strains of Brucella abortus.

The chemical composition and some of the biological activities of lipopolysaccharides (LPS) extracted from a smooth-intermediate strain (45/0) and a rough strain (45/20) of Brucella abortus have been examined. LPS were found in both the phenolic and aqueous extraction phases of strain 45/0, but only in the aqueous phase of 45/20. The phenolic LPS contained 9- to 16-fold-lower levels of heptose and reduced amounts of dideoxyaldoses compared with aqueous fractions. The major neutral sugars were glucose, galactose, and mannose. beta-Hydroxymyristic-acid, a common marker of enteric LPS, was not detected. Fatty acids present in highest amounts were hydroxylated and nonhydroxylated species with chain lengths of 16, 18, and 20 carbons. Only the phenolic LPS of strain 45/0 exhibited mouse lethality and a curable wasting disease; however, both phenolic and aqueous fractions caused carbohydrate depletion in mice. The toxicity of aqueous LPS could not be potentiated with Pb(OAc)4. These data, coupled with the lack of mitogenic activity for B-lymphocytes, are indicative of the unique structure-function relationships of Brucella LPS.