Birds (such as pigeons[1] and ducks[2]) and pigs[3] serve as natural hosts, though dogs have been shown to be infected as well.

Some members of this genus cause disease: PCV-1 is non pathogenic, while PCV-2 causes postweaning multisystemic wasting syndrome (PMWS).

[5][6] The following species are recognized: Viruses in Circovirus are non-enveloped, with icosahedral and round[clarification needed] geometries, and T=1 symmetry.

[5] The virions of Circoviruses are surprisingly small, with diameters ranging from 17 up to 22 nm.

The virus replicates through an dsDNA intermediate initiated by the Rep protein.