Abstract
Fish interferon (FIFN) is expected to have a potential to play an important role in the prevention of viral infections in fish farming. Since a very small amount of FIFN is produced in fish body, it is quite difficult to purify it. Therefore, we first tried to immortalize lymphocytes of the Japanese flounder using a variety of oncogenes and found that the cotransfection of c-Ha-ras and c-fos was most effective. One of these immortalized lymphocyte cell lines, HL8, produced FIFN which was a glycoprotein of about 16kDa. The cloned FIFN cDNA is composed of a signal peptide region coding 30 amino acids and a structure gene coding a 108 amino acid chain including a potential Asn-linked glycosilation site. Therecombinant FIFN (rFIFN) produced by mammalian BHK-21 cells inhibited the propagation of threefish viruses in cell lines and infection with hirame rhabdovirus in rainbow trout by oral administration.The minimum effective amount of the rFIFN was 200pg/g-body weight.
