Human parainfluenza virus type 3 hemagglutinin-neuraminidase glycoprotein (HN (Hemagglutinin-neuraminidase))

The **Human parainfluenza virus type 3 hemagglutinin-neuraminidase glycoprotein (HN)** is a multifunctional viral envelope protein essential for the infectivity of HPIV3, an important cause of lower respiratory tract illness in infants and children[1][6]. HN mediates both **binding to sialic acid-containing receptors** on host cells (hemagglutinin function) and **enzymatic cleavage of sialic acid** (neuraminidase function), facilitating viral entry, dissemination, and release[3][6]. Structurally, HN is a type II membrane glycoprotein that forms homodimers, with a flexible active site that switches between receptor binding and catalysis[2][3]. The protein is moderately hydrophobic, contains N-glycosylation sites, and is related to neuraminidases found in other paramyxoviruses, like Newcastle disease virus[1][3]. Targeting HN with inhibitors or neutralizing antibodies is a therapeutic strategy under investigation for HPIV3 infection, although no HN-specific drugs are currently approved[6][4]. The protein’s dual activities and structural complexity present unique challenges and opportunities for antiviral drug and vaccine development[3][6].

Other names

HPIV3 HNhPIV3 HNHuman parainfluenza virus type 3 HN protein

Inhibition of neuraminidase activity, preventing viral release and spread Blocking receptor binding, preventing viral attachment/entry Stabilization of a receptor-bound or catalytic intermediate state, reducing viral infectivity