Nidovirales

Nidovirales is an order of viruses. It is carried by animals and humans. The order includes the families "Coronaviridae", "Arteriviridae," "Roniviridae," and "Mesoniviridae".
Nidoviruses are enveloped positive-sense single-stranded RNA viruses. Their name comes from the Latin word "nidus", meaning nest, as all viruses in this order produce a 3' co-terminal nested set of subgenomic mRNAs during infection.