| 摘要: | TT病毒（TTV）為1997年由一位不明原因之輸血後肝炎患者的血清中發現之新的單股環狀DNA病毒，由於其基因體序列的變異性極高，因此可以區分為許多種基因型。本研究主要的目的是探討台灣本土TT病毒在肝病病患中感染的盛行率、分離出本土型的病毒株、作基因體定序以及與已發表的病毒株做比較。本實驗首先收集80位各種不同型式的肝炎病人之血液檢體（因為TT病毒時常伴隨著其它肝炎病毒的感染），並利用兩組專一性引子以PCR方法來篩檢是否有TT病毒感染的存在。病人的血清也做了一系列肝功能檢測，以便於分析不同層次的肝炎疾病與TT病毒感染的相關性。此外我們也收集了106位健康的正常人當作控制對照組。從流行病學研究顯示，TT病毒在肝病患者（包括急性肝炎、慢性肝炎、慢性活動性肝炎、B型肝炎帶原者--健康、脂肪肝、肝硬化併發肝癌和原因不明的肝炎）的感染盛行率為33.8%，比健康者17.9%高（p<0.05），然而在上述不同臨床表現的肝炎病患中，其對TT病毒的感染率並沒有顯著差異，ALT值的異常似乎不影響對TT病毒的感染。利用PCR及基因重組技術我們選殖出近95%的TT病毒基因體。經由核酸序列比對的結果顯示本實驗所選殖出來之TT病毒DNA與基因型1a有98%的相似度。
TT virus (TTV) is a newly discovered single-stranded circular DNA virus that was found in serum of a patient with posttransfusion hepatitis of unknown etiology in 1997. TTVs consist of many genotypes and variants, such as TTV 1a, 1b, 2a, 2b …etc. The goal of this study was to investigate the prevalence of the TTV infection in Taiwanese with liver diseases, to isolate the local strain, and sequence the virus genome, and to compare the virus genome with published strain. The study was started by collecting blood samples from patients with a variety type of hepatitis, with the reason that TTV frequently co-infects with hepatitis viruses. For this, 80 blood samples were collected from hepatitis patients for screening the presence of TTV with two sets of polymerase chain reaction (PCR) primers specific for the virus. The serum samples were also quantified for the amounts of alanine aminotransferase (ALT), aspartate amino- transferase (AST), α-fetal protein (AFP), HBsAg and Anti-HCV, so that allowed us to evaluate the correlation between disease progression and TTV-infection. We also collected 106 blood samples from health individual as a control group. From the molecular epidemiological comparison, the prevalent rate of TTV infection was 33.8% in patients with liver diseases (including acute hepatitis, chronic hepatitis, chronic active hepatitis, cirrhosis combined with hepatocellular carcinoma LC/HCC, hepatitis B carrier, fatty liver, and hepatitis with unknown etiology) which was higher than the control group (17.9%, p<0.05). However, no significant clinical manifestation was observed to be associated with TTV infection, and TTV infection did not co-relate to abnormal ALT levels. We also used PCR and recombination DNA technology to clone 95% of TTV genome and compared the nucleotide sequence with the published strains. From the sequence comparison, the similarity of the isolated TTV genomic fragments and TTV-1a strain were 98% . |
