Glycerophosphodiester phosphodiesterase (Protein D) (PD)

Protein D is a highly conserved 42-kDa surface lipoprotein found in both encapsulated and non-typeable Haemophilus influenzae (NTHi) (UniProt: P14422). It functions as a glycerophosphodiester phosphodiesterase (GlpQ), which is essential for the hydrolysis of glycerophosphodiesters into glycerol-3-phosphate, facilitating the uptake of choline required for cell wall synthesis (PubMed: 10417340). In addition to its metabolic role, Protein D acts as an adhesin that promotes bacterial colonization of the human respiratory tract and exhibits a unique affinity for human immunoglobulin D (IgD) (PubMed: 2181456). Because of its high conservation across NTHi strains, it has been developed as a vaccine candidate and is currently utilized as a carrier protein in the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) (PubMed: 19622518). This dual-purpose application aims to provide protection against both Streptococcus pneumoniae and NTHi-induced conditions such as acute otitis media and exacerbations of chronic obstructive pulmonary disease (COPD).

Other names

Protein DhpdGlpQIgD-binding proteinSurface lipoprotein D

Acts as a vaccine antigen to induce neutralizing antibodies and as a carrier protein to enhance the immunogenicity of conjugated polysaccharides.