A-B toxin

Definition

A-B toxins are a class of bacterial exotoxins consisting of two components: the A (active) subunit, which disrupts cell function, and the B (binding) subunit, which facilitates entry into host cells. These toxins are key virulence factors in several pathogenic bacteria causing respiratory infections.

5 Must Know Facts For Your Next Test

1. A-B toxins are produced by bacteria such as Corynebacterium diphtheriae and Bordetella pertussis.
2. The B subunit binds to specific receptors on the host cell surface, allowing the A subunit to enter and exert its toxic effects.
3. Diphtheria toxin is an example of an A-B toxin that inhibits protein synthesis, leading to cell death.
4. Pertussis toxin interferes with signal transduction in host cells, contributing to the symptoms of whooping cough.
5. Vaccines like DTaP target these toxins to prevent diseases such as diphtheria and pertussis.

Review Questions

• What roles do the A and B subunits of A-B toxins play in bacterial pathogenicity?
• Name two bacteria that produce A-B toxins implicated in respiratory infections.
• How do vaccines like DTaP help protect against diseases caused by A-B toxin-producing bacteria?

Related terms

Exotoxin: Toxic proteins secreted by bacteria that can cause damage to the host by destroying cells or disrupting normal cellular metabolism.

Virulence Factor: Molecules produced by pathogens that contribute to their ability to cause disease.

DTaP Vaccine: A vaccine designed to protect against diphtheria, tetanus, and pertussis by inducing immunity through toxoid antigens.