<prompt> Which of the following is a superantigenCholera toxinDiphtheria toxinTSSTVero-cytoxin  <response>: Superantigens Certain species of infectious microorganisms produce powerful,immunostimulatory and disease-causing toxins called superantigen, so called because of their ability to a polyclonally active large fraction up to 20 of T cell population. Superangens are potent acvators of T-lymphocytes. Superangens smulate very large numbers of T cells, without relaon to their epitope specificity.This leads to an excessive and dysregulated immune response with release of cytokines IL - 1, IL - 2, TNF - α and IF - γ.Conventional antigens bind to MHC class I or II molecules in the grooveof the β dimer T cell receptor. In contrast, superantigen bind directly to the lateral portion of TCR β chain and MHC class II β chain, and stimulate T cells solely on γ β gene segment utilizedindependent of the D, J and γ aα - sequences present γ β restricted T cell mitogens.Superantigens are capable of giving up to 20 of the peripheral T-cell pool,whereas conventional antigens activate 1 in 10, 000. Examples of superantigen Staphylococcal toxic shock syndrome toxin Certain nonhuman retroviral proteins,Staphylococcal enterotoxins Yersinia pseudotuberculosis Staphylococcal exfoliative erythrogenic toxin Mycoplasma arthritis. Streptococcal toxic shock syndrome toxin Mouse mammary tumor virus. 