Coronaviruses and arteriviruses have emerged as major virus families relevant in ani mal and human health. The order Nidovirales, which includes the Coronaviridae and Ar teriviridae, was recognized by the International Committee for the Taxonomy of Viruses (ICTV) in 1996 based on the striking features common to the two virus families. In accord ance with this decision, the organizers of the coronavirus meeting, held every three years since 1980, invited colleagues working with both virus families to attend the VIIth Interna tional Symposium on Coronaviruses and Arteriviruses, held in Segovia,...