一株TT病毒中国分离株结构区全基因的克隆及序列测定

目的 克隆和序列测定ＴＴ病毒（ＴＴＶ）中国分离株全国基因。方法 采用长片段ＰＣＲ技术从一例临床非甲－非庚型肝炎病人血清中扩增ＴＴＶ全基因，获得３个互相重叠的片段，分别为１９９、３２６９和４３４ｂｐ。用标准分离子生物学方法测定这３个片段的序列，从而得到全长ＴＴＶ基因序列。结果 ＴＴＶ中国分离株全基因长３７３９个核苷酸，含两个开放读码框架。第一个ＯＲＦ位于５８９至２９０１位核苷酸，编码７７０个氨基酸；

Cloning and sequencing of a Chines ecomplete TTV gene

OBJECTIVE: To obtain the complete TT virus gene from a Chinese isolate. METHODS: Long-PCR was performed for amplifying the TTV gene from the serum of a Chinese with non-A to non-G hepatitis. Three overlapped DNA fragments were obtained, which contained 199 bp (1-199), 3 269 bp (38 approximately 3 306) and 434 bp (3 306 approximately 3 739) separately. These PCR products were sequenced by the standard method. RESULTS: The complete TTV gene (named as TTV CHN1) consisting of 3 739 nucleotides contained two ORFs. The first ORF located at 589 approximately 2 901 nt, coding 770 amino acids; the second located at 107 approximately 715 nt, coding 202 amino acids. In this genome, G is 22.25%, C 25.54%, A 31.26% and T 20.97%. The homology of Chinese and Japanese TTV genes was more than 94% at both nucleotide and amino acid levels. There exists a hyper-variation region (HVR) spanning at 1 380 approximately 1 800 bp. In this region, the HVR homology of Chinese and Japanese TTV genes was 88% and 81% at nucleotide and amino acid levels, respectively. CONCLUSION: Chinese and Japanese TTV isolates belong to the same genotype. There exists a hyper-variation region (HVR) spanning at 1 380 approximately 1 800 bp.