Question
Which of the following statements about the toxin shown is incorrect?
| A. |
Most toxic known to man |
| B. |
Causes myocarditis |
| C. |
It is an exotoxin |
| D. |
No vaccine is available |
|
Correct Answer � D Explanation |
 |
Diphtheria Toxin:
– Produced by *Corynebacterium diphtheriae* (tox gene from β-phage).
– It is a potent exotoxin.
– Mechanism: ADP-ribosylation of elongation factor 2 (EF-2) → inhibits protein synthesis → cell death.
– Affects heart (myocarditis), nerves, and throat (pseudomembrane).
Option-wise Clarification:
A. Most toxic known to man – Partially true; botulinum toxin is more potent per weight, but diphtheria toxin is among the most lethal exotoxins.
B. Causes myocarditis – True; myocarditis is a major, life-threatening complication.
C. It is an exotoxin – True; a protein exotoxin secreted by bacteria.
D. No vaccine is available – Incorrect; toxoid vaccine exists as part of DPT (Diphtheria, Pertussis, Tetanus) immunization, providing effective protection via neutralizing antibodies.