Porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, is the etiologic agent of an infectious disease of that name, characterized by respiratory disorders, abortion in pregnant sows and high mortality in piglets, resulting in significant economic losses in the pig industry worldwide. In order to identify whether genetic differences in PRRSV response may exist in pigs, alveolar macrophages were used to assess the progression of the type-I interferon (IFN) transcript response in porcine alveolar macrophages infected by PRRSV. Our results suggest that a dynamic differential regulation of the type-I IFN and chemokine transcripts may operate during the first hours of infection with and entry of the virus in alveolar macrophages, and provide a compelling mechanism for the establishment of PRRSV replication in susceptible cells.