Expression and purification of recombinant feline interferon in the baculovirus-insect larvae system

•Feline interferon alpha 7 with and without 8xArg tag was expressed.•Expression was carried out in the baculovirus-Sf9 cells and insect larvae systems.•Rachiplusia nu was a better host than Spodoptera frugiperda for expression.•The 8xArg tag did not affect the interferon biological activity.•The 8xArg tag facilitated interferon purification by ion exchange chromatography.

Feline interferons (FeIFNs) are cytokines with antiviral, antitumor and immunomodulatory functions used as therapeutic agents in a variety of veterinary diseases. In this work, FeIFN-α7 and FeIFN-α7xArg containing eight residues of arginine were expressed in Sf9 cells and insect larvae. At 4 days post-infection (dpi), the concentrations of FeIFN-α7 and FeIFN-α7xArg in suspension culture were (1.28 ± 0.15) × 106 U ml−1 and (1.3 ± 0.2) × 106 U ml−1 respectively. The maximum expression levels of FeIFN-α7 and FeIFN-α7xArg were (3.7 ± 0.2) × 106 U ml−1 and (3.5 ± 0.4) × 106 U ml−1 at 2 dpi in Rachiplusia nu larvae and (1.1 ± 0.2) × 106 U ml−1 and (1.0 ± 0.15) × 106 U ml−1 at 5 dpi in Spodoptera frugiperda larvae respectively. R. nu was a better host for FeIFN-α7 and FeIFN-α7xArg expression. The 8xArg tag did not affect the biological activity of FeIFN-α7 and was useful to promote the FeIFN-α7xArg adsorption on ion exchange chromatography (IEC), allowing its purification in a single step from supernatant culture and R. nu larvae. FeIFN-α7xArg was purified from the larval extract with a yield of 70% and a purification factor of 25 free of viruses. We conclude that R. nu larvae are new low-cost hosts for the expression of recombinant FeIFN-α7.