豬第二型環狀病毒（PCV2）為最小且含單股環狀去氧核醣核酸基因組的無封套病毒，該病毒常造成養豬產業的重大經濟損失。

Porcine circovirus 2 (PCV2) is a small, non-enveloped virus with a single-strand circular DNA genome that has had severe impact on the swine industry.