A model of an S-protein. (IMAGE) Lehigh University Caption A model of an S-protein. Credit Illustration: Dr. Yeolkyo Choi/Lehigh Univesity 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.