Bordetella pertussis fimbria (FIM)

Bordetella pertussis fimbria refers to the filamentous protein structures (fimbriae or pili) that protrude from the surface of B. pertussis, the causative agent of whooping cough (pertussis)[2][6][7]. They are primarily composed of pilin subunits (main types: Fim2 and Fim3) encoded by the fim2 and fim3 genes, with some contribution from minor subunits (e.g., FimD, which acts as a tip adhesin)[4][7]. Fimbriae mediate strong adherence to ciliated epithelial cells in the respiratory tract, which is essential for colonization, biofilm formation, and immune modulation[2][4][7]. There are distinct serotype-specific fimbriae, most notably types 2 and 3, differing in antigenicity and encoded protein sequences[2][4][8]. Variants (FIM2 and FIM3) are critical virulence factors and important protective antigens included in many acellular pertussis vaccines—the vaccine-induced antibodies inhibit fimbrial adhesion and block infection[2][7][8]. Structurally, the fimbriae are long, flexible rods, ~5.7–7.5 nm in diameter, composed of pentameric repeats with a helical arrangement[1][3][6]. Genes required for the biogenesis and surface display of fimbriae include fimB, fimC, fimD, in addition to the structural subunit genes[4][6][7]. Fimbriae play no known intrinsic role in cell signaling or metabolite transport. Their presence and type are used for bacterial serotyping and could be monitored in vaccine response settings[2][8]; there are no widely recognized safety concerns apart from rare hypersensitivity or injection reactions related to the vaccine.

Other names

Type 2 fimbriaType 3 fimbriaSerotype 2 fimbriaSerotype 3 fimbriaB. pertussis fimbriaFIM2FIM3agglutinogenpili

Induction of antibodies that block fimbrial-mediated adhesion to respiratory epithelium, preventing colonization and infection