Question

Bacterial superantigens

• A. bind to VβCDR2 loop in T cells without being processed into peptides
• B. bind to VβCDR2 loop in T cells after being processed into peptides
• C. are recognized by B cells after being processed into peptides
• D. bind to VβCDR1 and HV4 loops in T cells without being processed into peptides

Hint:

Superantigens bypass normal antigen processing by directly binding to the TCR Vβ domain, leading to uncontrolled T cell activation.

Answer 1

The Correct Option is A, D

Step 1: Understanding bacterial superantigens.
Superantigens are a class of bacterial proteins that can activate T cells without the need for antigen processing. They bind directly to T cell receptors (TCRs) and MHC class II molecules, leading to massive T cell activation.

Step 2: Analyzing the options.
(A) bind to VβCDR2 loop in T cells without being processed into peptides: This is correct. Superantigens bind to the Vβ domain of the TCR without requiring processing into peptides.
(B) bind to VβCDR2 loop in T cells after being processed into peptides: This is incorrect. Superantigens do not require peptide processing; they bind directly to the TCR.
(C) are recognized by B cells after being processed into peptides: This is incorrect. Superantigens primarily affect T cells, not B cells.
(D) bind to VβCDR1 and HV4 loops in T cells without being processed into peptides: This is incorrect. Superantigens typically bind to the VβCDR2 region of TCR, not VβCDR1 and HV4 loops.

Step 3: Conclusion.
The correct answer is (A) bind to VβCDR2 loop in T cells without being processed into peptides, as bacterial superantigens directly interact with the Vβ region of the TCR.