What is an example of a superantigen?

What is an example of a superantigen?

Examples of superantigens include toxic shock syndrome toxin-1 (TSST-1), Streptococcal pyrogenic exotoxins (SPE), Staphylococcal enterotoxins (SE), and enterotoxogenic E. coli (ETEC) enterotoxin.

What is meant by superantigen?

Superantigens are a class of immunostimulatory molecules produced by bacteria and viruses. Their potent immune effects are due to their unique ability to bind to the major histocompatibility complex (MHC) outside the antigen-binding cleft and to stimulate T cells in a T-cell receptor (TCR) Vbeta-specific manner.

What is the difference between antigen and superantigen?

Antigens are foreign substances (mostly proteins, polysaccharide) or altered self proteins that induces specific immune response. Superantigens are microbial peptides that can polyclonally activate large portion of T cells.

Is TSS a superantigen?

Toxic shock syndrome toxin (TSST) is a superantigen with a size of 22 kDa produced by 5 to 25% of Staphylococcus aureus isolates. It causes toxic shock syndrome (TSS) by stimulating the release of large amounts of interleukin-1, interleukin-2 and tumour necrosis factor.

Is Covid a superantigen?

These data suggest that the SARS-CoV-2 S may act as a superantigen to drive the development of MIS-C as well as cytokine storm in adult COVID-19 patients, with important implications for the development of therapeutic approaches.

What is a superantigen quizlet?

Superantigens are * proteins that bind to and activate all of the T cells in an individual that express a particular set or family of Vb T cell receptors (TCR) genes.

What is superantigen A What does this antigen cause?

Superantigens (SAgs) are a class of antigens that result in excessive activation of the immune system. Specifically it causes non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release.

Which staphylococcal protein is superantigen?

The Superantigen Superfamily. The staphylococcal SAgs include the staphylococcal enterotoxins (SEs), the staphylococcal enterotoxin-like (SEls) proteins, and toxic shock syndrome toxin-1 (TSST-1) (Lina et al., 2004).

Why is TSST-1 a superantigen?

Staphylococcal and streptococcal toxic shock syndrome toxins (TSST-1, streptococcal pyrogenic exotoxins, streptococcal mitogenic exotoxin Z260) are superantigens that can activate large numbers of circulating T cells to release cytokines.

How does a superantigen work?

Superantigens are bacterial proteins that generate a powerful immune response by binding to Major Histocompatibility Complex class II molecules on antigen-presenting cells and T cell receptors on T cells.

Is LPS a superantigen?

Endotoxin (lipopolysaccharide; LPS) and superantigens (exotoxins) have been identified as potent inducers of lethal shock. While endotoxin primarily interacts with CD14 receptors on macrophages, superantigens like the staphylococcal enterotoxin B (SEB) preferentially activate T cells.

What part of the bacterium is called endotoxin and causes fever and shock?

Gram-nega- tive bacteria cause endotoxic shock. Like fever, the shock produced by endotoxins is related to the secretion of a cytokine by macro- phages. Phagocytosis of gram-negative bacteria causes the phago- cytes to secrete tumor necrosis factor (TNF), sometimes called cachectin.

What is the function of a superantigen in T cell activation?

A superantigen is a molecule that is able to elicit T lymphocyte responses by circumventing normal antigen processing and presentation functions. Superantigens are defined by their ability to stimulate a large fraction of T cells via interaction with the TCR Vβ domain (Figure 4.11).

Is TSST-1 a virulence factor?

Virulence factors are the main pathogenesis of S. aureus as a pathogen, which induce the host’s innate and adaptive immune responses. Toxic shock syndrome toxin 1 (TSST-1) is one of the most important virulence factors of S.

What does superantigen a cause?

Superantigens cause symptoms via release of immune cytokines. These proteins should be considered potential causes of illnesses such as rheumatic fever, arthritis, Kawasaki syndrome, atopic dermatitis, and guttate psoriasis because of their potent immune system-altering capacity.

What is the difference between bioburden and endotoxin?

Endotoxin is a descriptive term used to define a piece of gram-negative bacteria that is harmful to humans. As mentioned earlier, bioburden refers to a viable cell count. Bioburden quantifies viable microorganisms because microorganisms are of infectious concern while alive.

Why lipopolysaccharide is called endotoxin?

LPS is also called an endotoxin because it is a toxin located inside the bacterial cell. It was originally theorized that endotoxin is released once the bacteria dies.

Where is superantigen located?

Staphylococcal Protein A (SpA), Streptococcal Protein G (SpG) and Peptostreptococcal Protein L (PpL) are B-cell superantigens located on the bacterial cell wall (78, 79).

How does a superantigen harm the body?

Direct effects This excessive uncoordinated release of cytokines, (especially TNF-α), overloads the body and results in rashes, fever, and can lead to multi-organ failure, coma and death. Deletion or anergy of activated T-cells follows infection.