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-α subtype 4 (CaIFN-α4) was expressed in a baculovirus system. For easy purification, it was expressed as a CaIFN-α4 bearing histidine hexamer at the C-terminal region, designated CaIFN-α4His. CaIFN-α4His 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 1 mg of purified protein, with 5.0 × 107 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.