Enterotoxigenic Escherichia coli flagellin (FliC) (FliC)

Enterotoxigenic Escherichia coli (ETEC) flagellin, primarily the FliC protein, is the major structural subunit of the bacterial flagellum, essential for motility and chemotaxis (UniProt: P0AEE8). In ETEC pathogenesis, flagellin enables the bacteria to penetrate the intestinal mucus layer and reach the epithelial surface for colonization (PubMed: 25643275). It serves as a potent Pathogen-Associated Molecular Pattern (PAMP) recognized by Toll-like receptor 5 (TLR5), which induces the secretion of pro-inflammatory cytokines such as IL-8 (PubMed: 11591737). Because of its critical role in infection and its high immunogenicity, flagellin is a primary target for vaccine development, including oral whole-cell vaccines like ETVAX and recombinant subunit vaccines (PubMed: 31235471). Furthermore, its TLR5-agonistic properties allow it to function as an effective adjuvant to boost immune responses against other ETEC antigens (PubMed: 28807975). Targeting flagellin aims to both block bacterial motility and stimulate a robust mucosal immune response to prevent diarrheal disease.

Other names

Flagellar filament structural proteinH-antigenFliC proteinFlagellin

Flagellin acts as an immunogen that induces the production of H-antigen-specific antibodies to inhibit bacterial motility and colonization. It also functions as a TLR5 agonist, activating the MyD88-dependent signaling pathway to stimulate innate immune defenses and enhance the adaptive response to co-administered antigens (PubMed: 11591737, 28807975).