Non-typeable Haemophilus influenzae surface antigens (NTHi surface antigens)

Non-typeable Haemophilus influenzae (NTHi) surface antigens are a heterogeneous collection of proteins and lipooligosaccharides located on the outer membrane of non-encapsulated H. influenzae strains. Unlike the encapsulated type b (Hib) strains, NTHi lacks a polysaccharide capsule, making its surface-exposed proteins—such as Protein D, Protein E, Pilin A, and various Outer Membrane Proteins (OMPs like P2, P5, and P6)—the primary targets for the host immune system and vaccine development [1, 9, 14]. These antigens play critical roles in bacterial pathogenesis, facilitating adherence to the respiratory epithelium, colonization of the nasopharynx, and evasion of host complement-mediated killing [17, 20]. NTHi is a leading cause of mucosal infections, including acute otitis media in children and acute exacerbations of chronic obstructive pulmonary disease (COPD) in adults [7, 21]. Therapeutic strategies focus on utilizing conserved surface antigens in multivalent vaccines, such as the NTHi-Mcat candidate and the Protein D-containing pneumococcal conjugate vaccine (Synflorix), to induce protective antibodies that block colonization and promote opsonophagocytic clearance [3, 15]. Despite their potential, the high genetic and antigenic diversity among NTHi strains remains a significant challenge for achieving broad-spectrum protection [1, 23].

Other names

NTHi surface proteinsNon-typeable Haemophilus influenzae outer membrane proteinsNTHi antigensNTHi adhesinsNon-encapsulated Haemophilus influenzae surface antigensNTHi OMPs

Induction of antigen-specific neutralizing and opsonophagocytic antibodies to prevent bacterial adhesion, colonization of the respiratory tract, and to facilitate immune-mediated clearance of the pathogen.