title: Identification and Characterization of a Novel Staphylococcal Emetic Toxin.
abstract: Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus have superantigenic and emetic activities, which cause toxic shock syndrome and staphylococcal food poisoning, respectively. Our previous study demonstrated that the sequence of SET has a low level of similarity to the sequences of other SEs and exhibits atypical bioactivities. Hence, we further explored whether there is an additional SET-related gene in S. aureus strains. One SET-like gene was found in the genome of S. aureus isolates that originated from a case of food poisoning, a human nasal swab, and a case of bovine mastitis. The deduced amino acid sequence of the SET-like gene showed 32% identity with the amino acid sequence of SET. The SET-like gene product was designated SElY. In the food poisoning and nasal swab isolates, mRNA encoding SElY was highly expressed in the early log phase of cultivation, whereas a high level of expression of this mRNA was found in the bovine mastitis isolate at the early stationary phase. To estimate whether SElY has both superantigenic and emetic activities, recombinant SElY was prepared. Cell proliferation and cytokine production were examined to assess the superantigenic activity of SElY. SElY exhibited superantigenic activity in human peripheral blood mononuclear cells but not in mouse splenocytes. In addition, SElY exhibited emetic activity in house musk shrews after intraperitoneal and oral administration. However, the stability of SElY against heating and pepsin and trypsin digestion was different from that of SET and SEA. From these results, we identified SElY to be a novel staphylococcal emetic toxin.
authors.affiliation: Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan.
authors.forename: Hisaya K
authors.initials: HK
authors.lastname: Ono
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima City, Hiroshima, Japan Doctoral Course of the United Graduate School of Veterinary Sciences, Gifu University, Gifu City, Gifu, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato'o
authors.affiliation: Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Narita
authors.affiliation: Doctoral Course of the United Graduate School of Veterinary Sciences, Gifu University, Gifu City, Gifu, Japan Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan.
authors.forename: Ikunori
authors.initials: I
authors.lastname: Naito
authors.affiliation: Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan.
authors.forename: Shouhei
authors.initials: S
authors.lastname: Hirose
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima City, Hiroshima, Japan.
authors.forename: Junzo
authors.initials: J
authors.lastname: Hisatsune
authors.affiliation: Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan.
authors.forename: Krisana
authors.initials: K
authors.lastname: Asano
authors.affiliation: Laboratory of Zoonoses, Kitasato University School of Veterinary Medicine, Towada, Aomori, Japan.
authors.forename: Dong-Liang
authors.initials: DL
authors.lastname: Hu
authors.affiliation: Doctoral Course of the United Graduate School of Veterinary Sciences, Gifu University, Gifu City, Gifu, Japan Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Omoe
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima City, Hiroshima, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Sugai
authors.affiliation: Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan a27k03n0@hirosaki-u.ac.jp.
authors.forename: Akio
authors.initials: A
authors.lastname: Nakane
mesh_terms: D000818:Animals; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D004639:Emetics / Q000494:pharmacology; D004768:Enterotoxins / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity*; D005517:Foodborne Diseases / Q000382:microbiology; D020869:Gene Expression Profiling; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008414:Mastitis, Bovine / Q000382:microbiology; D008969:Molecular Sequence Data; D009297:Nasal Mucosa / Q000382:microbiology; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012788:Shrews; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018089:Superantigens / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D016207:Cytokines; D004639:Emetics; D004768:Enterotoxins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D018089:Superantigens