Over-expression in Pichia pastoris and Properties of Human Serum Albumin-interferon α2b Chimera

To reduce the serum clearance of interferon α2b, a chimerical gene encoding a human serum albumin (HSA)-human interferon α2b (IFNα2b) fusion protein was over expressed in Pichia pastoris. After fermenting it in a 5 L bioreactor, the fusion protein, capable of cross-reacting with anti-IFN α and anti-HSA antibody, was purified from the culture of the recombinant yeast by ultra-filtration, Blue Sepharose affinity, phenyl hydrophobic interaction and Q ion exchange chromatography. Its IFNα2b moiety exhibits antiviral activity similar to those of recombinant human IFNα2b. In Cynomolgus monkey model, the fusion protein was detectable in plasma, even 336 h after a single dose of 90 μg/kg was injected intravenously or subcutaneously. The elimination phase half-life of the fusion protein was 101 h after intravenous injection and 68.2 h after subcutaneous injection. Its subcutaneous bioavailability was 67.9 %. The enhanced pharmacokinetics of interferon α2b fused to human serum albumin suggests its promising application in clinical medicine.