Analysis And Expression Of Distinctive Epitopes Of The Glycoproteins Of Newcastle Disease Virus Ⅶ Group

Newcastle Disease Virus(NDV) is grouped under the family of Paramyxoviridae, it causes serious infectious disease and incurred great losses to poultry industry. F and HN protein were main glycoproteins, which affect the virulence of the virus. In recent years, the NDV strains isolated in our country mainly belong to group VII, and it was found that sometimes traditional ND vaccine can't offer solid protection to ND caused by isolates in China. Epitope is the mini-unit to induce immune response. Identify the epitopes on NDV will laid solid foundation for development of the ND epitope-vaccine.F gene comparison of NDV isolates in China showed that NDV isolates in China are mainly belong to branches of group based on the phylogenetic tree made by the 1-374 nucleotide of F gene. NDV isolates in group shared 91.7%-99. 7% in homology. In all isolates in our lab, NDV strain GX-2-98 shares homology above 95% with other strain. So the NDV isolates GX-2-98 was chosen to study epitopes.The F and HN segment of the isolates GX-2-98 was amplified, and HN segment of the isolated strain SHX-3-99, HLJ-4-95, QH-2-84, GX-5-97 were amplified. Phylogenic tree from 29 strains were draw based on the NDV HN gene (part segment), and the result is similar to that of F gene.Epitpoes in F and HN gene was analyzed by Dnasis, there are 11 B-cell epitopes and 8 T-cell epitopes in F gene and there is 5 B-cell epitopes and 2T-cell epitopes on the first 165 amino acid of isolated strain GX-2-98. While there are some difference in amino acid with other group(except TW 95), the amino acid in 65-75 of HN of NDV group are conserved, while He in 81 is conserved.Based on epitope prediction, five pairs primers are designed with enzyme sites. Five segments of F1, F2, F3, F4 and HN1 coding epitope was amplified and cloned to prokaryotic expression vector, respectively. The constructed vector was identified by sequencing. After induction by IPTG, four polypeptides coding epitope expressed, respectively. Research in this dissertation laid foundation for the development of ND-epitope-vaccine.