title: Six Novel O Genotypes from Shiga Toxin-Producing Escherichia coli.
abstract: Serotyping is one of the typing techniques used to classify strains within the same species. O-serogroup diversification shows a strong association with the genetic diversity of O-antigen biosynthesis genes. In a previous study, based on the O-antigen biosynthesis gene cluster (O-AGC) sequences of 184 known Escherichia coli O serogroups (from O1 to O187), we developed a comprehensive and practical molecular O serogrouping (O genotyping) platform using a polymerase chain reaction (PCR) method, named E. coli O-genotyping PCR. Although, the validation assay using the PCR system showed that most of the tested strains were successfully classified into one of the O genotypes, it was impossible to classify 6.1% (35/575) of the strains, suggesting the presence of novel O genotypes. In this study, we conducted sequence analysis of O-AGCs from O-genotype untypeable Shiga toxin-producing E. coli (STEC) strains and identified six novel O genotypes; OgN1, OgN8, OgN9, OgN10, OgN12 and OgN31, with unique wzx and/or wzy O-antigen processing gene sequences. Additionally, to identify these novel O-genotypes, we designed specific PCR primers. A screen of O genotypes using O-genotype untypeable strains showed 13 STEC strains were classified into five novel O genotypes. The O genotyping at the molecular level of the O-AGC would aid in the characterization of E. coli isolates and will assist future studies in STEC epidemiology and phylogeny.
authors.affiliation: Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki Miyazaki, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iguchi
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases Tokyo, Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Iyoda
authors.affiliation: Division of Bacteriology, Osaka Prefectural Institute of Public Health Osaka, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Seto
authors.affiliation: Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki Miyazaki, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nishii
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohnishi
authors.affiliation: Organization for Promotion of Tenure Track, University of MiyazakiMiyazaki, Japan; Center for Animal Disease Control, University of MiyazakiMiyazaki, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Mekata
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University Fukuoka, Japan.
authors.forename: Yoshitoshi
authors.initials: Y
authors.lastname: Ogura
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University Fukuoka, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hayashi
keywords: E. coli; O serogroup; PCR; STEC; genotyping techniques