犬2型腺病毒毒株纤突蛋白基因的比较分析

Comparative Analysis of the CAV-2 Fiber Protein Gene

根据 Gen Bank中犬腺病毒 (canine adenovirus,CAV)纤突基因序列 ,设计合成 2对引物。用 PCR方法 ,对犬 2型腺病毒沈阳分离株 (CAV- 2 SY株 )第 5代强毒 (SY- V5 )、经蚀斑克隆驯化的第 6 0代毒弱毒 (SY- V6 0 )、SY- V6 0在易感犬体上传 5代的回收毒 (SY- CP5 )、美国疫苗毒 (U S- V2 0 )等 4个毒株的纤突基因进行了扩增 ,PCR产物经纯化后进行基因序列测定 ,测序结果经拼接后得到了 1个由 16 2 9个核苷酸组成的纤突蛋白全基因序列 ,编码 5 43个氨基酸。犬2型腺病毒与 Gen Bank中的标准的 CAV- 2强毒株 (Toronto A2 6 / 6 1)纤突蛋白基因序列的比较结果表明 :CAV- 2 SY株强毒株与 Toronto A2 6 / 6 1株相同 ;SY- V6 0株与 SY- CP5相同 ;与驯化前的 SY- V5相比 ,在 1134位发生碱基颠换 ,编码的氨基酸由原来的天冬酰氨 (N)变为赖氨酸 (K) ,并导致 N- X- S/ T潜在糖基化位点发生改变 ,US- V2 0该部位也发生同样的突变 ,本试验测定和比较的 CAV- 2强毒株有 5个潜在的 N-联糖基化位点 ,弱毒株仅有 4个位点 ;U S- V2 0与 Toronto A2 6 / 6 1差异较大 ,有 11个碱基发生变化 ,导致 8个氨基酸的变异。

The canine adenovirus-2(CAV-2) is associated with upper respiratory infection and intestinal syndroms.Adenovirus fiber protein(Fip) plays a crucial role in infection by attaching the virus to a specific cell-surface receptor.I n order to further explain the mechanism of difference in cell tropism and virul ence at molecular level,we designed 2 pairs of primers according to the publishe d CAV-2 Fip gene to amplify the Fip genes with PCR method.The Fip genes of the CAV-2 virulent strain SY-V5,attenuated SY-V60,SY-CP5(derived from SY-V60 pa ssed in susceptible dogs for 5 passages) and USA vaccine strain(US-V20) had bee n sequenced and compared with one another and with that of the standard CAV-2 T oronto virulent strain.Complete Fip gene of all CAV-2 strains were 1 629 nt and 542 amino acids.The deduced amino acid sequences of the Fip of the CAV-2 s trains were compared one another and with that of Toronto strain.Comparing with SY-V5 and Toronto strains,there are point mutation(transversion) occurring in S Y-V60 and SY-CP5 which changes the potential site for asparagine-linked glyco sylation.