Infection studies on human cell lines with porcine circovirus type 1 and porcine circovirus type 2

Background: The lack of human donor organs in allotransplantation has led to a proposal for the use of porcine tissues and organs as alternative therapeutic material for humans. Besides immunological problems like graft rejection, one of the major concerns is the transmission of porcine microorganisms as viruses, bacteria and fungi to a human recipient. Methods: Human cell lines have been infected with porcine circovirus type 1 (PCV1) and porcine circovirus type 2 (PCV2) to investigate whether PCV can infect and replicate in human epithelial cells and lymphocytes. Infection of PCV1 was observed with 293, Hela and Chang liver cells, infection with PCV2 only in Rd cells. In addition, religated viral DNA of PCV1 and PCV2 has been used to transfect adherent human cell lines. Results: PCV1 persisted in most cell lines without causing any visible changes, while PCV2-transfected cells showed a cytopathogenic effect. Presence of PCV DNA was detected in cells and supernatant by PCR, expression of viral proteins by an indirect immune fluorescence assay. A replication assay showed that the replication of PCV DNA was initiated at the origin of replication. When virus-free cells were inoculated with the supernatant of PCV-infected human cells, the infection was not passed. Conclusion: Although PCV gene expression and replication took place in human cells, the infection is non-productive. Alteration of protein localization suggests that protein targeting may be disturbed in human cells.