Relative fold change of ISG transcription (A–C) and viral RNA (D) by RT-qPCR. The study was conducted in head kidney from animals inoculated with VHSV isolates pathogenic (P) and non-pathogenic (NP) to sole. Poly I:C-inoculated animals were used as positive control. Bars indicate mean ± standard deviation (SD) obtained from three different samples. Different letters denote significant differences (p < 0.05) between groups at each sampling time and within the same group throughout the time. ND: Non-detected relative fold change with respect to the negative control group (L15, not represented in the graphic).