The differential expression of Mx1, Mx2, OAS-1, PKR and RNaseL at 6, 12, 24 and 48 hrs post-transfection is shown as the mean of four replicates. The swine macrophage cell-line, 3D4/31, was transfected with constructs expressing the TTSuV1 ORF1 or ORF. Values ≥ 2 two-fold changes when compared to control cells transfected with the empty vector are considered significant (solid line). No significant regulation was detected in cells transfected with the TTSuV1 ORF2 expression plasmid (data not shown). * p ≤ 0.05.