Development of a high performance anion exchange chromatography analysis for mapping of oligosaccharides

In the present study a HPAEC-PAD method is described that was developed for monitoring the consistency of N-glycosylation during the production and purification of recombinant proteins and monoclonal antibodies. The method successfully separated 18 neutral and sialylated oligosaccharides. Results obtained were compared with MALDI-TOF MS and it was shown that both methods gave similar results. in addition, a method validation was performed showing that the HPAEC-PAD analysis was well suited for the mapping and characterization of oligosaccharides. The method was found to be robust and additionally the precision was significantly better compared to the MALDI-TOF MS method. (C) 2009 Elsevier B.V. All rights reserved

Functional Characteristics of a Protective Monoclonal Antibody against Serotype A and C Lipooligosaccharides from Moraxella catarrhalis

A monoclonal antibody (MAb), designated MAb 8E7 (immunoglobulin G3), specific for Moraxella catarrhalis lipooligosaccharide (LOS) was evaluated for its functional activity in vitro and in a mouse model of colonization. Enzyme-linked immunosorbent assay (ELISA) demonstrated that the MAb 8E7 could be prepared to a high titer against LOS of the homologous strain 035E, and that it had bactericidal activity. MAb 8E7 reacted with M. catarrhalis serotype A and C LOSs but not serotype B LOS, as measured by ELISA and Western blotting. On the basis of published structures of LOSs, this suggests that the epitope recognized by MAb 8E7 is directed to a common sequence of either α-GlcNAc-(1→2)-β-Glc-(1→ at the branch substituting position 4 of the trisubstituted Glc residue or a terminal tetrasaccharide α-Gal-(1→4)-β-Gal-(1→4)-α-Glc-(1→2)-β-Glc-(1→ at the branch substituting position 6 of the trisubstituted Glc residue. In a whole-cell ELISA, MAb 8E7 reacted with 70% of the 30 wild-type strains and clinical isolates tested. Immuno-electron microscopy demonstrated that MAb 8E7 reacted with a cell surface-exposed epitope of LOS on strain O35E. MAb 8E7 inhibited the adherence of strain O35E to Chang conjunctival epithelial cells by 90%. Passive immunization with MAb 8E7 could significantly enhance the clearance of strain O35E from mouse lungs in an aerosol challenge mouse model. This enhanced bacterial clearance was inhibited when MAb 8E7 was absorbed by M. catarrhalis serotype A LOS, indicating that the M. catarrhalis LOS-directed antibody may play a major role in the enhancement of M. catarrhalis clearance from lungs. These data suggest that MAb 8E7, which recognizes surface-exposed LOS of M. catarrhalis, is a protective antibody against M. catarrhalis

Identification of a novel sugar 5,7-diacetamido-8-amino- 3,5,7,8,9-pentadeoxy-D-glycero-D-galacto-non-2-ulosonic acid present in the lipooligosaccharide of Vibrio parahaemolyticus O3:K6

A novel sugar, 5,7-diacetamido-8-amino- 3,5,7,8,9-pentadeoxy-D-glycero-D-galacto-non-2-ulosonic acid (NonlA), has been identified as a component of the oligosaccharide (OS) isolated from the lipooligosaccharide (LOS) of the emerging strain of Vibrio parahaemolyticus O3:K6 associated with a global pandemic. In the present study we report the identification and characterization of this novel sugar present in the OS of V. parahaemolyticus O3:K6, using chemical analysis, NMR spectroscopy and mass spectrometry

Genomic and Metabolic Profiling of Nonulosonic Acids in Vibrionaceae Reveal Biochemical Phenotypes of Allelic Divergence in Vibrio vulnificus ▿

Nonulosonic acids (NulOs) encompass a large group of structurally diverse nine-carbon backbone α-keto sugars widely distributed among the three domains of life. Mammals express a specialized version of NulOs called sialic acids, which are displayed in prominent terminal positions of cell surface and secreted glycoconjugates. Within bacteria, the ability to synthesize NulOs has been demonstrated in a number of human pathogens and is phylogenetically widespread. Here we examine the distribution, diversity, evolution, and function of NulO biosynthesis pathways in members of the family Vibrionaceae. Among 27 species of Vibrionaceae examined at the genomic level, 12 species contained nab gene clusters. We document examples of duplication, divergence, horizontal transfer, and recombination of nab gene clusters in different Vibrionaceae lineages. Biochemical analyses, including mass spectrometry, confirmed that many species do, in fact, produce di-N-acetylated NulOs. A library of clinical and environmental isolates of Vibrio vulnificus served as a model for further investigation of nab allele genotypes and levels of NulO expression. The data show that lineage I isolates produce about 20-fold higher levels of NulOs than lineage II isolates. Moreover, nab gene alleles found in a subset of V. vulnificus clinical isolates express 40-fold higher levels of NulOs than nab alleles associated with environmental isolates. Taken together, the data implicate the family Vibrionaceae as a “hot spot” of NulO evolution and suggest that these molecules may have diverse roles in environmental persistence and/or animal virulence