ISG15 and infection: In non-vaccinated animals, a higher antiviral interferon-related response was only detected early on in the infection (24 hours pi), with the up-regulation of irf9, pkr, isg15, mx1, and mx2 (FC values of 2.15, 0.81, 0.89, 1.29, and 1.74, respectively) in comparison to vaccinated and mock-vaccinated groups.