Pertussis toxin

Overview

Structure of the pertussis toxin complex.

Pertussis toxin is a protein-based exotoxin produced by the bacterium Bordetella pertussis, which is the causative agent of whooping cough. This toxin is a major virulence factor of the bacterium and plays a crucial role in the pathogenesis of the disease.

Structure

Pertussis toxin is a multi-subunit protein complex composed of five different subunits, designated S1 through S5. The structure of the toxin is organized into an A-B model, where the A component (S1 subunit) is responsible for the enzymatic activity, and the B component (S2-S5 subunits) facilitates binding to host cells.

Mechanism of Action

The primary action of pertussis toxin is the ADP-ribosylation of the _ subunit of G-proteins in host cells. This modification inhibits the normal function of G-proteins, leading to the disruption of intracellular signaling pathways. As a result, the toxin interferes with the immune response and contributes to the characteristic symptoms of whooping cough.

Pathogenesis

Pertussis toxin contributes to the pathogenesis of whooping cough by:

• Inhibiting phagocytosis by immune cells, allowing Bordetella pertussis to evade the host's immune system.
• Disrupting cytokine production, which impairs the immune response.
• Causing lymphocytosis, an increase in lymphocyte count, which is a hallmark of whooping cough.

Clinical Significance

Pertussis toxin is a key target for vaccination strategies. The acellular pertussis vaccine includes inactivated pertussis toxin as one of its components, which helps to induce immunity against the toxin and protect against whooping cough.

Related Pages

• Bordetella pertussis
• Whooping cough
• Acellular pertussis vaccine
• Exotoxin
• G-protein