Development of DNA vaccine for infectious bursal disease

• Main Authors: Lei Chi Kei, 李志旗
• Other Authors: C. L. Wu
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/07011659620835895523

碩士 === 國立成功大學 === 生物化學研究所 === 90 === Abstract Infectious bursal disease (IBD) is a serious disease in chickens. The pathogen of the disease is infectious bursal disease virus (IBDV). When chickens are infected by IBDV, immature B-lymphocytes in the bursa of Fabricius undergo apoptosis, which result in immunosuppression. The prevention of IBD is vaccination. In this study, a DNA vaccine based on the VP2 protein was used to immunize chickens against IBD. The viral protein VP2 can produce neutralizing antibody. The VP2 cDNA was subcloned into pTCY, an eukaryotic expression vector, to generate pTCY-VP2 driven by the rat beta-actin promoter as a vector for vaccination. Chickens immunized with VP2 DNA vaccine induced anti-IBDV antibodies, including low-titer neutralizing antibody. However, these chickens died when challenged with virulent IBDV, indicating that the immunization scheme should be modified. In the results from the experiments involving the expression of VP2-EGFP in chicken embryo fibroblasts or in E. coli, we found two interesting phenomena. First there was different localization of EGFP in cells when N-terminally fused with different fragments of VP2. The green fluorescence was localized exclusively in the cytoplasm in cells transfected with pTCY-VP2-EGFP-hl, whereas the fluorescence distributed in both the cytoplasm and nucleus in cells transfected with pTCY-VP2-EGFP-fl or EGFP. The reason for discrepancy in the localization of different EGFP fusion protein is unclear. Secondly, we found that there was a ribosomal binding site at the 5’ end of the EGFP gene and a GTG codon which many serve as a translational intiation site. These sequences may interfere the translation of the VP2-EGFP fusion protein, which resulted in the difficulty in producing VP2-EGFP fusion protein.