The coronaviruses are ssRNA viruses that infect a wide range of mammalian and avian species; they are important causes of respiratory and enteric disease, encephalomyelitis, hepatitis, serositis and vasculitis domestic animals. In humans coronaviruses are one of several groups of viruses that cause the common cold. The genus Coronavirus together with the genus Torovirus from the family Coronaviridae; members of these two genera are similar morphologically. The Coronaviridae, Arteriviridae, and Roniviridae are within the order Nidovirales. Seven coronaviruses are known to infect humans, three...