Project title: Interaction of PRRSV and Porcine Dendritic Cells: Potential Role in Viral Persistence

Institution: National Animal Disease Center, USDA/ARS

Outcomes/Results: One type of white blood cell called a “dendritic cell” from the lung is difficult to infect with PRRS in the laboratory and they couldn’t be tracked to other tissues in the body.

Porcine reproductive and respiratory syndrome virus (PRRSV) may persist in tissues of pigs for months. How the virus persists in certain pigs remains to be determined. It is possible that one type of white blood cell traps the virus allowing it to remain in host tissues undetected by the immune system. We have provided the first isolation and characterization of a specific type of white blood cell(called a dendritic cell) in the lung of pigs which may play a role in early contact with PRRSV. These cells were distinct compared to similar cells derived in the laboratory. Our data indicates that these cells from the lung are less susceptible to viral infection than the laboratory derived cells. We next sought to determine whether we could track the movement of cells to the other tissue in the body using the dye carboxyfluorescein diacetate succinimidyl ester (CFSE). We were unable to detect labeled cells in the tissues. The use of other appropriate dyes should be considered. While the findings of the present study indicate lung dendritic cells may not be productively infected with PRRSV, this does not rule out their role in transporting the virus from the lung to other tissues.