Composition of the Lipopolysaccharide from Different Capsular Serotype Strains of Haemophilus influenzae

Abstract

Lipopolysaccharide (LPS) from all six serotype strains of Haemophilus injhenzae was similar in composition. The oligosaccharide, of each LPS, was composed of glucose, galactose, heptose and 2-keto-3-deoxyoctonic acid. The lipid A was composed of glucosamine, phosphate and the fatty acids 14:O and 3-OH 14:O. Each LPS also contained ethanolamine and ethanolamine phosphate, and the oligosaccharides from two strains additionally contained small amounts of glucosamine. Although the LPS was similar in composition, different serotypes had quantitative differences, especially in the galactose content, which correlated with the antigenic specificity of their homologous antisera and with their mobility on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). A survey by SDS-PAGE showed that LPS from strains of the serotypes a, c and d was characteristically of lower M , than the LPS from most (80%) serotype b strains. I N T R O D U C T I O NHaemophilus inzuenzae is widespread in the human population, where it colonizes the nasopharynx. Although normally commensal, it has the potential to cause systemic infection in children, including meningitis. It is either non-capsular or expresses one of six antigenically and chemically distinct capsular polysaccharides, designated types a-f (Pittman, 193 1). The majority of strains causing systemic infection synthesize the type b capsule, an acidic polysaccharide with the repeating unit of ribosyl-ribitol-phosphate (PRP) (Moxon & Vaughn, 1981; Turk, 1982). Although the type b capsule is known to be a major virulence factor, a potential role for non-capsular surface components such as the lipopolysaccharide (LPS) of this organism has been indicated by the results of recent studies. These have shown an association between virulence and alterations in LPS as a result of transformation (Zwahlen et al., 1983(Zwahlen et al., , 1985 and also an apparent relationship between virulence and the presence of certain antigenic determinants in H. inpuenzae type b LPS as defined by monoclonal antibodies (Kimura & Hansen, 1986).H. influenzae LPS also displays endotoxic properties similar to those of enterobacterial LPS (Flesher & Insel, 1978) and may be involved in the acquisition of serum resistance . Previous studies have shown the LPS to possess a lipid A moiety and an oligosaccharide, but to lack a high-M, sidechain polysaccharide (Flesher & Insel, 1978;Inzana, 1983). Because of the apparent rough nature of this LPS the term lipo-oligosaccharide is currently being employed by a few authors. However, we prefer to retain the original terminology in order to specify a molecule which has the biological and structural characteristics of an LPS.

Extraction and Purification of Haemophilus influenzae Type b Lipooligosac‌charide by Modified Phenol Method

“…The observed inter-and intra-strain heterogeneity of LOS has been attributed to the oligosaccharide extensions stemming from the triheptose core region [9,10]. Lipid A constitutes about 60% of LOS while the remainder of this molecule consists of hydrophilic polysaccharides [11]. It appears that the structure of lipid A in different strains of Hib is relatively conserved as it has been shown that nearly 50% of a large collection of Hib strains shared at least one epitope in lipid A region [12,13].…”

The role of Dam methylation in phase variation of Haemophilus influenzae genes involved in defence against phage infection

“…It was therefore reasonable to check whether there is a difference between the LOS structure of the resistant and sensitive variant derivatives from both wild-type and dam cells. H. influenzae LOS is a complex glycolipid composed of a membrane-anchoring lipidA portion linked by a single 2-keto-3-deoxyoctulosonic acid (Kdo) molecule to a heterogeneous oligosaccharide composed of neutral heptose and hexose sugars (Zamze & Moxon, 1987;Hood et al, 1996a). Detailed analysis of LOS from H. influenzae Rd strain RM118 showed that this strain produces LOS with a globotetraose…”

Genes required for the synthesis of heptose-containing oligosaccharide outer core extensions in Haemophilus influenzae lipopolysaccharide

“…Lipopolysaccharide (LPS) is the major glycolipid on the bacterial cell surface, is essential for H. influenzae and can have a role in both commensal behaviour and the pathogenesis of H. influenzae infections. H. influenzae LPS comprises a membrane-anchoring lipid A portion linked by a single 2-keto-3-deoxyoctulosonic acid (Kdo) molecule to a heterogeneous oligosaccharide (OS) composed mainly of neutral heptose (Hep) and hexose (Hex) sugars (Zamze & Moxon, 1987). Each Hep of a conserved trisaccharide inner core (HepI-HepIII) (Fig.…”