Pertussis toxin (PT)

Pertussis toxin is a multimeric exotoxin and a critical virulence factor produced by *Bordetella pertussis*, the causative agent of whooping cough[1][3][5]. Structurally, it is composed of six subunits in an AB5 arrangement: a single enzymatically active A (S1) subunit and a pentameric B subunit (S2, S3, two S4, S5) that mediates binding to host cell glycoconjugates[1][3][5]. Once internalized by mammalian cells, pertussis toxin catalyzes the ADP-ribosylation of the α-subunit of heterotrimeric Gi proteins, thereby preventing Gi-coupled receptor signaling, resulting in a broad range of downstream effects including disrupted immune response, leukocytosis, and increased cAMP levels[1][3][5]. Due to these actions, PT is a major contributor to the pathology of pertussis and also serves as a key antigen in acellular pertussis vaccines; neutralizing PT can protect against disease. Therapeutically, PT has been targeted by immunoglobulins and monoclonal antibodies, and experimental inhibitors are under investigation. In research, PT is used as a biochemical tool to dissect G protein signaling. PT’s broad action relates to its non-specific binding to most mammalian cell types, though specific cell-surface receptors are not clearly defined[5].

Other names

PTBordetella pertussis toxinPertussigen

Vaccines: Induction of neutralizing antibodies against PT antigen. Immunoglobulin/antibodies: Neutralization of PT activity. Inhibitors: Blockade of PT enzymatic uptake or function (e.g., chaperone, PPIase inhibitors)[4][6]