Hemagglutinin B (HagB)

Hemagglutinin B (HagB) is a major non-fimbrial adhesin and virulence factor expressed by Porphyromonas gingivalis, a Gram-negative anaerobic bacterium recognized as a keystone pathogen in chronic periodontitis (UniProt P56135; Molecular Oral Microbiology, 2017). It is essential for the stable attachment of the bacteria to host tissues, including oral epithelial cells and vascular endothelial cells, which is a prerequisite for colonization and infection (Molecular Oral Microbiology, 2017; Infection and Immunity, 2005). Beyond adhesion, HagB contributes to the formation and structural integrity of multi-species biofilms, facilitating the persistence of P. gingivalis within the oral microbiome (Molecular Oral Microbiology, 2017). The protein is highly immunogenic and has been shown to activate Toll-like receptor 4 (TLR4), thereby inducing the production of pro-inflammatory cytokines that drive alveolar bone loss and tissue destruction (Vaccines, 2024). Due to its critical role in pathogenesis, HagB is a primary target for the development of periodontal vaccines and anti-adhesion therapies (Human Vaccines & Immunotherapeutics, 2014). Experimental approaches include the use of recombinant HagB proteins and monoclonal antibodies to elicit protective mucosal and systemic immune responses (Vaccines, 2024). While no HagB-targeted drugs are currently FDA-approved, research in animal models has demonstrated that neutralizing HagB can significantly reduce bacterial load and prevent disease progression (Vaccines, 2024). Therapeutic challenges include the potential for sequence variation among different P. gingivalis strains and the risk of exacerbating inflammation if vaccines are administered during active disease (NPJ Vaccines, 2016).

Other names

HagBHemagglutinin B proteinPG0155HagB adhesinPorphyromonas gingivalis Hemagglutinin B

Inhibition of bacterial adhesion to host tissues; Neutralization of virulence factors; Induction of protective mucosal and systemic immunity (IgG/IgA)