Expression and structural diversity Haemophilus influenzae:: Implication of the lipopolysaccharide of in virulence

Lipopolysaccharide (LPS) is a major virulence determinant of the human bacterial pathogen Haemophilus influenzae. A characteristic feature of H. influenzae LPS is the extensive intra- and inter-strain heterogeneity of glycoform structure which is key to the role of the molecule in both commensal and disease-causing behaviour of the bacterium. Through the combination of genetics and detailed structural analyses, H. influenzae is an exemplar Gram-negative bacterium for which now the most extensive and detailed LPS structural data and functional correlates are available. LPS from H. influenzae consists of a conserved glucose-substituted triheptosyl inner-core moiety L-alpha-D-Hepp-(1 -> 2)-[PEtn -> 6]-L-alpha-D-Hepp-(1, 3)-[beta-D-Glcp-(1 -> 4)]+L-alpha-D-Hepp linked to lipid A via Kdo 4-phosphate. The inner-core unit provides the template for attachment of oligosaccharide- and non-carbo hydrate substituents. Here, the structure, genetics and expression of LPS glycoforms in the outer core are reviewed as well as their implication on virulence. (c) 2007 Elsevier GmbH. All rights reserved.