High level expression of biologically active canine Interferon-α subtype 4 using a baculovirus

In this study, a high amount of bioactive recombinant canine interferon-a subtype 4 (CaIFN-alpha 4) was expressed in a baculovirus system. For easy purification, it was expressed as a CaIFN-alpha 4 bearing histidine hexamer at the C-terminal region, designated CaIFN-alpha 4His. CaIFN-alpha 4His was detected in culture supernatants of insect cells infected with the recombinant virus using sodium dodecyl sulfate-polyarcylamide gel electrophoresis (SDS-PAGE) and Coomassie Brilliant Blue staining. The level of expression was very high, and approximately I mg of purified protein, with 5.0 x 10(7) units/mg, was obtained from 300 ml of culture supernatant. The purified product showed antiviral activity against Vesicular stomatitis virus on canine tumor cell line A72 and chicken embryo fibroblast cells.