title: Lipopolysaccharide glycotyping of clarithromycin-resistant and clarithromycin-susceptible Canadian isolates of Helicobacter pylori.
abstract: Lipopolysaccharide (LPS) of Helicobacter pylori exhibits several unique structures, such as Lewis (Le) antigens, α-1,6-glucan, and dd-heptan. To investigate the relationship between LPS structure and resistance to clarithromycin, 41 Canadian isolates of H. pylori were characterized by whole-cell ELISA (enzyme-linked immunosorbent assay), sugar analysis, immunoblotting, and indirect immunofluorescence. The expression of type 2 Lewis X and (or) Lewis Y antigens was detected in 22 of 23 (95.7%) clarithromycin-resistant and in 14 of 18 (77.7%) clarithromycin-susceptible H. pylori strains (P < 0.05), and 8 isolates co-expressed type 1 and type 2 Le antigens (8/41, 19.5%). A significantly higher frequency of α-1,6-glucan (P < 0.01) was detected in clarithromycin-resistant strains than in clarithromycin-susceptible strains (19/23 (82.6%) versus 11/18 (61.1%)). Sugar analysis of selected α-1,6-glucan-positive H. pylori strains confirmed that they frequently contained elevated amounts of dd-heptose. Clarithromycin-resistant isolates were also characterized by low expression levels or absence of CagA (17/23, 73.9%). Indirect immunofluorescence studies carried out on selected H. pylori strains with rabbit immune sera specific for α-1,6-glucan confirmed broad recognition of α-1,6-glucan epitope. The binding was not affected by LPS glycotype of H. pylori isolates examined nor by their CagA status or resistance to clarithromycin. These findings suggest α-1,6-glucan as a potential vaccine target, especially in an era of increasing clarithromycin resistance in H. pylori.
authors.affiliation: a National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Altman
authors.forename: Blair A
authors.initials: BA
authors.lastname: Harrison
authors.forename: Vandana
authors.initials: V
authors.lastname: Chandan
authors.forename: Robert
authors.initials: R
authors.lastname: Slinger
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002170:Canada; D017291:Clarithromycin / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000737:chemistry* / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D008070:Lipopolysaccharides / Q000032:analysis / Q000737:chemistry; D011135:Polysaccharides, Bacterial / Q000737:chemistry*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; C080866:cagA protein, Helicobacter pylori; D017291:Clarithromycin