Six of Twelve Neisseria meningitidis lipooligosaccharides (LOS) (L2, L3, L4, L5, L7, and L8) bound specifically with Maackia amurensis leukoagglutinin (MAL), a lectin which recognizes a terminal Neu5Aca2- 3GalB1-4GlcNAc sequence. The binding of these LOSs to the lectin was abolished by a2-3 specific neuraminidase from Newcastle disease virus. Methylation analysis of a representative 35E(L2) LOS before and after neuraminidase treatment confirmed that the sialic acid was 2->3 linked to Gas. Structural studies by other investigators have shown that these six LOS have a terminal lacto-N-neotetraose (LNnT, GalB1-4GlcNAcB1- 3GalB1-4Glc) structure in their oligosaccharides when they are desialylated. Therefore, the sialic acid is a2->3 linked to the terminal Gal of the LNnT sequence when sialylated. These LOS minic human glycolipids, paragloboside (LNnT-ceramide) and sialyl-paragloboside (Neu5Aca2->3paragloboside), in having the same oligosaccharide sequences in their structures. They may paly a role in the virulence of N. meningitidis.We have developed a sensiitive method for the detection and analysis of gram negative bacterial lipopolysaccharides (LPS) including miningococcal LOS on nylon membranes. LPS or LOS are separated by SDS- PAGE and then electrophoretically transferred to nylon membranes. Hydrazide conjugated to digoxigenin ( a plant steroid) reacts with aldehyde groups generated by periodic oxidation of LPS on the membranes. The digoxigenin tagged LPS are then visualized with an alkaline phosphatase labelled antibody to digoxigenin by forming insoluble indigo- like dye. LPS banding patterns in both rough and smooth type LPS in over 20 different bacterial species are similar to those of silver stained companion gels without the nonspecific staining of proteins. The detection of LPS from E. coli 055:B5 and E. coli K12 (rough LPS) is sensitive to 10-20 ng.
