title: Subtyping of Shiga toxin 2 variants in human-derived Shiga toxin-producing Escherichia coli strains isolated in Japan.
abstract: Shiga toxin 2 (Stx2) variants have been found to exhibit not only antigenic divergence, but also differences in toxicity for tissue culture cells and animals. To clarify whether all or just a subset of Stx2 variants are important for the virulence of Shiga toxin-producing Escherichia coli, we designed PCR primers to detect and type all reported variants. We classified them into four groups according to the nucleotide sequences of the Stx2 family; for example, group 1 (G1) contains VT2vha and group 2 (G2) contains VT2d-Ount. The 120 strains of Shiga toxin-producing E. coli used in this study were isolated from humans in Japan between 1986 and 1999. Among the four variant groups, the G1 gene only was detected in 23 of the 120 clinical strains (19.2%) and all belonged to the O157 serotype. G1 is considered the most important Stx2 variant group in terms of human pathogenicity. A multiplex PCR that can detect the stx1, stx2, and G1 genes was developed as a means of rapid and easy typing to better understand the roles of the different types of Stx.
authors.affiliation: Department of Infectious Diseases, National Research Institute for Child Health and Development, 3-35-31 Taishido, Setagaya-ku, Tokyo 154-8567Japan. hnakao@nch.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakao
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Murakami
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Maruyama
authors.forename: Tae
authors.initials: T
authors.lastname: Takeda
mesh_terms: D015373:Bacterial Typing Techniques; D001483:Base Sequence; D017931:DNA Primers; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000145:classification / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D007564:Japan; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods*; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D022622:Shiga Toxin 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D022641:Shiga Toxin 2 / Q000737:chemistry / Q000145:classification* / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D021122:Protein Subunits; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; C450841:shiga toxin 2 B subunit