Innate immune responses to replication of porcine reproductive and respiratory syndrome virus in isolated Swine alveolar macrophages.

Porcine reproductive and respiratory syndrome (PRRS) is an infectious disease caused by a positive RNA strand arterivirus. PRRS virus (PRRSV) interacts primarily with lung macrophages. Identifying the genetic components involved in host resistance/susceptibility would represent an important step forward in the design of disease control programs. In this study, alveolar macrophages derived from five commercial pig lines were used to study the innate immune response to PRRSV infection in vitro. Analysis by flow cytometry has demonstrated that bronchial alveolar lavage fluid (BALF) preparations were almost exclusively composed of alveolar macrophages and that the pigs tested were free from infection. Macrophages from the Landrace line showed significantly reduced virus replication and poor growth of PRRSV during 30 h of infection. By 72 h, PRRSV viral load was down to 2.5 log10 TCID50 compared with an average of 5 log10 TCID50 for the other breeds tested. These observations suggest that factors intrinsic to ...