Haemophilus influenzae d

Haemophilus influenzae (Hi) is a kind of pathogen that colonizes the human upper respiratory tract mucosa. According to the presence or absence of capsule, Hi can be divided into two categories: capsular Hi, which mainly causes invasive diseases; Type Hi, or non-typeable Hiemophilus influenzae (NTHi), mainly causes mucosal infection. The capsular Hi can invade human capillaries through the nasopharynx epithelium, and its outer polysaccharide capsule resists phagocytosis and complement-mediated lysis.
Haemophilus influe (tzae, Hi) Protein D (PD) is a highly conserved surface lipoprotein with a relative molecular mass of 42,000, present in all separable Hi and non-typeable Hiemophilus influenzae. , NTHi), is a bacterial virulence factor with glycerophosphodiesterase activity, which can cause the release of phosphocholine from host epithelial cells and plays an important role in Hi-induced respiratory infection. The pneumococcal polysaccharide conjugate vaccine using NTHi PD as a carrier protein not only prevents pneumococcal otitis, but also has an preventive effect on acute otitis media caused by NTHi. To date, PD is the first NTHi antigen that induces a protective response in the human body and is the most promising polysaccharide conjugate vaccine candidate carrier protein.