Sequence Analysis Of VP2 Hydrophilic Region And Antigenic And Virulent Determining Of Infectious Bursal Disease Virus In HeBei Province

The VP2 variable regions of infectious bursal .disease virus (IBDV) from seven Chinese isolates were amplified by RT-PCR/nested-PCR, and directly sequence. Sequencing and clustering analyses showed that the HeB-bdl, HeB-lf, HeB-qhd, HeB-zjk, HeB-sjz isolates propagated in bursae of SPF chichens were very closely related to very virulent (wIBDV) strain of DV86, UK66K OKYM. They revealed only 1-3 amino acid changes, which suggested that they might have the same origin. On the basis of their distinct geographic originates, extensive dissemination of vvIBDV in Hebei province was indicated. The other one adapted to mild virulent strains HeB-bdx, HeB-cz, HeB-hs, HeB-cd, HeB-bdjz, HeB-hd, HeB-bdv, HeB-xt was grouped with mild virulent strains of Cul and ^2. Pylogenesis of mild virulent strains HeB-bdx, HeB-cz, HeB-hs, HeB-cd, HeB-bdjz and HeB-hd each other is 100%.Strains of different areas in Hebei showed crossed infection, mild virulent strains HeB-bdx, HeB-cz, HeB-hs, HeB-cd, HeB-bdjz and HeB-hd was all the same with SD(qd), HeNn, V-SD, V-MB, V-BJ around Hebei province. wIBDV HeB-bdl, HeB-lf was grouped with BJ-1. All the isolates were distinct from American variants, although variant strains had been reported in China and Hebei province. Regions and amino acids, which were characterized as important for antigenicity or pathogenicity of IBDV, were also discussed.ORFA-l of the larger segment(segment A) encodes 110-kD precursor protein, which can be processed into three mature viral proteins, VP2, VP4, and VP3. With vvIBDV and variant strains showed, it is very important to research of antigen and virulence of IBDV. A few years latter the research showed, VP2 hydrophilic region and antigen variant and virulence of IBDV had very affinity. In order to lucubrate difference of virulence and antigen, and validate correntness of sequencing result, the test adopted Sandwich enzyme-liked immunosorbent assay (ELISA) and antigen caprure-ELISA to determine virulence and antigen. And validate correntness of above-mentioned result. The result showed VP2 hydrophilic region and antigen variant and virulence of IBDV had very affinity. Such is base to research function of VP2 gene in the future.