Abstract: In order to establish a stable,simple and rapid detection method to estimate the activities of the recombinant chicken interferon-α/interleukin-2 fusion protein (rChIFN-α-Linker-ChIL-2,recombinant fusion protein) in vitro,the activities of rChIFN-α-Linker-ChIL-2 were estimated by detecting its specific immune response to monoclonal antibody (MAb) against ChIFN-α and ChIL-2 by ELISA assay.The antiviral activities of rChIFN-α-Linker-ChIL-2 protein were tested by inhibiting the 50% appearance of cytopathic effect (CPE) of vesicular stomatitis virus (VSV) and infectious bursal disease virus (IBDV) on the passage cell lines DF1.The promoting proliferation activities of lymphocytes in the chicken peripheral blood and spleen of recombinant fusion protein were tested by MTS method.The results showed that rChIFN-α-Linker-ChIL-2 protein had the ability of specific immune response to anti-ChIFN-α MAb and anti-ChIL-2 MAb,respectively.The antiviral activity of rChIFN-α-Linker-ChIL-2 protein inhibiting the reproduction of VSV on DF1 cell line was higher than IBDV,and both of the antiviral activities of recombinant fusion protein against VSV and IBDV were much higher than the recombinant ChIFN-α protein (rChIFN-α) control.The recombinant fusion protein had apparent promoting proliferation activity of lymphocytes in the chicken peripheral blood and spleen,which were much higher than that of the rChIFN-α control.The study suggested that the activities detection and estimation methods of the recombinant fusion protein in vitro were successfully established,which laid the foundation for the further study of the synergy activity of recombinant fusion protein in vivo.

Key words: chicken interferon-α; chicken interleukin-2; recombinant fusion protein; in vitro activity