Iguchi Atsushi, Iyoda Sunao, Seto Kazuko, Nishii Hironobu, Ohnishi Makoto, Mekata Hirohisa, Ogura Yoshitoshi, Hayashi Tetsuya
Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki Miyazaki, Japan.
Department of Bacteriology I, National Institute of Infectious Diseases Tokyo, Japan.
Front Microbiol. 2016 May 20;7:765. doi: 10.3389/fmicb.2016.00765. eCollection 2016.
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.
血清分型是用于对同一物种内菌株进行分类的分型技术之一。O血清群多样化与O抗原生物合成基因的遗传多样性密切相关。在之前的一项研究中,基于184种已知大肠杆菌O血清群(从O1到O187)的O抗原生物合成基因簇(O-AGC)序列,我们使用聚合酶链反应(PCR)方法开发了一个全面且实用的分子O血清群分型(O基因分型)平台,命名为大肠杆菌O基因分型PCR。尽管使用该PCR系统的验证试验表明,大多数测试菌株成功分类到一种O基因型中,但仍有6.1%(35/575)的菌株无法分类,这表明存在新的O基因型。在本研究中,我们对无法进行O基因型分型的产志贺毒素大肠杆菌(STEC)菌株的O-AGC进行了序列分析,鉴定出六种新的O基因型:OgN1、OgN8、OgN9、OgN10、OgN12和OgN31,它们具有独特的wzx和/或wzy O抗原加工基因序列。此外,为了鉴定这些新的O基因型,我们设计了特异性PCR引物。使用无法进行O基因型分型的菌株进行O基因型筛查,结果显示13株STEC菌株被分类到五种新的O基因型中。对O-AGC进行分子水平的O基因分型将有助于大肠杆菌分离株的特征鉴定,并将有助于未来STEC流行病学和系统发育的研究。