Norovirus Micrograph (IMAGE) Washington University School of Medicine Caption Researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus -- shown here in a colored transmission electron micrograph -- uses to invade cells. Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease because the virus grows poorly in the lab. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine. Credit CDC/Charles D. Humphrey 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.