IFNA1 and infection: Consistently, the mRNA level of isg15, a typical ISG gene, was also significantly upregulated and reached the peak at 1 day in the liver, spleen and kidney (Figure 3I,K) or 3 days (in gill, Figure 3L) post GCRV infection (dpi) and then returned to the initial level, indicating that the challenge experiment successfully induced an IFN response.