Sialic acid: Sialic acid is a 9-carbon monosaccharide derivative. The name comes from the Greek σιαλοσ (sialos) 'saliva'. This is a negatively charged ion that gives saliva a smooth sensation. Not only is it known to "induce" invading bacteria, it is now known to be a transmitter of gangliosides and a component of the brain. Sialic acid prevents germs from invading. Sialic acid is also a receptor for influenza viruses and a binding site for influenza viruses to bind to mucus cells.