献血员、肝炎患者TTV DNA检测及部分TTV基因序列分析

目的了解献血员、肝炎患者中的输血传递病毒(TTV)感染状况及基因型别。方法设计合成引物采用半套式聚合酶链反应（hemi-nestPCR）方法，对195份献血员血清、72份不同型别的肝炎患者血清进行了TTVDNA的PCR检测,并对部分阳性株进行序列测定及计算机分析。结果①在血清丙氨酸转氨酶（ALT）异常，HBsAg及抗HCV阴性的99份献血员血清标本中，检出TTVDNA阳性标本36份，阳性检出率为36.3%；而在ALT正常的96份献血员血清标本中，检出TTVDNA阳性标本16份，阳性检出率为16.6%,明显低于ALT异常献血者。②在72例不同肝炎患者中，共检出39例TTVDNA阳性血清，总检出率为54.16%，在非甲-非庚型肝炎患者中TTVDNA阳性率为87.5%，而在明确诊断为甲-庚型肝炎的患者中TTVDNA阳性率为50%，两组相比差异显著（P<0.05）。对8株阳性株序列分析结果显示，测序的8个分离株与9个G1、G2代表株核酸的同源性为60.4%～99.1%，氨基酸的同源性为55.4%～98.6%。经系统发育分析表明，这8个TTV分离株中有7株可分属于G1、G2两个基因型的5个亚型,而另1株为G1型的新亚型。结论①献血者中存在TTV感染，提示TTV可以导致感染个体的肝功能异常，TTV可能与HBV感染相似，亦存在“健康携带状态”。②非甲-非庚型肝炎患者的TTV感染率明显高于明确病原的甲-庚型肝炎患者，TTV感染与肝炎有关，可能是非甲-非庚型肝炎的病原之一。③8个TTV分离株中7个分属于G1、G2两个基因型中的5个亚型,另有1株为G1型的新亚型。

Detection of TT virus DNA and partial sequence analysis in sera from blood donors and hepatitis patients

Objectives:To study the prevalence of TT virus(TTV) genomes in blood donors and hepatitis patients and analyze the partial sequences of TTV isolates phylogenetically. Methods:A hemi nested polymerase chain reaction (PCR) assay was established to detect TTV DNA in sera from donors and hepatitis patients,the PCR amplified product was sequenced and analyzed with computer programs. Results:TTV DNA were positive in 16 (16.6%) out of 96 blood donors with elevated transaminase level and 36 out of 99 ( 36.3 %) with normal transaminase level. The total detection rate of TTV DNA in the 72 subjects was 54.16 %. TTV positive rate was 87.5% in nonA G hepatitis (7 of 8), but 50% in hepatitis patients. Analysis was made to the 8 positive samples with 222bp of ORF1 and compared with the sequenced representative of publics isolates, which reveal that 7 belonged to group G1 and G2. The rest was a new subgroup of G1. Conclusions:Elevation of ALT was associated with TTV infection, which may be one of the cause of non A G hepatitis.