IBDV DNA Vaccine Preparation And Preliminary Study On The Immune Effect

Infectious bursal disease (IBD) is an acute and contagious viral infection of young chickens and turkeys caused by IBD virus (IBDV).Vaccination is the most effective way to prevent the disease. Furthermore,live attenuated vaccines have the potential to revert back into a virulent phenotype. Inactivated vaccines are typically safe, but are less effective than attenuated vaccines.Therefore, there is a demand for new effective vaccines to prevent IBDV infection. DNA vaccination, the delivery of plasmid DNA encoding immunogens by direct inoculation, offers the potential for further advancements in the production of effective vaccines.VP2 protein is the the major structural protein of IBDV and considered to be major host protective antigens.In this study,pcDNA3.1(+)cloning vector was used as a expression vector for IBDV-VP2 protein.VP2 gene of IBDV (strain HuBei) was amplified with gene-specific primers, designed by the PRIMER 5.0 software, and cloned between Nheâ… and Hindâ…¢restriction enzyme sites in multiple cloning site (MCS) A pcDNA3.1(+)of expression vector that formed pc-VP2.HEK-293 cells in 6-well tissueculture plates were transfected with the constructed plasmid mediated,which was performed as described in the instruction manual. Expression of the encoded proteins of the plasmid pc-VP2 in HEK-293 cells was revealed by IFA.Fourteen-day-old chickens were randomly separated into 7 groups,10 each group, free foraging and drinking water, and conducted for vaccination trials.Blood samples were collected from the wing vein of each chicken once a week before challenge and. Serum antibody titres to the expressed IBDV protein from the constructed plasmid were determined by ELISA. The relative level of antibody was represented as the optical density value at the wavelength of 450 nm. Anticoagulated blood samples were also collected once a week before challenge,the cell multiplication of peripheral blood lymphocyte were detected.The results showed that serum antibody titres of chickens in different immunity groups were significantly higher than control group. Lymphocyte,group G(commercial attenuated IBD live vaccine)got a great propagation at 7 days after immunization. In the vaccination experiments, chickens that received the plasmid VP2 DNA and chemical adjuvant were better protected than chickens (control groups).Protection rate of pc-VP2 groups were 70%,as the same as the group G(commercial attenuated IBD live vaccine).All test results show that the pc-VP2 plasmid DNA vaccine provides a new thinking of preventing IBD.