| In this study, IBV S1and IBV M gene were inserted into a eukaryotic expression vector, pVAX, to construct two new plasmids by a flexible linker which could express the (G4S)3polypeptide. The resulting plamsids were designated as pVAX-IBV S1-linker-M and pVAX-IBV M, respectively. Immunofluorescence assays verified the expression of both genes in vitro. The experimental chicken were divided into6groups:the M group inoculated with the pVAX-IBV M, the SIM group inoculated with the p VAX-IBV S1-linker-M,, the virus control group with IBV-Beaudette, the PBS group inoculated with PBS and the YM group with the IBV vaccines and the pVAX group with empty pVAX vetor. Lymphocyte proliferative assay, enzyme linkered immunosorbent assay, neutralization antibody and flow cytometric technique were used to detect the immune response of different groups at different days post-immunization. Finally chickens in different treatment groups were challenged with IBV to compare the difference of the protection rate of the plasmids.The results showed that most of immune response of four inoculated groups was higher than the control group, the pVAX group and the PBS group. The SIM group had the most significant positive effect.It could induce cellular immunity and humoral immunity earlier than the M gene alone. The results showed that the bivalent DNA vaccine (PVAX-S1-linker-M) had a protective effect against the IBV. The histopathological change of IBV target organs of each group were analyzed after challenge and the immunoprotection rates were compared. The results proved that the pVAX-IBV S1-linker-M could enhance the immunoprotection of the host to resist the virus infection.All in all, the results of this experiment showed that combined IBV S and M gene could improve the host immune response and protection rate against the IBV chanllenge. This study providedimportant theoretical basis to the dicovery of new type immune-enhancing vaccine against IBV... |
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