Is enterotoxin A superantigen?
Structure. Staphylococcal enterotoxins (SEs) are broadly classified as superantigens, which, as described in detail below, have the ability to stimulate large populations of T cells (~20–30%) leading to the production of a cytokine bolus [23,24].
What is a superantigen exotoxin?
As was learned earlier under Bacterial Pathogenicity, superantigens are type I toxins that can trigger a harmful immune response. Exotoxins are toxins, often proteins in nature, secreted from a living bacterium but also released upon bacterial lysis.
What makes staphylococcal enterotoxin A superantigen?
Staphylococcal enterotoxin B (SEB) is a toxin produced by Staphylococcus aureus. The bacteria produce a repertoire of staphylococcal enterotoxins collectively called superantigens (SAgs) because of their inherent property to activate large amounts of T cells (1).
Which Staphylococcus aureus toxin is a superantigen?
Staphylococcal superantigens include staphylococcal enterotoxins, classically the common causes of food poisoning and nonmenstrual TSS, and TSS toxin 1 (TSST-1), the cause of both menstrual and nonmenstrual TSS [8].
What type of toxin is a superantigen?
Superantigens are unusual bacterial toxins that interact with exceedingly large numbers of T4-lymphocytes. They bind to the surface of the target cell but do not enter the cell. Figure 6.2A. 1: Binding of Peptide Epitopes from Exogenous Antigens to MHC-II Molecules.
How does a superantigen activate a helper T cell?
Microbial superantigens are thought to initiate an immediate T cell response by direct binding to the T cell receptor V β region, bypassing the MHC complex and the need for antigen processing and presentation. This could be an initiating step of autoimmunity.
What is superantigen Staphylococcus aureus?
Staphylococcal enterotoxin B (SEB) of Staphylococcus aureus, and related superantigenic toxins produced by myriad microbes, are potent stimulators of the immune system causing a variety of human diseases from transient food poisoning to lethal toxic shock.
Where does staphylococcal enterotoxin B come from?
Staphylococcal enterotoxin B, produced naturally by Staphylococcus aureus in food, is a very common cause of food poisoning. Respiratory symptoms might differentiate a natural outbreak from a biological attack. Significant morbidity occurs after either ingestion or aerosol exposure.