Distribution of TT virus genomic groups 1-5 in Brazilian blood donors, HBV carriers, and HIV-1-infected patients

Human isolates of the highly prevalent TT virus (TTV) have been classified into five major genomic groups (1-5). The geographical distribution of the groups throughout the world is not well known. Five different PCR assays were developed in an attempt to amplify specifically TTV DNAs of each genomic group. Serum samples collected from 72 Brazilian adults (24 voluntary blood donors, 24 hepatitis B virus (HBV) carriers, and 24 human immunodeficiency virus type 1 (HIV-1)-infected patients) were tested. TTV DNA from at least one genomic group was detected in 11 (46%) blood donors, 13 (54%) HBV carriers, and 24 (100%) HIV-1 patients. All five genomic groups were detected in the three populations, with the exception of group 2 in blood donors. Some samples, negative with all five specific assays, were positive with the commonly used untranslated region (UTR) PCR system. On the other hand, TTV DNA was detected in some samples by using specific assays but not with the UTR PCR. Mixed infections with 2-5 TTV isolates from different groups were detected in 21% blood donors, 29% HBV carriers, and 71% HIV-1 patients. Fifteen PCR products (three obtained with each assay) were sequenced. Most sequences showed high (>86%) homology with those of TTV isolates belonging to their presumed groups. However, three sequences had low homology with all TTV sequences available from the DNA databanks. In conclusion, TTV isolates belonging to all five known genomic groups circulate in Brazil, and the results suggest the existence of new and as yet uncharacterised major genomic groups.     

昆明地区TTV感染的临床流行病学监测

目的 了解昆明地区输血传播病毒(Transfusion Transnfited Virus,TTV)感染的流行情况。方法 对本科77例住院人的血清用聚合酶链反应(PCR)法进行TTV检测。结果 检出11例TTV阳性患。结论 昆明地区肝病病人中存在TTV感染,感染率低于国内外水平。感染途径包括非肠道途径和肠道途径。     

非甲至非戊型肝炎患者TTV检测和部分基因序列分析

目的：研究新近报道的一种与输血后肝炎有关的病毒在中国郑州地区正常人群、HBsAg阳性者、非甲至非戊型肝炎患者中的感染和基因序列变异情况。方法：采用TTV基因组ORF1区的套式聚合酶链反应(nested-PCR)方法对血清标本进行检测,并对非甲至非戊型肝炎患者中的TTV分离株进行序列测定。结果：TTV DNA在非甲至非戊型肝炎患者中检出率为45％(18／40);在正常体检者中检出率为17．7％(17／96);在HBsAg阳性者(ALT≤34 IU／L)中检出率22．7％(10／44)。TTV分离株序列与日本株(CLON22)相对应位置的核苷酸同源性为．1％。结论：TTV在非甲至非戊型肝炎患者TTV的感染率明显高于其他人群,可能是非甲至非戊型肝炎的主要致病因子。     

血清TTV-DNA检测及TTV肝炎临床特点初探

目的：了解输血传播病毒（ＴＴＶ）在非甲～庚型肝炎中的感染状况,探讨其在肝炎发病中的作用和地位。方法：采用套式ＰＣＲ法检测血标本中的ＴＴＶ－ＤＮＡ。结果：检测了３０例非甲～庚型肝炎病人,其中血清ＴＴＶ－ＤＮＡ阳性者１１例,阳性率３６．７％。结论：ＴＴＶ感染与ＡＬＴ异常有极为密切的关系,可能是导致非甲～庚型肝炎重要病原。     

输血传播病毒（TTV）感染的研究

目的: 了解输血传播病毒 (TTV) 在广西人群中感染情况, 探讨TTV 在肝炎发病中的作用与地位。方法: 用套式聚合酶链反应检测血清中TTVDNA,用ELISA或RT—PCR法排除非甲—庚型肝炎病毒。结果:正常献血员TTVDNA阳性率为16.4% (12/73), HBV感染者TTV DNA阳性率为4.3% (2/46), 显著低于正常献血员(χ2 = 3.97, P< 0.05), 非甲—庚肝炎患者TTV DNA阳性率为35.4% (6/17), 与正常献血员无显著性差异(χ2 = 3.0, P> 0.05), TTV感染在男女性别中无显著性差异, 但在30～50岁人群中感染率(17/78) 显著高于其他年龄段(4/58) (χ2 = 4.92, P< 0.05)。结论: 广西存在TTV 感染,且中年人群高于其他年龄段人群,TTV与HBV可有存在互相抑制或干扰作用, 但TTV可能不致病或具轻微致病性     

深圳地区HBsAg阳性人群TTV核酸序列分析

目的 分析HBsAg阳性和阴性人群输血传播肝炎病毒（TTV）感染率的差异及TTV病毒核酸序列。方法应用套式PCR扩增TTV病毒核酸序列，将扩增的TTV核酸片段进行核酸测序，构建进化树分析TTV核酸序列的同源性。结果 HBsAg阳性和阴性人群TTV感染率比较，差异无统计学意义，深圳TTV病毒株与日本TTV病毒株的核酸序列同源性较大。结论人群中TTV病毒株携带率与HBsAg的携带率无相关性。     

样品不同处理方法对PCR-微孔板杂交法检测TTV DNA的影响

自1997年底日本学者Nishizawa等[1]报道从输血后肝炎病人血清中分离出TTV以来 ,不少学者做了大量有关TTV的检测工作.目前国内外用PCR方法检测TTV的报告较多,但不同实验室检测的结果存在较大差异,可能与其检测方法特别是样品处理方法不同有关.我们比较了8种常规的DNA抽提方法,并建立了适合于PCR-微孔板杂交法检测TTV DNA的标本处理方法.     

TTV Viral Load As a Marker for Immune Reconstitution After Initiation of HAART in HIV-Infected Patients

Abstract

Purpose: To investigate whether TT virus (TTV) viral load may be used as a surrogate marker for functional immune reconstitution in HIV-infected patients receiving highly active antiretroviral therapy (HAART). Method: Fifteen protease inhibitor-naÏve HIV-infected patients were included in a longitudinal study. From each patient, three serum samples taken before HAART initiation and three samples taken during HAART were analyzed. TTV was detected by polymerase chain reaction (PCR) and was quantitated by competitive PCR. TTV viral heterogeneity was determined by restriction fragment length polymorphisms (RFLPs) and sequencing. Results: All 15 HIV-infected patients were TTV positive. No significant change in HIV RNA or TTV viral load was observed at the three time points before HAART initiation. Even though HAART lead to an immediate and significant reduction in HIV RNA (p = .0001), a significant reduction in TTV viral load (p = .0002) was not observed until after 3-5 months of HAART. Four patients did not have an increase in CD4+ T cell count after 1 year of HAART; however, a decrease in TTV viral load was still observed, and three of these patients had a reduction in HIV RNA. RFLPs and sequencing revealed that TTV is represented as a heterogeneous population of virus in HIV-infected patients. Conclusion: This pilot study suggests that HAART leads to improved immunological responses, even in patients who do not have an increase in CD4+ T cell counts. We propose that the change in TTV viral load may be useful in the evaluation of cellular immune response at a functional level in HIV-infected patients who receive HAART.     

武汉地区职业献血员血清TTV等病毒核酸的检测

目的 调查武汉地区既往职业献血员血清TTVV DNA及其他几种肝炎病毒基因的状况与特点。方法采用PCR或巢式PCR对74例既往乡村献血员进行血清TTV DNA及HCV RNA、HGV RNA的检测。结果 TTVDNA、HCV RNA及HGV RNA阳性检出率分别为43.2％、23.0％与2.7％,TTV DNA检出显著高于其他肝炎相关病毒,HCV RNA阳性率显著高于HGV RNA阳性率。结论 既往长期的献血已造成地区乡村职业献血员TTV与HCV感染率的显著升高。