Nontypeable Haemophilus influenzae adhesin protein E (Protein E (PE))

Nontypeable Haemophilus influenzae adhesin protein E (PE) is a small, highly conserved, 16 kDa outer membrane lipoprotein expressed by nearly all clinical isolates of nontypeable Haemophilus influenzae (NTHi)[2][7][4]. It functions as a major adhesin, promoting bacterial attachment to human epithelial cells via binding to host extracellular matrix proteins, chiefly vitronectin and laminin[2][3]. These interactions support both colonization and invasion of host airway tissues—a key step in the pathogenesis of otitis media, chronic obstructive pulmonary disease (COPD) exacerbations, and other respiratory infections[3][4][7]. PE can also recruit host complement inhibitors, helping NTHi evade innate immune responses. As a result, PE is a focus for vaccine and immunotherapeutic development, showing immunogenicity and partial protection in preclinical studies, and is under clinical evaluation as a vaccine antigen in combination with other NTHi proteins[7]. Safety concerns are limited; main challenges relate to variable effectiveness of vaccines targeting PE, and inconsistent induction of protective or bactericidal antibodies in animal studies[1][7].

Other names

Protein EPEHaemophilus influenzae protein ENTHi PE

As a vaccine antigen, PE induces anti-PE antibodies to block adhesion and/or promote bacterial clearance. Inhibitors or blocking peptides can also interrupt PE-mediated host cell adhesion.