RESEARCH d

to the Circoviridae family and is the causative infectious agent, together with other viral and bacterial pathogens, of the so-called porcine circovirus associated diseases (PCVD) [1,2]. Several in vitro and in vivo studies have confirmed that the virus interacts and modulates several components of the pig immune system, having its major tropism to the cells of the monocyte/macrophage lineage (MØ) and dendritic cells (DC). However, it seems that no efficient replication and spread derives from infection since the virus lacks its own polymerase for autonomous propagation. It was also demonstrated that lymphocytes, especially if activated to lymphoblasts, can carry PCV2 antigens and genome, thus representing additional target cells. The interaction with innate immune cells and/or with lymphocytes/lymphoblasts triggers virus replicatio