The neuraminidase on the surface of the virion is necessary for new viral particles to break away from the host cell. Neuraminidase is a glycosidase (an enzyme that catalyzes the hydrolysis of glycosidic linkages) that specifically promotes the cleavage of sialic acid from glycoprotein saccharide chains. When the glycosidic linkage is cleaved by hydrolysis, the sialic acid falls off the cell surface. The viral particle is now no longer tethered to the host cell and can move off to infect other cells.