The invention relates to new porcine circovirus strains isolated from pulmonary or ganglionic samples obtained from farms affected by the post-weaning multisystemic wasting syndrome (PMWS). It relates to purified preparations of these strains, conventional attenuated or inactivated vaccines, recombinant live vaccines, plasmid vaccines and subunit vaccines, as well as reagents and diagnostic methods. It also relates to the DNA fragments which can be used for the production of subunits in an in vitro expression vector or as sequences to be integrated into a virus or plasmid type in vivo expression vector.