Viruses of the order Nidovirales are large, enveloped, single-stranded RNA viruses. Among others, this order includes the families Arteriviridae and Coronaviridae. The nidoviruses detected in snakes are most closely related to the family Coronaviridae, subfamily Torovirinae.Nidoviruses (genus Pregatovirus) are found in pythons and boas, and have most commonly been detected in ball pythons and green tree pythons so far. They are associated with pneumonia and stomatitis and seem to be important pathogens in different python species.
Nidoviruses have also been detected in shingleback lizards and other Tiliqua spp. However, these are clearly different from the nidoviruses described in snakes and are called shingleback nidovirus 1 (genus Tiruvirus). Infection is associated with respiratory disease.