“…As an enveloped, positive-stranded RNA virus, PRRSV belongs to the order Nidovirales , family Arteriviridae , genus Betaarterivirus and can be classified into two species, Betaarterivirus suid 1 (PRRSV 1, formerly called the European type) and Betaarterivirus suid 2 (PRRSV 2, formerly called the North American type), with approximately 44% genetic differences between each other [ 4 , 5 ]. Both PRRSV strains manifest the same clinical signs in naïve sows and gilts [ 6 ]. In Taiwan, the first outbreak of PRRSV 2 was reported in 1993 [ 7 ].…”