title: Enterotoxin Gene Cluster-Encoded SEI and SElN from Staphylococcus aureus Isolates are Crucial for the Induction of Human Blood Cell Proliferation and Pathogenicity in Rabbits.
abstract: Among the toxin family of bacterial superantigens, the six members of the enterotoxin gene cluster (egc) seem to have unusual characteristics. They are present in the majority ofStaphylococcus aureusstrains, but their role in disease remains uncertain. We assessed secretion levels, immunogenicity, and toxicity of native and recombinant egc proteins. After having developed enzyme-linked immunosorbent assays, we found different quantities of egc proteins secreted by bacterial isolates. Supernatants induced proliferation of human peripheral blood mononuclear cells. However, purified recombinant egc proteins were shown to have differing superantigenicity potentials. Immunization with identical amounts of all members of egc, and the prominent toxic agent SEB, resulted in neutralizing antisera. Two egc proteins, SEI and SElN, were found to play a predominant role within the cluster. Both displayed the highest potential to activate blood cells, and were essential to be neutralized in supernatants. The application of a supernatant of a strain bearing only egc was sufficient for a lethal outcome in a rabbit model. Again, neutralization of SEI and SElN led to the survival of all tested animals. Finally, nanogram amounts of purified rSEI and rSElN led to lethality in vivo, pointing out the importance of both as virulence determinants among egc superantigens.
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. andreas.roetzer@biomed-research.at.
authors: Andreas
authors: A
authors: Roetzer
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. corina.gr@gmx.at.
authors: Corina S
authors: CS
authors: Gruener
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. guenter.haller@biomed-research.at.
authors: Guenter
authors: G
authors: Haller
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. jbeyerly@gmx.at.
authors: John
authors: J
authors: Beyerly
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. nina.model@biomed-research.at.
authors: Nina
authors: N
authors: Model
authors: Biomedizinische ForschungsgmbH, Lazarettgasse 19/2, Vienna A-1090, Austria. martha.eibl@meduniwien.ac.at.
authors: Martha M
authors: MM
authors: Eibl
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004768:Enterotoxins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D018089:Superantigens / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D011994:Recombinant Proteins; D018089:Superantigens
keywords: Staphylococcus; enterotoxin gene cluster; immunogenicity; toxicity