This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Which of the following is a superantigen \nSelect and explain. \nA. Cholera toxin, B. Diphtheria toxin, C. TSST, D. Vero-cytoxin', 'role': 'user'}, {'content': "Answer: C \nExplanation: Superantigens\n\n\xa0Certain species of infectious microorganisms produce powerful,\n\nimmunostimulatory 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.\n\n\xa0Superangens are potent acvators of T-lymphocytes.\n\xa0Superangens smulate very large numbers of T cells, without relaon to their epitope specificity'.\n\nThis leads to an excessive and dysregulated immune response with release of cytokines IL - 1, IL - 2, TNF - α and IF - γ.\n\nConventional antigens bind to MHC class I or II molecules in the groove\n\nof 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 utilized\nindependent of the D, J and γ aα - sequences present → γ β restricted T cell mitogens.\n\nSuperantigens are capable of giving up to 20% of the peripheral T-cell pool,\n\nwhereas conventional antigens activate < 1 in 10, 000.\n\n\xa0Examples of superantigen Staphylococcal toxic shock syndrome toxin □ Certain nonhuman retroviral proteins,\n\nStaphylococcal enterotoxins □ Yersinia pseudotuberculosis Staphylococcal exfoliative (erythrogenic) toxin □ Mycoplasma arthritis. Streptococcal toxic shock syndrome toxin □ Mouse mammary tumor virus.", 'role': 'assistant'}]