ISG15 and infection: The PRRSV only infection group had the largest gene total at 3 dpi leading to a large number of affected pathways and processes that included upregulated genes falling into categories such as positive regulation of immune effector process(GO: 0002699), negative regulation of viral process (GO: 0048525), neutrophil chemotaxis (GO: 0030593), and ISG15 antiviral mechanism (REAC:R-SSC-1169408).