一种新的TTV基因群全基因序列测定及基因结构分析

Sequencing and analysis of genomic structure of two distinct TT virus variants related to a novel genetic group

目的 测定 2株TTV高度变异株全基因序列 ,对其基因结构、基因分型及分子流行病学分析。方法 从 2名感染TTV高度变异株的婴儿血清中抽提其DNA ,用longinvertedPCR扩增出全基因组并测定其序列 ,同时对测序结果进行分析。根据测定的序列设计引物 ,对人群中此类变异株的感染情况进行研究。结果 首次报道了TTV一个新基因群———第 5基因群 ;测定了该基因群中 2株变异株的全基因序列。该基因群在小于 30日龄、1～ 6月龄、7～ 12月龄的婴儿中检出率分别为 0、2 7.3%、39.5 %,献血员中检出率为 45 .8%。结论 虽然第 5基因群基因组核酸序列呈高度异质性 ,但其基本结构及功能与已报道的TTV各基因群十分相似 ;婴儿中该基因群的感染主要与环境因素有关。

Objective Sequencing, analysis of genomic structure of two distinct TT virus (TTV) variants. Methods DNA was extracted from 2 viremic infants in Jiujiang city who were infected with divergent TTV variants unclassifiable into the known four genetic groups. Full-length genome of TTV was then amplified by long inverted PCR and then cloned, sequenced and analyzed. Based on the entire nucleotide sequences of two isolates determined in this study, PCR primers were designed and synthesized for detecting the prevalence of the novel TTV variants among the population. Results A new TTV genetic group, group 5, was identified in the present study; the entire nucleotide sequences of 2 novel TTV variants named CT39F, CT44F were determined. In addition, the prevalence of TTV infection among infants less than 30 days, 1-6 months and 7-12 months of age was 0, 27.3%, 39.5% respectively and in volunteer blood donors living of the same region was 45.8%. Conclusion Results obtained in the present study indicated an extremely genetic diversity among the novel group, genetic group 5 and other four reported groups. However, basic genomic organization and its function were highly conserved. In addition, group 5 TTV was negative among the infants less than 30 days of age and detected at a high frequency of 27.3% and 39.5% at the age of 1-6 months and 7-12 months respectively. This suggested an age-dependent increase of TTV infection in early childhood in this city and the environmental factors are potentially concern with. [