Which one of the following statements about the nature of diphtheria toxin is FALSE?
a. Inhibits protein synthesis in target cells
b. Is a slow acting, heat labile, diffusible protein exotoxin
c. Production greatly influenced by iron concentration
d. Toxigenic cells are invariably lysogenic
e. Toxoid is derived from avirulent strains.
Inhibits protein synthesis in target cells.One of the so-called bifunctional A-B toxins is the diphtheria toxin. While section B attaches to a cell receptor and facilitates the translocation of the A chain into the cytoplasm, portion A mediates the enzymatic activity that stops protein production in the target cell.