Question:
All of the following have superantigen property EXCEPT:
All of the following have superantigen property EXCEPT:
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Think which of these toxins activates T-cells en masse versus one that just ADP-ribosylates a G protein in the gut.
Updated On: Jun 23, 2026
- Vibrio cholerae
- Streptococcal pyrogenic exotoxin
- Staphylococcal enterotoxins
- None of these
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The Correct Option is A
Solution and Explanation
Answer: Vibrio cholerae.
Step 1: Superantigens (SAgs) are toxins that bind MHC class II molecules outside the normal peptide-binding cleft and cross-link them to the T-cell receptor. This triggers polyclonal, non-specific activation of up to 10 percent of the T-cell pool, causing a massive cytokine storm.
Step 2: The classic bacterial superantigens come from Gram-positive cocci. Staphylococcal toxins (TSST-1, enterotoxins, exfoliative toxin) and streptococcal pyrogenic exotoxins are the textbook examples, so options b and c are genuine superantigens.
Step 3: Vibrio cholerae produces cholera toxin, which is an ADP-ribosylating enterotoxin that raises cyclic AMP and drives secretory diarrhoea. It is NOT a superantigen, which makes it the exception.
Ref: Jawetz Medical Microbiology, 27e, p. 135.
Step 1: Superantigens (SAgs) are toxins that bind MHC class II molecules outside the normal peptide-binding cleft and cross-link them to the T-cell receptor. This triggers polyclonal, non-specific activation of up to 10 percent of the T-cell pool, causing a massive cytokine storm.
Step 2: The classic bacterial superantigens come from Gram-positive cocci. Staphylococcal toxins (TSST-1, enterotoxins, exfoliative toxin) and streptococcal pyrogenic exotoxins are the textbook examples, so options b and c are genuine superantigens.
Step 3: Vibrio cholerae produces cholera toxin, which is an ADP-ribosylating enterotoxin that raises cyclic AMP and drives secretory diarrhoea. It is NOT a superantigen, which makes it the exception.
Ref: Jawetz Medical Microbiology, 27e, p. 135.
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