Articles of Significant Interest Selected from This Issue by the Editors.

Deciphering the Cell-Invading Molecular Machinery of Porcine Deltacoronavirus Coronavirus spike proteins, which guide viral entry into cells, diverge among coronavirus genera. Shang et al. (e01556-17) and Xiong et al. (e01628-17) solved the cryo-electron microscopy (cryo-EM) structure of porcine deltacoronavirus spike proteins, which are closely related to those from the alphacoronavirus genus. Spike protein structural features facilitate evasion of host immune surveillance mechanisms. Shang et al. discovered that the spikes mediate receptor recognition and membrane fusion. Xiong et al. found that the protein is adapted to enteric infection and resistant to premature activation from enteric proteases. These studies elucidate new features of coronavirus structure, function, and evolution.