| Summary: | 碩士 === 國立中興大學 === 微生物暨公共衛生學研究所 === 103 === Infectious bursal disease virus (IBDV) causing infectious bursal disease (IBD), a contagious and immunosuppressive disease of young chickens, is one of the most economically significant viruses of poultry worldwide. The major neutralization epitopes of IBDV is located on the viral structure protein VP2. Live attenuated vaccine was usually used to control IBD. However, it causes side-effects such as moderate to severe bursal lesions. The young chickens on farms are protected against IBD by maternal antibody for the first couple weeks post hatch. The objective of this study is to investigate the efficacy of a subunit vaccine containing VP2 protein in chickens with maternal antibody through different vaccination programs. The recombinant VP2 protein was expressed by E. coli and confirmed by western blot. The recombinant protein mixed with Freund’s adjuvant (FA) or ISA 71 as subunit vaccines were used for four animal trials. Enzyme-linked immunosorbent assay (ELISA) titers and virus neutralization (VN) titers of anti-IBDV antibodies were measured for collected chicken sera. All chickens were challenged at 28 days of age and observed for 5 days, and bursal gross lesion scores (BGLS) and bursal histopathological lesion scores (BHLS) were given to each chicken. Protections were evaluated according to the mortality, BGLS and BHLS. The results of animal Trial I and II indicated that the subunit vaccine mixed with ISA 71 and delivered by subcutaneous (SC) route was able to provide 100 % of protection against IBDV challenge in SPF chickens. The results of animal Trial III and IV indicated that the subunit vaccine mixed with ISA 71 and delivered by SC route twice at 7 (or 10) and 18 days of age provided 100 % protection against IBDV challenge in chickens with maternal antibody. In conclusion, the subunit vaccine containing IBDV VP2 protein protected chickens with maternal antibody against vvIBDV challenge.
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