Gene delivery of albumin binding peptide-interferon-gamma fusion protein with improved pharmacokinetic properties and sustained biological activity

We have demonstrated that gene delivery of a fusion protein of mouse interferon (IFN) γ with mouse serum albumin (IFNγ–MSA) was effective in prolonging the circulation half-life of IFNγ in mice. However, the fusion to MSA greatly reduced the biological activity of IFNγ to less than 1%. In this study, we designed IFNγ fusion proteins with a 20 amino-acid long albumin-binding peptide (ABP) to prolong the in vivo half-life of IFNγ without reducing its biological activity. IFNγ–ABP and ABP–IFNγ, two fusion proteins with the ABP being fused to the C- or N-terminal of IFNγ, retained 40%–50% biological activities determined using a gamma-activated sequence-dependent luciferase assay. These fusion proteins exhibited the ability to bind to MSA. Gene delivery of IFNγ–ABP or ABP–IFNγ to mice using the hydrodynamic injection method resulted in a sustained concentration of IFNγ in the serum compared with gene delivery of IFNγ. In addition, the growth of mouse colon carcinoma CT-26 cells in the lung was efficiently inhibited by gene delivery of the IFNγ fusion proteins. These results indicate that the fusion of ABP is a useful approach to achieving prolonged retention in the blood circulation through binding to serum albumin and retaining biological activity.