title: Clostridium difficile PSI polysaccharide: synthesis of pentasaccharide repeating block, conjugation to exotoxin B subunit, and detection of natural anti-PSI IgG antibodies in horse serum.
abstract: Clostridium difficile is the most common cause of antimicrobial-associated diarrhea in humans and may cause death. Previously, we discovered that C. difficile expresses three polysaccharides, named PSI, PSII, and PSIII. It has now been established that PSII is a conserved antigen abundantly present on the cell-surface and biofilm of C. difficile. In contrast, the expression of PSI and PSIII appears to be stochastic processes. In this work, the total chemical synthesis of the PSI pentasaccharide repeating unit carrying a linker at the reducing end, α-l-Rhap-(1→3)-β-d-Glcp-(1→4)-[α-l-Rhap-(1→3)]-α-d-Glcp-(1→2)-α-d-Glcp-(1→O(CH2)5NH2, was achieved by a linear synthesis strategy from four monosaccharide building blocks. The synthesized PSI pentasaccharide was conjugated to a subunit of C. difficile exotoxin B yielding a potential dual C. difficile vaccine. More significantly, sera from healthy horses were shown to contain natural anti-PSI IgG antibodies that detected both the synthetic non-phosphorylated PSI repeat and the native PSI polysaccharide, with a slightly higher recognition of the native PSI polysaccharide.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, ON, Canada.
authors.forename: Yuening
authors.initials: Y
authors.lastname: Jiao
authors.forename: Zuchao
authors.initials: Z
authors.lastname: Ma
authors.forename: Doug
authors.initials: D
authors.lastname: Hodgins
authors.forename: Brittany
authors.initials: B
authors.lastname: Pequegnat
authors.forename: Lisa
authors.initials: L
authors.lastname: Bertolo
authors.forename: Luis
authors.initials: L
authors.lastname: Arroyo
authors.forename: Mario A
authors.initials: MA
authors.lastname: Monteiro
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D060326:Chemistry Techniques, Synthetic; D016360:Clostridioides difficile / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006031:Glycosylation; D006736:Horses / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D011135:Polysaccharides, Bacterial / Q000138:chemical synthesis* / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
chemical_list: D007074:Immunoglobulin G; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D003546:Cysteine Endopeptidases; C042477:streptopain
keywords: Anti-PSI IgG antibodies; C. difficile PSI polysaccharide; C. difficile Toxin B conjugate; Clostridium difficile; Vaccine