Fimbrial antigen type 2

Fimbrial antigen type 2 refers to a class of bacterial surface proteins that form filamentous structures known as fimbriae or pili. These structures are found on the surface of various Gram-negative bacteria—including Salmonella, Actinomyces, and Bordetella pertussis—and play a critical role in mediating adhesion to host cells and colonization during infection. In some species like Actinomyces oris, type 2 fimbria consists primarily of shaft proteins such as FimA and tip adhesins like FimB; their assembly requires specific sortase enzymes (e.g., SrtC2). In Salmonella paratyphi B and related organisms, type 1 and type 2 fimbriae share similar antigens but differ functionally—type 1 mediates adhesion while type 2 may represent mutational variants with reduced adhesive properties but preserved immunogenicity. In the context of Bordetella pertussis, "Fimbrial antigen types 2/3" refer specifically to two serologically distinct forms included as components in acellular pertussis vaccines. These antigens stimulate protective immunity by inducing antibody responses that block bacterial attachment and colonization during infection with B. pertussis—the causative agent of whooping cough. The main clinical application is thus prophylactic vaccination against infectious disease rather than direct therapeutic targeting after infection has occurred. Overall, "Fimbrial antigen type 2" is best understood as a structural bacterial protein complex involved in pathogenesis through adhesion mechanisms—and serves both as an important virulence factor for bacteria and an effective target for vaccine-mediated prevention strategies.

Other names

Type 2 fimbrial antigenType 2 fimbriaFim2 (in the context of Bordetella pertussis)Type II fimbriae

Induction of actively acquired immunity by stimulating an immune response against the bacterial pathogen expressing this antigen when used in vaccines