Pestiviruses, animal pathogens related to hepatitis C virus, are a major global health threat. They deliver their genome into hosts’ cells by fusing their envelope with the cell membrane. In April, in Proceedings of the National Academy of Sciences, Associate Professor of Molecular Biophysics and Biochemistry Yorgo Modis and colleagues published the crystal structure of glycoprotein E2 from a pestivirus known as BVDV. Here, the glycoprotein (blue and purple) is seen on the viral envelope (gray), poised to fuse with a host cell membrane.