传染性法氏囊病超强毒Gx株VP3基因在病毒致弱过程中的变异研究

利用SPF鸡胚对鸡传染性法氏囊病超强毒vvIBDV Gx株进行培育，通过鸡胚成纤维细胞对病毒进行传代致弱，对其结构蛋白VP3基因核苷酸及推导的氨基酸序列进行分析，从而揭示vvIBDV Gx从超强毒力向弱毒力转化过程中基因的序列变化规律。对不同代次细胞毒序列分析的结果表明，细胞毒在第8代以前，VP3基因序列没有改变，与标准超强毒HK46株氨基酸同源性达99％以上；细胞毒第9代核苷酸和氨基酸序列发生了改变；10代毒VP3基因与标准弱毒P2株氨基酸序列同源性达100％；细胞适应毒传至20代，其VP3基因序列不再改变。从而说明，vvIBDV Gx株在致弱过程中，VP3基因也随之改变。

The variation of vvIBDV Gx strain VP3 gene during the process of attenuation

Very virulent infectious bursal disease virus (vvIBDV) Gx strain was cultured in SPF embryo ,attenuated through in CEF successfully. We analyzed the change pattern of VP3 nucleotide and the deduced amino acid sequences. Therefore,we discover the rule of change for vvIBDV Gx from very virulent to attenuate during the process of attenuation.The results of sequencing , analyzing of every generation viruses showed that there was no any changes on VP3 gene before the 8th generation, the homology of amino acid sequence with reference vvIBDV HK46 strain was up to 99 %;there was a few changes in VP3 gene at the 9th generation . The 10th generation has been cell-adapted strain, the homology of amino acid sequence with reference IBDV attenuated strain P2 was up to 100 %. VP3 gene did not change any more from 10th to 20th generation. So,we have drawn conclusion that there exist rule of variation for VP3 of vvIBDV Gx during the process of attenuation.