title: Toxicity of the staphylococcal enterotoxin B mutants with histidine-to-tyrosine substitutions.
abstract: In this study we made a series of site-directed mutants of staphylococcal enterotoxin B (SEB), in which histidine residues in the molecule were replaced by tyrosine. The mutant genes were cloned and expressed, and the corresponding proteins were purified. These mutant proteins were tested for binding to human HLA-DR4 and for mitogenetic activity in mouse splenocyte culture. Toxicity of the proteins in vivo was evaluated in the actinomycin D-primed C3H/HeJ mouse model. We found that SEB mutant proteins with fewer than four histidine-to-tyrosine (his-to-tyr) substitutions retained toxic properties similar to wild-type SEB. However, studies showed that his-to-tyr substitution of four consecutive histidine residues eliminated SEB toxicity. Our results clearly show that this genetically modified SEB protein is non-toxic and justifies its further development as a component of a new, safer vaccine to prevent SEB intoxication.
authors.affiliation: Division of Pathology, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910-7500, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Korolev
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Pinelis
authors.forename: Vladimir
authors.initials: V
authors.lastname: Savransky
authors.forename: Jack
authors.initials: J
authors.lastname: Komisar
authors.forename: Peter
authors.initials: P
authors.lastname: Vogel
authors.forename: Konstantin
authors.initials: K
authors.lastname: Fegeding
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity*; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015804:HLA-DR4 Antigen / Q000378:metabolism; D006639:Histidine / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D008934:Mitogens / Q000235:genetics / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D013211:Staphylococcus aureus / Q000235:genetics*; D013601:T-Lymphocytes / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D004768:Enterotoxins; D015804:HLA-DR4 Antigen; D008934:Mitogens; D011994:Recombinant Proteins; C031818:enterotoxin B, staphylococcal; D014443:Tyrosine; D006639:Histidine