Final answer:
The statement is false because intracellular-targeting toxins, known as A-B exotoxins, do not assemble into a pore to disrupt cell membrane integrity; instead, they have a B component for binding and an A component that interferes with cellular functions once inside the host cell.
Step-by-step explanation:
The statement that an intracellular-targeting toxin is made up of multiple protein monomers that assemble into a pore that disrupts the cell membrane integrity is false. Intracellular-targeting toxins, also known as A-B exotoxins, have a different mechanism of action. The B component of the toxin is responsible for binding to specific cell surface receptors, facilitating the toxin's entry into the host cell via endocytosis. Once inside, the A component separates from the B component and interferes with internal cellular functions.
Membrane-disrupting toxins do act by forming pores or disrupting the phospholipid bilayer, as in the case of hemolysins and leukocidins, but this is a separate category from intracellular-targeting toxins. Examples of bacteria producing such toxins include Streptococcus pyogenes with its streptolysins, Staphylococcus aureus with alpha toxin, and Streptococcus pneumoniae with pneumolysin.