| Abstrak/Abstract |
While investigating the virulence trait of Staphylococcus aureus adhering to skin of atopic dermatitis (AD) patients, we identified a novel ORF with structural similarity to superantigen from genome sequence data of an isolate from AD skin. Concurrently, the same ORF was identified in a bovine isolate of S. aureus and designated as SEY. Recombinant SEYbov had superantigen activity in human peripheral blood mononuclear cells and showed emetic activity in a non-primate animal model (H. K. Ono et al., Appl. Environ. Microbiol. Jul 2015, AEM.01873-15; DOI: 10.1128/AEM.01873-15). We herein investigated the prevalence of the sey gene in 270 human clinical isolates of various origins in Japan. Forty-six strains were positive for the sey gene, and the positive isolates were predominant in skin diseases atopic dermatitis and impetigo/SSSS with an average detection rate of ~20%. There were three variants of SEY (SEY1, SEY2, and SEY3), and isolates producing SEY variants formed three distinct clusters corresponding to clonal complexes (CCs) 121, 59, and 20, respectively, suggesting clonal distribution of SEY variants in human isolates of S. aureus. Most sey+ isolates produced SEY in broth culture. Like SEYbov, the three recombinant SEY variants exhibited similar biological activities and stability to heating and digestive enzymes. SEY predominantly activated human T cells with a particular TCR V? profile, a unique observation since most staphylococcal enterotoxins exert their superantigenic activities through activating T cells with specific TCR V? profiles. SEY may act to induce localized inflammation via skin-resident T cell activation, facilitate pathogenesis of S. aureus infection in disrupted epithelial barriers. |
