不同人群TTV检测及阳性标本核苷酸序列分析
Detection of TT virus infection and nucleotide sequence analysis of partial positives samples from different populations
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摘要:目的 了解不同人群TTV感染状况及基因型别, 探讨TTV传播途径。方法 设计合成引物采用半套式聚合酶链反应方法, 对献血者、肝炎病人、幼儿及母婴配对等4组人群血清进行TTVDNA的PCR检测并对部分阳性株进行序列测定及分析。结果 (1) 在457份被检血清中检测出TTVDNA阳性111份, 总阳性率24.29%。在血清转氨酶(ALT)正常的96份献血者血清标本中TTVDNA阳性检出率为16.6%, 而在ALT异常、HBsAg及抗HCV阴性的99份献血者血清标本中, TTVDNA的阳性检出率为36.3%, 明显高于ALT正常献血者。(2)在72例不同肝炎病人血清中, TTVDNA阳性检出率为54.16%;在非甲-庚型肝炎病人中TTVDNA阳性率为875%, 高于甲-庚型肝炎的病人中TTVDNA阳性率。(3)110份体检幼儿血清中, 共检出TTVDNA阳性14份, 总检出率为12.73%。(4)一对母婴配对血清的TTVDNA同时阳性且序列相同。(5)12个阳性株序列分析结果显示: 11株分属于G1、G22个基因型的5个亚型, 而另1株与Gla、Glb的同源性为74.8%~80.2%。结论 (1) 献血者人群中存在TTV感染, TTV可以导致感染个体的肝功能异常。(2)TTV感染与肝炎有关, 可能是非甲-庚型肝炎的病原之一。(3)TTV可能存在血源途径外的其它传播选径; TTV存在母婴垂直传播途径。Abstract:Objective To investigate the prevalence and gene types of TT virus infection in different people (populations).Methods TTV DNA were detected by a hemi-nested polymerase chain reaction (PCR) assay in sera from blood donors, hepatitis patients, children and in sera from mothers and paired cord. Several amplified products were sequenced and the data were analyzed with the computer programs.Results The total detection rate of TTV DNA was 24.29% (111/ 457) in all objects. The positive rate of TTV DNA in various populations were as follows: In donors, 16.6%(16/96)with elevated transaminase level while 36.3%(36/99)with nomal transaminase level and there were significant differences between them. In hepatitis patients, the total detection rate of TTV DNA was 54.16% and the positive rate was 87.5%(7/ 8)in non A-G hepatitis while 50% in patients whose diagnosis were clear. In children, TTV DNA was detected in 14 out of 110(12.73%).TTV DNA was detected in 5 of 40 sera of the mother, and 1 of 40 cord sera of infants was TTV DNA positive while his mother was TTV infected.12 sequences of 222 bp of ORF1 selected form the positive samples were analyzed and compared with sequenced representation of publics isolates which revealed that 11 of them can be classified into 5 subgroups of group G 1 and G2, and another may be a new subgroup of G1.Conclusion Elevation of ALT was associated with TTV infection, which may be one of the cause of non A-G hepatitis. There may be other transmitted routes besides blood-borne. TTV can cross the placenta and mother-to-fetus transmission is an important mean.
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