STRUCTURAL CHARACTERIZATION OF THE LIPOPOLYSACCHARIDE O-ANTIGENS OF BURKHOLDERIA-PSEUDOMALLEI

A serologically typical strain of Burkholderia pseudomallei (strain 30 4b) was found to produce two S-type lipopolysaccharides (LPS) differin g in the chemical structures of their O-polysaccharide (O-PS) componen ts, Structural analysis revealed that one O-antigenic polysaccharide ( O-PS I) is an unbranched high-molecular-weight polymer of 1,3-linked 2 -O-acetyl-6-deoxy-beta-D-manno-heptopyranose residues. The other LPS O antigen (O-PS II) is an unbranched polymer of repeating disaccharide units having the structure ucopyranose-(1-3)-6-deoxy-alpha-L-talopyran ose-(-1 in which ca, 33% of the L-6dTalp residues bear 2-O-methyl and 4-O-acetyl substituents while the other L-6dTalp residues carry only 2 -O-acetyl substituents. Analysis of a serologically atypical strain of B. pseudomallei (strain 824a) produced a single LPS O-PS which was ch emically identical to the 6-deoxy-D-manno-heptan O-PS I. The productio n of two distinct LPS raises the interesting question of their relativ e immunogenicities and consequently their relative importance for diag nostic serology and for the possible development of conjugate vaccines .