Structural elucidation of the O-antigen of the Shigella flexneri provisional serotype 88-893: structural and serological similarities with S. flexneri provisional serotype Y394 (1c)

Genomic Portrait of the Evolution and Epidemic Spread of a Recently Emerged Multidrug-Resistant Shigella flexneri Clone in China

“…S. flexneri is divided into at least 19 serotypes (serotypes 1a, 1b, 1c, 1d, 2a, 2b, 3a, 3b, 4a, 4av, 4b, 5a, 5b, X, Xv, Y, Yv, F6, and 7b), based on the combinations of antigenic determinants present on the O antigen of the cell envelope lipopolysaccharide (LPS) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Serotypes 1c, 4av, 7b, 1d, Yv, and Xv were new serotypes reported in recent years (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), among which serotypes 1c and Xv have caused epidemic-level disease (5,7,9). Serotype Xv first appeared in 2000 in Henan province and subsequently replaced serotype 2a to become the predominant serotype in Henan between 2002 and 2006.…”

Serological Identification and Prevalence of a Novel O-Antigen Epitope Linked to 3- and 4- O -Acetylated Rhamnose III of Lipopolysaccharide in Shigella flexneri

“…Based on combinations of O-antigenic determinants (O factors) on the cell surface lipopolysaccharide (LPS), S. flexneri strains are subdivided into various serotypes. Up to now, a total of 19 serotypes (1a, 1b, 1c[7a], 1d, 2a, 2b, 3a, 3b, 4a, 4av, 4b, 5a, 5b, Y, Yv, X, Xv, 6, and 7b) have been reported by different research groups using the commercially available monovalent antisera kit (Denka Seiken, Japan) and monoclonal antibody reagents (MASFs) (Reagensia AB, Sweden) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). All serotypes except for serotype 6 share an O-antigen backbone with a tetrasaccharide repeat (O-polysaccharide) composed of one N-acetylglucosamine (GlcNAc) and three rhamnose residues (Rha I , Rha II , and Rha III ) (1).…”

“…Glucosylation can occur on any of the monosaccharides in the O unit, giving rise to type I-, IC-, II-, IV-, and V-and group 7,8-specific antigenic determinants in serotypes 1 through 5, 7, X, and Xv (1,6). Adding an O-acetyl group to Rha I at position 2 (2-O-acetylation) confers serotypes 1b, 3a, 3b, 4b, and 7b with group factor 6 (6,18,19).…”

“…Adding an O-acetyl group to Rha I at position 2 (2-O-acetylation) confers serotypes 1b, 3a, 3b, 4b, and 7b with group factor 6 (6,18,19). Glucosylation is mediated by three genes (gtrA, gtrB, and gtr [type specific]) that are arranged in a single operon known as the gtr cluster, which is encoded by serotype conversion bacteriophages, with 6 such bacteriophages identified to date (SfI, SfIC, SfII, SfIV, SfV, and SfX) (20)(21)(22)(23)(24)(25).…”

Serotype-Converting Bacteriophage SfII Encodes an Acyltransferase Protein That Mediates 6-O-Acetylation of GlcNAc in Shigella flexneri O-Antigens, Conferring on the Host a Novel O-Antigen Epitope

“…2-O-acetylation occurs on Rha I in serotypes 1b, 3a, 3b, 4b, and 7b, conferring to the host group 6 and (in serotypes 3a and 3b) type III antigenic determinants (O-factors) (7,8). An acetyltransferase protein encoded by the oac gene which is carried on prophage Sf6 mediates the 2-Oacetylation (9,10).…”