title: Characterization and distribution of a new enterotoxin-related superantigen produced by Staphylococcus aureus.
abstract: Staphylococcal enterotoxins (SEs) are a family of structurally related pyrogenic exotoxins consisting of the five prototypic SEs (types A to E) and three newly characterized SEs (types G to I) produced by Staphylococcus aureus (S. aureus). They also work as superantigens and cause food poisoning and shock symptoms in humans. In this study, we cloned a new variant gene of the seg and characterized its superantigenic properties and distribution among the clinical isolates of S. aureus. The gene encodes a 233 amino acid protein which is highly homologous to SEG (97.7%). The variant SEG (SEGv) expressed by the cloned gene exerted mitogenic activity on human peripheral blood mononuclear cells at the concentration of 100 pg/ml. T cells bearing Vbeta3, 12, 13.1, 13.2, 14 and 15 were preferentially expanded after stimulation with the recombinant protein. The mRNA of the variant seg gene was detected in the total RNA of the organisms bearing this gene. By PCR, 27 out of 48 clinical isolates of S. aureus (56%) possessed either the seg or variant seg gene. These findings suggest that SEG, or SEGv, is one of the most frequently produced superantigen exotoxins by S. aureus and may participate in the inflammatory process of the host by activating a distinct set of Vbeta families of T cells.
authors.affiliation: Department of Child Ecology, National Children's Medical Research Center, Tokyo, Japan. jabe@nch.go.jp
authors.forename: J
authors.initials: J
authors.lastname: Abe
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: M
authors.initials: M
authors.lastname: Onimaru
authors.forename: T
authors.initials: T
authors.lastname: Kohsaka
authors.forename: T
authors.initials: T
authors.lastname: Takeda
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D005098:Exotoxins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D014644:Genetic Variation; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009080:Mucocutaneous Lymph Node Syndrome / Q000382:microbiology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018089:Superantigens / Q000737:chemistry / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D004768:Enterotoxins; D005098:Exotoxins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; C411253:SEGv enterotoxin; D018089:Superantigens