Acellular pertussis antigens (aP antigens)

Acellular pertussis antigens are a collection of purified proteins derived from the bacterium Bordetella pertussis, serving as the active components in modern acellular pertussis (aP) vaccines [CDC, 2022]. These antigens typically include pertussis toxoid (an inactivated form of the pertussis toxin), filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3 [WHO, 2015]. In the pathogen, these proteins function as critical virulence factors that facilitate adherence to the respiratory tract and suppress the host immune system [StatPearls, 2023]. As vaccine targets, they stimulate the production of specific IgG antibodies and prime cell-mediated immunity to provide protection against whooping cough [PubMed, 2019]. While acellular vaccines are significantly better tolerated than older whole-cell versions, they are associated with a faster decline in immunity, necessitating periodic booster doses like Tdap in older populations [NIH, 2020]. They are commonly administered in combination with diphtheria and tetanus toxoids in formulations such as DTaP for children and Tdap for adolescents and adults [FDA, 2023].

Other names

Bordetella pertussis antigensPertussis toxoidFilamentous hemagglutininPertactinFimbriae types 2 and 3aP vaccine components

Acellular pertussis antigens act as immunogens that stimulate the host immune system to produce specific IgG antibodies and establish immunological memory. Pertussis toxoid induces neutralizing antibodies against the pertussis toxin, while filamentous hemagglutinin, pertactin, and fimbriae induce antibodies that inhibit bacterial adherence to respiratory epithelial cells, collectively preventing the clinical manifestations of whooping cough [CDC, 2022; WHO, 2015].