西安地区TTV毒株分子结构特点的初步研究

Pilot study on molecular speciality of TTV genome in Xi'an

目的 :研究西安地区TTV(Transfusiontransmittedvirus)基因组结构是否为环状 ;对西安地区TTVDNA部分序列直接测序分析 ,比较其与中国 1株同源性。方法 :自行在TTV基因组首尾端设计一套环形检测引物 ,检测西安地区肝炎患者TTVDNA阳性血清 ,有无特异性片段。参照文献设计一套套式检测引物 ,内引物扩增片段长为 197bp ,将 197bp处特异性条带从低熔点凝胶中切下 ,纯化后以自带引物直接测序法测序 ,测得的 143bp序列与Genebank注册的BDH1同源性比较。结果 :环形引物套式PCR扩增在 30 0bp处出现特异性条带 ,提示西安地区TTV毒株可能首尾相连。西安地区TTV毒株与BDH1同源性为 6 5 .0 % ,差异率 35 .0 % (>30 % ) ;143bp中的 6 2bp序列与BDH1同源性达 75 .8%。结论 :西安地区TTVDNA结构可能有环形株存在 。

Objective:To study the structure of TTV genome and analyze part of the sequence of TTV in Xi'an.Methods:Two sets of primers complementary with the sequence at 3′ end and 5′end of TTV were synthesized and nested-PCR was perfomed to find if 3′end was connected with 5′end. The other two sets of primers were complementary with ORF1(Open Reading Frame 1) according to Nishizawa,the sequence of the amplified product was 197 bp between two inner primers. A target fragment in the agarose was cut down and the amplified product was purified and sequenced directly, the data was analyzed with DNAsis software in computer.Results:The amplified products were about 300 bp which were longer than the predicted piece of 182 bp. The partial TTV DNA sequence with 143 bp was detected . Compared with complete sequence of BDH1, we found that homology between BDH1 and partial sequence of TTV in Xi'an was 65.0%.Conclusion:These results suggest that the genome of TTV strain in Xi'an may possess a circular structure and the new genotype of TTV may exist in Xi'an.