The PRRS virus belongs to the group of Arteriviruses.Other members of this group are:
A characteristic of the Arteriviruses is their method and primary site of replication. Arteriviruses replicate in the perinuclear cytoplasm of their host cells. New virions are released by exocytosis from the surface of the cell. The primary target cell of the virus is the alveolar macrophage of the pig.