title: Detection and measurement of staphylococcal enterotoxin-like K (SEl-K) secretion by Staphylococcus aureus clinical isolates.
abstract: Staphylococcal enterotoxin-like K (SEl-K) is a potent mitogen that elicits T-cell proliferation and cytokine production at very low concentrations. However, unlike the classical enterotoxins SEB and toxic shock syndrome toxin 1 (TSST-1), the gene for SEl-K is commonly present in more than half of all Staphylococcus aureus clinical isolates and is present in almost all USA300 community-acquired methicillin-resistant S. aureus (CA-MRSA) isolates. Sequencing of the sel-k gene in over 20 clinical isolates and comparative analysis with all 14 published sel-k sequences indicate that there are at least 6 variants of the sel-k gene, including one that is conserved among all examined USA300 strains. Additionally, we have developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) that specifically detects and measures SEl-K protein in culture supernatants and biological fluids. Quantification of in vitro SEl-K secretion by various S. aureus isolates using this novel capture ELISA revealed detectable amounts of SEl-K secretion by all isolates, with the highest secretion levels being exhibited by MRSA strains that coexpress SEB. In vivo secretion was measured in a murine thigh abscess model, where similar levels of SEl-K accumulation were noted regardless of whether the infecting strain exhibited high or low secretion of SEl-K in vitro. We conclude that SEl-K is commonly expressed in the setting of staphylococcal infection, in significant amounts. SEl-K should be further explored as a target for passive immunotherapy against complicated S. aureus infection.
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Aguilar
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Avanish K
authors.initials: AK
authors.lastname: Varshney
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Stanford
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Scharff
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA bettina.fries@einstein.yu.edu.
authors.forename: Bettina C
authors.initials: BC
authors.lastname: Fries
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004195:Disease Models, Animal; D004768:Enterotoxins / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005838:Genotype; D006801:Humans; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D004768:Enterotoxins