Expression of biologically active recombinant equine interferon-gamma in Escherichia coli

Interferon gamma (IFN-gamma) is a pleiotropic cytokine that is recognized as an important modulator of the immune response. To date, there is no report that prokaryocyte-derived recombinant equine IFN-gamma has antiviral activity. In this report, the gene coding equine IFN-gamma (EIFN-gamma) mature protein was cloned into pET-28a (+) and the recombinant EIFN-gamma was expressed in Escherichia coli (E. coli). The antiviral activity of expressed recombinant EIFN-gamma was evaluated by using a recombinant Vesicular Stomatitis Virus expressing green fluorescence protein (rVSV-GFP) system in the equine fetal kidney-78 cell line (EFK-78). The GFP expression in the EFK-78 cells dramatically decreased in the cells treated with EIFN-gamma in a dose-dependent manner, comparing with the mock-treated cells. The titer of antiviral activity was 1 x 10(3)AU/ml. These results demonstrated that the EIFN-gamma expressed in this study had good biological activity. Pure forms and sufficient quantities of biologically active IFN-gamma could facilitate the study of its activities in modulating immune responses both in vivo and in vitro.