Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2007
Publication Date: 7/20/2007
Citation: Yu, S., Vincent, A., Opriessnig, T., Carpenter, S., Kitikoon, P., Halbur, P.G., Thacker, E. 2007. Quantification of PCV2 capsid transcript in peripheral blood mononuclear cells (PBMCs) in vitro. Veterinary Microbiology. 123:34-42. Interpretive Summary: Porcine circovirus Type 2 (PCV2) is a significant swine pathogen worldwide, however the manner in which it causes disease is unknown. To better understand the virus, assays to study virus replication in different populations of swine immune cells were developed. This study showed that certain populations of cells are preferred for PCV2 replication, especially when chemically activated. Since the cell populations identified to contain replicating PCV2 are also critical in fighting infection, these infected immune cells are likely to play a role in the development of porcine circovirus associated disease (PCVAD). The information provided by this study serves as a foundation for future research to further understand PCVAD and methods to prevent or intervene with the progression of disease.
Technical Abstract: The presence of PCV2 DNA or spliced capsid mRNA (Cap mRNA) for viral replication was assessed following addition of PCV2 to resting or concanavalin A (ConA) stimulated peripheral blood mononuclear cells (PBMCs). Real-time PCR or real-time RT-PCR assays were used to measure viral DNA or Cap mRNA, respectively. The study demonstrated that PCV2 replication increased in infected PBMCs over time. Replication within infected PBMCs was significantly (P < 0.05) increased when PBMCs were stimulated with ConA, compared to unstimulated PBMCs. The data showed a strong correlation between the level of PCV2 Cap mRNA and the level of viral DNA in the ConA stimulated PBMCs. Replication of PCV2 was also assessed in T lymphocyte- and monocyte/macrophage-enriched or monocyte/macrophage-depleted PBMC populations which had been stimulated with ConA for 3 days. It was demonstrated that the enriched T lymphocytes and the monocyte/macrophage-depleted PBMCs had significantly higher Cap mRNA and viral DNA levels (P < 0.05) compared to the monocyte/macrophage-enriched population, indicating that in addition to monocytes/macrophages, PCV2 replicates in lymphocytes, particularly T lymphocytes following stimulation. These results suggest that the presence of activated T lymphocytes may play an important role in PCV2 replication and potentially the development of clinical disease.