Expression,Purification and Anti-HBV Effect of Mutant Interferon-τ

Objective To express mutant interferon-τ(IFN-τ)in Pichia pastoris,purify the expressed product and study its anti-HBV effect.Methods Substitute the 6 amino acids in sheep IFN-τ sequence to the responding amino acids in human IFN-α,and clone the synthetic gene to plasmid pPICZα.Transform the constructed recombinant plasmid pPICZα-IFN-τ for expression of mu-tant IFN-τ to Pichia pastoris,for high density fermentation.The fermentation supernatant was concentrated by ultrafiltration,purified by ion exchange and molecular chromatography and determined for biological activity.Evaluate the anti-HBV effect of expressed pro-tein and compare with that of commercial IFN-α2a.Results The expression level of IFN-τ in fermentation supernatant was 400 ～ 500 mg / L.The expressed product contained more than 40% of total protein in supernatant and reached a recovery rate of 31.4%,a purity of about 95% and a specific activity of 2.1×107 IU / mg.The anti-HBV effect of the expressed IFN-τ was equal to,while the cyto-toxicity was lower than that of commercial IFN-α2a.Conclusion Mutant IFN-τ with high biological activity was successfully ex-pressed in Pichia pastoris,,which showed significantly inhibitory effect on HBV and low cytotoxicity.