[Construction of recombinant fowlpox virus expressing chicken IL-2 and assay of biologic activity of the product in vitro].

In order to determine the adjuvant effects of the chicken IL-2 (ChIL-2) on new generation vaccines, ChIL-2 gene was amplified from ConA-stimulated chicken spleen cells by RT-PCR and was directionally inserted into fowlpox virus (FPV) transferring vector p1175 under the control of FPV early/late promoter (PE/L), resulting in recombinant transferring vector p1175IL2. Then the p1175IL2 plasmid was transfected into chicken embryo fibroblasts (CEF) pre-infected with wild type FPV to generate recombinant fowlpox virus expressing ChIL-2 (rFPV-IL2). By selection of blue plaques on the CEF, overlaid with agar containing X-gal, rFPV-IL2 was obtained and purified. The supernatant from CEF monolayer infected with rFPV-IL2 (M.O.I2.0) after 72 hours was detected for the production of ChIL-2 by XTT/PMS colorimetric assay. About 3.6 x 10(5) u/mL of specific ChIL-2 activity was determined. The results show that rFPV-IL2 can express ChIL-2 effectively. rFPV-IL2 provides us with an effective tool for studying avian immunology as well as a potential vaccine-enhancing agent.