Members of the subfamily Simarterivirinae have only been detected in African monkeys. Members of this subfamily are distinguished by the presence of four additional open reading frames downstream of the ORF1b replicase that are not present in members of other arterivirus subfamilies. Members of the Simarterivirinae also have three papain like protease proteins, nsp1α, nsp1β, and nsp1g.
Genus demarcation criteria
See “Subfamily, genus and species demarcation criteria” section on the family for species demarcation criteria which are universal for all subfamilies.