Fimbrial protein of Bordetella pertussis (FIM) (FIM)

Fimbrial antigens, specifically Fim2 and Fim3, are filamentous surface appendages produced by Bordetella pertussis, the bacterium responsible for pertussis or whooping cough (Mooi, 1988). These proteins function as adhesins, enabling the pathogen to bind specifically to the ciliated respiratory epithelial cells of the host, which is a crucial first step in colonization and infection (Geuijen et al., 1997). In the context of immunology, they are known as agglutinogens because antibodies against them cause the bacteria to clump together (Preston et al., 2003). Fim2 and Fim3 are key components of many acellular pertussis vaccines (aP), such as DTaP and Tdap, where they are included to elicit a protective immune response (CDC, 2022). Clinical studies have shown that higher levels of anti-fimbrial antibodies correlate with increased protection against disease (Storsaeter et al., 1998). However, the bacteria can undergo serotype switching between Fim2 and Fim3 expression, which may impact long-term vaccine effectiveness in certain populations (Mooi et al., 2000).

Other names

Fim2Fim3Agglutinogen 2Agglutinogen 3Serotype 2 antigenSerotype 3 antigenPiliFimbriaeFim2/3

Vaccines containing these antigens induce the production of neutralizing antibodies (agglutinins) that bind to the fimbriae, blocking the bacteria's ability to adhere to the respiratory cilia and facilitating clearance by the immune system (Edwards & Berbers, 2014).