3株TT病毒的基因组结构特点及其在肝炎病人中感染情况

Genomic structural characteristics of TT viruses isolated from China and their prevalence in patients with different types of viral hepatitis

目的 了解TT病毒 (TTV)分离株基因组结构特点及其在各型病毒性肝炎患者中感染情况。方法 对49株TTV相关病毒全基因组结构进行分子进化树分析 ,比较从我国分离的 3株TTV全基因结构与原型株的同源性 ,并采用巢式聚合酶链反应法 (nPCR)对各型病毒性肝炎患者血清中TTVDNA进行检测。结果 3株TTV分离株基因组全长为 3 73 9bp ,有 2个读码框架 (ORFs) ,ORF1编码 770个氨基酸 ,位于 5 89～ 2 90 1核苷酸 ;ORF2编码 2 0 2个氨基酸 ,位于 10 7～ 715核苷酸。与TTV原型株TA2 78的核苷酸同源性为 86%～ 96% ,ORF1氨基酸同源性为88%～ 97% ,ORF2氨基酸同源性为 79%～ 96%。全基因组序列分子进化树分析表明 ,从我国分离的 3株TTV属于原型组。在 180例各型病毒性肝炎患者中 ,检出TTVDNA阳性 40例 ,阳性率为 2 2 2 %。在甲～戊型肝炎、非甲、戊型肝炎、慢性乙型肝炎患者和正常人中 ,TTVDNA流行率分别为 2 4 2 % ( 2 9/12 0 ) ,18 3 % ( 11/60 ) ,17 8% ( 10 6/5 95 )和 19 8% ( 19/96) ,4组无显著性差异。结论 从我国分离的 3株TTV的全基因结构特点与原型株相似 ,各型病毒性肝炎。

Objective To investigate the genomic structural characteristics of TT viruses isolated from China and their prevalence in patients with different types of viral hepatits.Methods The phylogenetic tree analysis of complete sequence of 49 TTV-related viruses to compare the genomic structural characteristics of 3 Chinese TTV isolated with TTV prototype strain(TA278) and other TTV-related viruses.The nested polymerase chain reaction (nPCR) was used for detection of TTV DNA in sera of patients with different types of viral hepatitis.Results The complete genome of 3 Chinese TTV isolated comprised of 3739 nucleotides with two open reading frames(ORFs).The ORF1 was located at 589-2901nt,encoding 770 amino acids,and the ORF2 at 107-715nt,encoding 202 amino acids.5' and 3' terminals of the genome were non-coding regions including 106?bp and 838?bp,respectively.The nucleotide homology between the 3 Chinese isolated and TTV prototype strain(TA278) was 86%-96% in the complete nucleotides,88%-97% and 79%-96% in ORF1 and ORF2 at the amino acid level,respectively.Phylogenetic tree analysis showed that 3 Chinese TTV isolated could be considered as a member of TTV prototype group.Of 180 patients with different types of viral hepatitis,40(22.2%) were TTV DNA positive.The TTV DNA prevalence rates were 24.2%(29/120),18.3%(11/60),17.8%(106/595),19.8%(19/96) in patients with hepatitis A to E,non-A to E hepatits,chronic hepatitis B and normal population.There were no differences between these four groups.Conclusion Genomic structural characteristics of 3 Chinese TTV isolated were simlar to that of the TTV prototype strain(TA278).The TTV DNA prevalence rates of patients with different types of viral hepatits,chronic hepatitis B and normal population were relatively high.