Which is not true of exotoxins?

B. The genetic material that encodes most of them is plasmid or prophage associated.

Many are encoded in the chromosome.

It is mostly by exclusion since some of these are qualitative.

A. They rarely have enzymatic activity.

Clostridium perfringens α-toxin is a lecithinase.

C. They can be converted to toxoids.

Tetanus toxoid is produced by treating the toxin with iodoform.

D. The exotoxin can work by binding and entering the host cell.

Part B of the cholera toxin molecule binds to the surface of the intestinal epithelial cells inserting part A which ezymatically (another example) activates a G-protein in an irreversible manner.

E. They can cause toxemia.

Localized infection by Corynebacterium diphtheriae can result in disseminated disease by virtue of circulating toxin

D