| Infectious Bronchitis (IB) is one of major respiratory infectious diseases of chickens and cause great economic losses to poultry industry. S1 protein is one of the main immune proteins. Although the vaccines made by traditional methods have played important roles in control of infectious diseases, new generation of vaccines, which are safer and can be easily differentiated from wild-type viruses are now in urgent needed. With these advantages, fowlpox virus has been used as a vector to generate a variety of recombinant vaccines, and some of them have already been commercialized. But the distance of immunity between traditional vaccines and recombination vaccines is existed. So it is especially important to enhance the efficiency of recombination fowlpox virus to resist the threatening of different pathogens in poultry industry.The importance of IFNs in innate resistance is not only owing to their antiviral activity, but also to their ability to regulate the functions of cells of innate and adaptive immunity. It is synthesized and excreted by T lymphocyte activated by antigen or mitogen. IFN- can boost the expression of MHC in APC, and so magnify humour immune and cell immune. It can not only be used together with gene vaccine to enhance immunity, but also be used singly to prevent diseases. In this study, a transfer vector containing Chicken Type II Interferon gene and another transfer vector containing Chicken Type II Interferon gene and IBV S1 gene separately primed with LP2EP2 promoter was constructed. The vectors were then used to transfect S-FPV-017 infected CEF cells, and two recombinants (designated as rFPV-IFN and rFPV-IFN-S1) were obtained by identifying blue coloration of plagues and purified through several passages of single plaque. PCR amplification showed that both Chicken Type II gene and S1 gene were in the genome of rFPV-IFN-II-S1. Expression of S1 gene was identified by Western blotting, and also expression of Chicken Type and S1 protein were detected by indirect immuno-fluorescence test.Immune potency of rFPV-IFN-II-S 1 and rFPV-IFN-II was tested on SPF chickens. 112 four-week-old SPF chickens were divided into seven groups averagely and inoculated rFPV-IFN-II S-FPV-017 rFPV-IFN-IB abate vaccine rFPV-IFN-II-S1 rFPV-IBVS1 IB abate vaccine, and control respectively. Antibody detection showed that although rFPV-IFN-II-S1 induced lower antibody level than rFPV-IBVS1 and IB abate vaccine did, but immune potency better than those two after IBV changed. Virus isolation and PCR resultsshowed that groups inoculated rFPV-IFN-IB abate vaccine and rFPV-IFN-S1 were negative at eighth day; groups inoculated rFPV-IBVS1, rFPV-IFN- and IB abate vaccine were negative at tenth day; but control groups were negative at twelve day. Pathological slices indicated that the effect of rFPV-IFN-S1 corresponded to commercial IB abate vaccine, groups inoculated them had light Pathology; groups inoculated rFPV-IFN-II and rFPV-IBVS1 had some Pathology; but control groups had severe Pathology and continued a long time. Weight supervised results showed that inoculation of rFPV-IFN-II, rFPV-IFN-II+IB abate vaccine and rFPV-IFN-II-S 1 had no effect on weight, there had no difference between groups inoculated them respectively and control group. Taking all results together, rFPV-IFN-II-S 1 not only could protected SPF chickens against lethal challenge by virulent IBV but also regulate cellular immune response, it shows feasibility for developing recombinant fowlpox virus gene vaccine in near future, and offeres a new way to control occur and prevalence of IBV.
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