The two surface glycoproteins of the mumps virus are the hemagglutinin-neuraminidase (HN) and Fusion proteins. These glycoproteins are essential for viral entry to host cells, and the spread of newly formed virions. The HN protein is a 582-amino acid structural glycoprotein of the mumps virus. HN is a type II membrane protein in which the N terminus is oriented towards the cytoplasm and the C terminus is extracellular.The HN protein exhibits both hemagglutinin and neuraminidase properties and is critical for membrane fusion and viral entry into host cells.