The genome of porcine circoviruses consists of circular and single-stranded DNA molecules,there are many open reading frames(ORFs)in the genome,of which,the two main ORFs encode the Rep protein which is involved with the replication of porcine circovirus and the Cap protein:Rep and Rep′ bind to double-stranded DNA fragments comprising of the origin of replication of PCV,but the binding sites of the two proteins are distinct.The Rep protein alone could not initiate the replication of the virus,while Rep and ...