Prokaryotic-expressed porcine IFNα1-THYα1 fusion proteins exert IFN and THY activities in vitro.

Combined use of interferon (IFN) and thymosin (THY) holds a stronger antiviral effect than when applied individually because of their coordination and complementary action. In this study, prokaryotic expressed porcine IFNα1 (poIFNα1) or the porcine IFNα1-THYα1 fusion protein coding with the Escherichia coli preferred codon sequences connected by the three different linkers were gained in the unlabeled pRSFDDuet-1 expression systems and purified using the strong anion-exchange chromatography and hydrophobic chromatography (among which, one was digested by thrombin because the cleavage site was included in the linker). Then, the activities of IFN and THY in the fusion protein were detected using the cytopathic effect inhibition assay and T-cell activity assays. SDS PAGE and western blotting results showed that the poIFNα1 or the three poIFNα1-THYα1 fusion proteins with three different linkers were expressed solubly in E. coli. The poIFNα1 protein and three types of poIFNα1-THYα1 fusion proteins with >90% purity were gained. The poIFNα1-LinkerB-THYα1 fusion protein showed the highest interferon activity compared with the others (P < 0.001), and the poIFNα1-LinkerA-THYα1 fusion protein highest thymosin activity (P < 0.05). In this study, a preliminary experiment was conducted for the expression of the poIFNα1 and THYα1 fusion proteins.