Pertussis toxin and filamentous haemagglutinin (PT/FHA)

Pertussis toxin (PT) and filamentous haemagglutinin (FHA) are two primary virulence factors produced by the bacterium Bordetella pertussis, the causative agent of whooping cough (Carbonetti, 2010). PT is a complex AB5-type exotoxin that enters host cells and ADP-ribosylates inhibitory G-proteins, leading to unregulated cAMP levels and disruption of cellular signaling and immune responses (Locht et al., 2011). FHA is a large cell-surface protein that functions as a major adhesin, facilitating the attachment of the bacteria to the ciliated respiratory epithelium and phagocytic cells (Melvin et al., 2014). Together, these proteins are the central components of modern acellular pertussis vaccines, such as DTaP and Tdap, where they serve as antigens to elicit a protective immune response (CDC, 2022). Vaccination with these components induces the production of specific antibodies that neutralize the toxin's systemic effects and inhibit bacterial colonization (Edwards & Berbers, 2014). While highly effective at preventing severe disease, the immunity generated against these targets tends to wane over time, necessitating booster doses to maintain protection (Klein, 2014).

Other names

PTX and FHABordetella pertussis antigensPertussis toxoid and filamentous hemagglutininPT and FHA

Induction of active immunity through the production of neutralizing antibodies that block toxin activity and prevent bacterial attachment to respiratory epithelium.