Exfoliative Toxins

Two classical, immunologically different ETs of S. aureus are recognized, ETA, which is chromosomally encoded and heat stable, and ETB, which is carried on a p-lactamase plasmid and is heat inactivated.[9] A serolog-ically different heat-labile ET isolated from a horse strain of S. aureus was termed ETC. Recently, ETD, a novel ET integrated on a pathogenicity island, has been pub-lished.[10] Other SEs causing exfoliation in piglets were named SHETA and SHETB and have been purified from culture supernatants of Staphylococcus hyicus (Table 1).

Superantigenicity of ETs has been a subject of debate for many years. X-ray crystallographic structures of ETs suggest that they are members of the trypsinlike serine protease family. Although protease activity has not been demonstrated in vitro, ETA and ETB have intrinsic esterase activity, which is associated with serine proteases. Recently, desmoglein 1 has been identified as putative target protein for ETA.[11] Whereas some earlier studies describe ETs as mitogens (e.g., because of contamination of the toxin preparation with hitherto unknown superantigens), others fail to demonstrate superantigenic activity. A recent study with recombinant ETA and ETB demonstrates that these recombinant toxins do not act as superantigens.[12]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

Get My Free Ebook

Post a comment