| Fusion protein is the main protective antigen of NDV and determines the virulence of the virus. It is of importance getting effective NDV genetic engineering vaccine. The study mainly involves in constructing recombinant fowlpox virus and evaluating the immunogenicity of the recombinant fowlpox virus.1. The fowlpox virus (FPV) transfer vector pEF-2 was constructed by cloning the F gene of the NDV F48E8 strain in the gene of Ecogpt of FPV insertion vector PEFgptl2S, downstream of VVp7.5 promoter. The secondary CEF cells were transfected with pEF-2 which had been infected with a recombinant virus, rFPV-NDV expressing F protein for 3 hours to produce the new recombinant virus with two F protein gene named as rFPV-2. virus plaque was selected by using limiting dilution. rFPV-2 was obtained with MXHAT medium which could prevent its growth but not rFPV-NDV. it is confirmed expressing more NDV fusion protein by indirected immunofluorescence assay compared with rFPV-NDV.2. The recombinant virus, rFPV-2 was used to immune 9-day-old SPF chickens. The immunogenicity was evaluated based on the antibody response after immunizations and the protectin of vaccinated chickens against challenge with virulent NDV strain F48E8. The results indicated that The recombinant virus could induced antibody responses and protective immune responses. In SPF chickens which were inoculated with rFPV-2, the protective rate was 50 % .Two inoculations of rFPV-2 with 10 days interval in SPF chickens could protect 80% of chickens against challenge.
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