Immunoprotection of grass carp (Ctenopharyngodon idella) with recombinant interferon (rCiIFN) against GCHV infection

► Grass carp recombinant interferon (rCiIFN) was expressed and purified from E. coli. ► In vitro and in vivo protective effects of rCiIFN against GCHV infection were analyzed. ► The effective regimen of rCiIFN immunoprotection by ip and oral routes was determined. ► ISGs were greatly up-regulated after treatment with rCiIFN by ip and oral routes.