Porcine circovirus 2 (PCV2) is a single-stranded DNA virus that is non-enveloped with an unsegmented circular genome roughly 1.7-1.8 kb in length. PCV2 belongs to the family Circoviridae and represents the second member of the genus Circovirus of which there are four known variants. PCV2 was first isolated in 1997 and has been found to cause postweaning multisystemic wasting syndrome, which over time results in substantial depletion of lymphocytes. However, viral infection alone often produces mild disease; additional co-factors such as concurrent infection are necessary for the development of severe disease. PCV2 is an economically important disease present in every major swine-producing country in the world.