Isolation, structural characterization, and immunological evaluation of a high-molecular-weight exopolysaccharide from Staphylococcus aureus

• Published in: Carbohydrate research 2003-04, Vol.338 (9), p.903-922
• Main Authors: Joyce, Joseph G, Abeygunawardana, Chitrananda, Xu, Qiuwei, Cook, James C, Hepler, Robert, Przysiecki, Craig T, Grimm, Karen M, Roper, Keith, Ip, Charlotte C.Yu, Cope, Leslie, Montgomery, Donna, Chang, Mason, Campie, Sherilyn, Brown, Martha, McNeely, Tessie B, Zorman, Julie, Maira-Litrán, Tomas, Pier, Gerald B, Keller, Paul M, Jansen, Kathrin U, Mark, George E
• Format: Article
• Language: English
• Subjects: Animals; Carbohydrate Conformation; Chromatography, Gel; Enzyme-Linked Immunosorbent Assay; Hemagglutination Tests; High-molecular-weight exopolysaccharide; Levulinic Acids - analysis; Levulinic Acids - chemistry; Magnetic Resonance Spectroscopy; Mice; Molecular Weight; Polysaccharide intercellular adhesin; Polysaccharides, Bacterial - chemistry; Polysaccharides, Bacterial - immunology; Polysaccharides, Bacterial - isolation & purification; Staphylococcus aureus; Staphylococcus aureus - chemistry
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(03)00045-4

Colonization of implanted medical devices by coagulase-negative staphylococci such as Staphylococcus epidermidis is mediated by the bacterial polysaccharide intercellular adhesin (PIA), a polymer of β-(1→6)-linked glucosamine substituted with N-acetyl and O-succinyl constituents. The icaADBC locus containing the biosynthetic genes for production of PIA has been identified in both S. epidermidis and S. aureus. Whereas it is clear that PIA is a constituent that contributes to the virulence of S. epidermidis, it is less clear what role PIA plays in infection with S. aureus. Recently, identification of a novel polysaccharide antigen from S. aureus termed poly N-succinyl β-(1→6)-glucosamine (PNSG) has been reported. This polymer was composed of the same glycan backbone as PIA but was reported to contain a high proportion of N-succinylation rather than acetylation. We have isolated a glucosamine-containing exopolysaccharide from the constitutive over-producing MN8m strain of S. aureus in order to prepare polysaccharide–protein conjugate vaccines. In this report we demonstrate that MN8m produced a high-molecular-weight (>300,000 Da) polymer of β-(1→6)-linked glucosamine containing 45–60% N-acetyl, and a small amount of O-succinyl (approx 10% mole ratio to monosaccharide units). By detailed NMR analyses of polysaccharide preparations, we show that the previous identification of N-succinyl was an analytical artifact. The exopolysaccharide we have isolated is active in in vitro hemagglutination assays and is immunogenic in mice when coupled to a protein carrier. We therefore conclude that S. aureus strain MN8m produces a polymer that is chemically and biologically closely related to the PIA produced by S. epidermidis. A β-(1→6)-linked glucosamine-containing exopolysaccharide isolated from Staphylococcus aureus MN8m ( M r>300,000 Da) and shown to be essentially devoid of succinylate and containing 45–60% N-acetyl is active in hemagglutination assays and is immunogenic in mice when coupled to a protein carrier.