Hemagglutinin-Neuraminidase Protein (HN)

The hemagglutinin-neuraminidase (HN) protein is a multifunctional viral surface glycoprotein found in several paramyxoviruses. It combines both hemagglutinin and neuraminidase activities within a single polypeptide. HN binds to sialic acid-containing receptors on the surface of host cells (hemagglutinin activity), facilitating viral attachment and entry. It also possesses neuraminidase activity, hydrolyzing terminal sialic acid residues, enabling the release of progeny virions from infected cells. Upon receptor binding, HN undergoes conformational changes that trigger activation of the fusion (F) protein, leading to membrane fusion between the virus and host cell.

HN inhibitors block either attachment or release steps in infection cycles.