The main obstacles to using Interferon a1 as an antiviral agent are its low stability and fast clearance. Here, we prepared a long-lasting recombinant human serum albumin-interferon alpha 1 fusion protein. It was expressed in methylotrophic yeast Pichia pastoris with HSA's natural signal peptide and purified by dye affinity chromatography and ion exchange chromatography. The physicochemical, biological, and pharmaceutical characteristics of HSA-IFN alpha 1 were then evaluated in vitro and in vivo. The purity of HSA-IFN alpha 1 was about 95% analyzed by SDS-PAGE. Molecular weight determined by MALDI-TOF mass spectrometry was 86,582. Western blot analysis showed that the expressed HSA-IFN alpha 1 had the antigenicity of HSA. The N-terminal acid amino sequence was identical to predicted sequence. The antivirus activity in vitro evaluated by cytopathic effect assay was (1.63 +/- 0.06) x 10(5) IU/mg. After administered in rats, the biological activity of HSA-IFN alpha 1 were enhanced and maintained for 6 days in serum. Overall, these studies demonstrate the feasibility of using albumin-fusion technology to development a long-lasting, antiviral protein HSA-IFN alpha 1 with high antivirus activity. (C) 2013 Elsevier Inc. All rights reserved.