Essentials of Glycobiology (IMAGE) Cold Spring Harbor Laboratory Caption Influenza A viruses initiate infection by binding to cell-surface sialic acids, via a hemagglutinin molecule. The cover of "Essentials of Glycobiology" shows the structure of HA (background) and diagrams of three different sialic acids and the associated receptor binding sites (foreground). Credit Cold Spring Harbor Laboratory Press Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.