Abstract：To investigate immuno-enhancement activity of chicken interleukin-2 (IL-2) to Newcastle disease virus (NDV) F protein, NDV F gene was linked with chicken IL-2 via 7-amino acid glycine-rich linker(G2SG3S) by SOE-PCR(splicing by overlap extension-PCR) technique and then inserted into pcDNA3.1(+) and constructed the recombinant plasmid pcDNA-IL2-F which was transfected into chicken embryo fibroblast cells with liposome. The recombinant poteins were expressed correctly with molecular mass of 76.0 kD and 59.6 kD. The results of Western blotting analysis indicated that the interest proteins(pcDNA-IL-2-F and pcDNA-F) were recognized specifically by antisera against NDV. SPF chickens(Gallus domedticus), and were divided into 5 groups and immunized by recombinant plasmid pcDNA-IL-2-F, pcDNA-IL-2 mixing pcDNA-F, pcDNA-F, Lasota vaccine and plasmid pcDNA-3.1(+), respectively. The sera of each group were collected weekly for detecting antibodies of immunized chickens by ELISA. The results suggested that SPF chickens immunized pcDNA-IL-2-F exhibited stronger antibody response(P <0.05) than that of both the group immunized mixing pcDNA-F with pcDNA-IL-2 and the group immuned pcDNA-F. The SPF chickens were challenged with NDV F48E9 on the 20th day post immunization and the protective rate of the group immunized pcDNA-IL-2-F was higher than that of other plasmid groups. These results revealed that expression of tandem genes of NDV F and Chicken IL-2 could provide an optional immune response that in turn protected chickens from NDV challenge than that of sigle NDV F gene. In general, the vaccine strategy described in this study can provide a good platform for future desire of virus vaccine.
