Recombinant Fowlpox Virus Coexpressing HA from Subtype H_9N_2 of Avian Influenza Virus and Chicken Type II Interferon and Its Protective Efficacy Against Homologous Challenge in Chickens
The hemagglutinin (HA) gene from subtype H 9N 2 avian influenza virus and the chicken type Ⅱ interferon (IFN-Ⅱ) gene were directionally inserted into transferring vector 1175,resulting in recombinant transferring vector 1175HAIFN.Then the recombinant transferring vector 1175HAIFN was used to transfect the chicken embryo fibroblasts (CEF),which was pre-infected with wild type fowlpox virus,to generate recombinant fowlpox virus coexpressing HA and IFN-Ⅱ(rFPV-HA-IFN-Ⅱ).By selection of blue plaques on the CEF,overlaid with agar containing X-gal,rFPV-HA-IFN-Ⅱ was obtained and purified.The in vitro expression of HA by rFPV-HA-IFN-Ⅱ was detected in the recombinant virus-infected CEF with indirect immunofluorescence and expression of IFN-Ⅱ was confirmed by detection of the suppressive effect of IFN-Ⅱ on the VSV-induced cytopathic effect.Experiments on chickens demonstrated that rFPV-HA-IFN-Ⅱ had the same protective efficacy to suppress SPF chickens or commercial broiler chickens from shedding challenged virus as inactivated vaccine and had the ability to reduce the adverse effect induced by vaccination stress of FPV.