Hemagglutinin-neuraminidase (HN) protein (HN)

The hemagglutinin-neuraminidase (HN) is a surface glycoprotein of parainfluenza viruses that performs dual roles in viral infection: receptor binding and receptor destruction. Structurally, HN is an oligomeric transmembrane protein composed of a short intracellular domain, a transmembrane region, and a large ectodomain comprising a helical stalk and a globular head domain with a six-bladed beta-propeller fold. The protein binds sialic acid receptors on host cells through its globular head domain—an essential first step in viral attachment and infection. Once bound, HN undergoes conformational changes that activate the viral fusion protein (F), which catalyzes membrane fusion and viral entry. After viral replication, HN's neuraminidase activity cleaves sialic acid receptors, facilitating release of progeny virions. Due to its critical roles in both viral entry and egress, HN represents a promising therapeutic target for antiviral drugs and vaccines designed to prevent parainfluenza infections.

Other names

Hemagglutinin-neuraminidase glycoproteinAttachment proteinReceptor-binding proteinNA (neuraminidase)

Receptor binding inhibition: Blocking sialic acid receptor engagement to prevent viral attachment; Neuraminidase inhibition: Preventing sialic acid cleavage, reducing viral egress and spread; Fusion inhibition: Interfering with HN-F protein interactions required for membrane fusion.