Four molecules of neuraminidase form a 'corner' in the virus coat. Neuraminidase cuts through the host cell surface to enable the virus to disperse and infect other cells. The enzyme is inhibited by drugs such as zanamivir (Tamifu, shown in cyan with the enzyme in green) and oseltamivir (shown in pink with enzyme in lemon). The hydrogen bonding of zanamivir is shown.

The structures are superposed with SSM. The residues of the binding site can be selected quickly using the Neighbourhood selection option.