The Viruses
   The RNA Viruses
     The Positive Stranded ssRNA Viruses
       Order Nidovirales
         Family Arteriviridae [monotypic]
           Genus Arterivirus
             1 Equine arteritis virusᵀ
             2 Lactate dehydrogenase-elevating virus
             3 Porcine respiratory and reproductive syndrome virus
             4 Simian hemorrhagic fever virus