Serotype 3 fimbrial subunit (Fim3) (Fim3)

Bordetella pertussis fimbriae type 3 (Fim3) is a major structural protein subunit of the filamentous surface appendages (fimbriae) of the bacterium Bordetella pertussis, the primary cause of whooping cough [1, 2]. Fim3 serves as a critical adhesin that mediates the attachment of the pathogen to the ciliated respiratory epithelium of the host, which is an essential step for colonization and infection [1, 3]. It is also a major agglutinogen used for serotyping B. pertussis strains and its expression is regulated by the BvgAS sensory system [2, 10]. Fim3 is a key component of multi-component acellular pertussis (aP) vaccines, such as the 5-component DTaP and Tdap formulations [4, 8]. Vaccination with Fim3 induces the production of specific IgG antibodies (agglutinins) that inhibit bacterial attachment and facilitate immune-mediated clearance [8, 12]. However, the selective pressure from widespread vaccination has been associated with serotype switching and the emergence of Fim3-variant strains, which may contribute to vaccine escape and the resurgence of pertussis in some populations [10, 14].

Other names

Fim3FIM3Serotype 3 fimbrial subunitBP1568Agglutinogen 3Bordetella pertussis fimbriae type 3 antigenType 3 fimbriae

Induction of active immunity through the production of agglutinating antibodies that block bacterial adhesion to host respiratory cells.