Prevalence and implication of TT virus infection: minimal role in patients with non-A-E hepatitis in Taiwan.

TT virus (TTV) is a newly identified human DNA virus and little is known about its clinical significance. The aim of the study was to explore the prevalence of TTV infection in different risk populations and in patients with various liver diseases. Viral DNA was studied in 190 high-risk individuals, 97 household contacts, 52 patients with acute hepatitis A, 32 patients with non-A-E hepatitis including 13 fulminant hepatitis, 200 asymptomatic hepatitis B surface antigen (HBsAg) carriers, 100 patients with chronic hepatitis C, and 100 healthy adults. TTV infection was more frequent in high-risk groups (26-70%), patients with acute or fulminant non-A-E hepatitis (42-45%), and hepatitis C carriers (36%) than in healthy adults (10%) and hepatitis B carriers (15%). However, most of subjects with TTV infection alone had no or only mild hepatitis, and the same rate of TTV DNA in pre-hepatitis serum samples and constant serum TTV titers during hepatitis episodes were observed in two patients with acute non-A-E hepatitis. Phylogenetic analysis of the Taiwanese TTV isolates showed genetic heterogeneity and most (68%) isolates were TTV type 1. No particular strain was found to be associated with fulminant non-A-E hepatitis.     

Retrospective analysis of non-A-E hepatitis: possible role of hepatitis B and C virus infection

In an effort to determine the cause of non-A-E hepatitis, a retrospective study was undertaken on a group of patients with hepatitis but without serological infection markers of hepatitis viruses A-E. A total of 60 patients admitted to Beijing Ditan Hospital during the period of September 1997 and September 1999 were chosen for this study. These patients were diagnosed as either acute or chronic hepatitis, but no serological markers of hepatitis viruses A-E were detected. Since TT virus (TTV), human parvovirus B19 (B19), SEN virus (SENV), and GB virus C/HGV were reported to be associated with hepatitis, attempts were made to detect the presence of these viruses in the sera of patients with non-A-E hepatitis by a nested polymerase chain reaction (nPCR) method. Also, more sensitive nPCR and RT-nPCR methods were used to determine HBV DNA and HCV RNA in these patients. Results derived from these analyses demonstrate that HBV DNA was detected in most of these patients (47/60, 78.3%), suggesting that HBV infection played a major role in occult non-A-E hepatitis and detection of HBV DNA by more sensitive PCR methods such as nPCR should be considered for diagnosis of HBV infection. In addition, HCV RNA was detected in three (5%) of these patients. However, GBV-C (HGV) RNA was not detected, and TTV, B19, and SENV appear not to be associated with non-A-E hepatitis, as the prevalence rates of these viruses in patients with non-A-E hepatitis were similar to those in patients with viral hepatitis A-E. The results from this study indicate that co-infection of TTV or B19 with HBV did not increase the severity of the disease.     

Detection of hepatitis G virus RNA in patients with hepatitis B,hepatitis C,and non-A-E hepatitis by RT-PCR using multiple primer sets

Hepatitis G virus(HGV)/GB virus C(GBV-C) is a newly identified virus associated with human hepatitis. The preliminary prevalence studies of HGV infection in Japan were entirely based on the detection of HGV RNA by RT-PCR. However, the selection of the different primer sets in such assay may influence sensitivity of the test because of the extensive genetic heterogeneity of HGV, and influence the estimation of the prevalence of HGV. To address this potential problem, we designed two primer sets from well conserved domains in the 5′NC and NS5 regions of HGV genome, and tested them together with the NS3-derived primer set in RT-PCR for their ability to detect HGV RNA in serial dilution of synthetic viral RNA templates. Subsequently, we used these three primer sets to detect HGV RNA in the sera of 371 Japanese patients with hepatitis B, hepatitis C, and non-A-E hepatitis. The results indicated that the primer set derived from the 5′NC region appeared to be most effective in detecting HGV RNA. The results also showed that only two out of the 126 patients (1.6%) with non-A-E hepatitis were positive for HGV RNA although the RNA were detected more frequently in patients with hepatitis B (2/38; 5.3%) and hepatitis C (17/207; 8.2%), suggesting that HGV is not a common causative agent for non-A-E hepatitis in Japan. J. Med. Virol. 52:385–390, 1997. © 1997 Wiley-Liss, Inc.     

Prevalence of TTV DNA among children with a history of transfusion or liver disease

The prevalence rates of serum TT virus (TTV) DNA among children with or without a history of transfusion or liver disease were studied by polymerase chain reaction (PCR) using either the Okamoto primer set or the Takahashi primer set developed more recently. Using Okamoto and Takahashi primer sets, the prevalence rates were 31.6% (12/38) and 78.9% (30/38), respectively, for children with a history of blood transfusion (including malignant and non-malignant groups) and 6.7% (2/30) and 60% (18/30), respectively, for children without a history of blood transfusion. Among pregnant women, these rates were 12.9% (4/31) and 61.3% (19/31), respectively. On the other hand, the prevalence rates were 0% (0/16) and 50% (8/16), respectively, in hepatitis B patients, 21.4% (3/14) and 71.4% (10/14), respectively, for hepatitis C patients, and 20.0% (9/45) and 57.8% (26/45), respectively, for non-A to C hepatitis patients (including 27 acute hepatitis patients, 5 fulminant patients and 13 chronic hepatitis patients). In this study, the prevalence rates determined by the Takahashi primer set tended to be 2-9 times higher than those determined using the Okamoto primer set. These results suggest that TTV infection is widespread among Japanese children. Furthermore, blood transfusion does not appear to be the major route of infection. The similar prevalence rates between control children and children with various types of hepatitis using the Takahashi primer system suggest that TTV infection does not play a direct causative role in the development of liver disease in children.     

Occurrence of a novel DNA virus (TTV) infection in patients with liver diseases and its frequency in blood donors.

A novel DNA virus (TTV) was identified recently in Japanese patients with posttransfusion hepatitis non-A-E and has been implicated as a cause of acute and chronic liver diseases of unknown etiology in some patients. The frequency of TTV infections was investigated in 284 blood donors, 105 patients with different liver disorders before and after liver transplantation (OLT), as well as in 64 patients with chronic hepatitis C who received antiviral therapy. TTV infections were found more frequently by nested-PCR in patients with liver disorders (15%) as compared to blood donors (7%). TTV occurred independently of the aetiology of the liver disease (e.g., cryptogenic cirrhosis [12.5%], alcoholic cirrhosis [16%], fulminant hepatic failure non-A-E [35%], and chronic hepatitis C [12.5%]; p=n.s.). After OLT, a high rate of TTV de novo infections (44%) was observed. However, TTV viremia after OLT (in 56 out of the 105 patients) was not associated with graft hepatitis. Analysis of patients with chronic hepatitis C coinfected with TTV who have been treated with interferon alpha alone or in combination with ribavirin revealed that TTV is an interferon-sensitive virus. Phylogenetic analysis of TTV sequences suggest that at least four different genotypes and several subtypes exist in Germany. In conclusion, the high prevalence of TTV infections observed in patients with parenteral risk factors is an argument in favour of transmission of the virus via blood and blood products. A relevant hepatitis-inducing capacity of TTV, however, seems unlikely, considering the observation that in the majority of patients, TTV infection after OLT was not accompanied by graft hepatitis.     

分子杂交法研究肝炎病人血清和肝组织中输血传播病毒

目的 对各型肝炎病人血清和肝组织中输血传播病毒（TTV）核酸检测分析,探讨病毒的致病性。方法 以地高辛为标记物制备TTV DNA探针,斑点杂交法、原位杂交法分别检测血清中及肝组织中TTV DNA。结果 检测103例血清,TTV总阳性率为25．24％（26／103）;甲－戊型肝炎组检出率21．81％（12／55）、非甲－非庚型患者检出率47．37％（9／19）,显著高于正常对照组15％（3／20）。临床可见TTV的单独感染和重叠感染;出现急性、慢性甚至重度肝损伤。12 肝组织可见TTV阳性,阳性颗粒主要见于肝细胞核内。结论 从血清和肝组织证实了TTV的存在,提示这种病毒可能是导致肝脏炎症的一种新病原。     

Etiology of sporadic acute viral hepatitis in Taiwan: the role of hepatitis C virus, hepatitis E virus and GB virus-C/hepatitis G virus in an endemic area of hepatitis A and B.

The etiology of sporadic acute hepatitis was studied in 334 consecutive patients from Taiwan (237 men and 97 women, aged 16-81 years), with emphasis on the role of hepatitis C virus (HCV), hepatitis E virus (HEV), and GB virus-C/hepatitis G virus (GBV-C/HGV) in acute non-A, non-B (NANB) hepatitis and in HBsAg carriers with superimposed acute hepatitis. According to the conventional diagnostic criteria, there were 12 cases (3.6%) of acute hepatitis A, 17 cases (5.1%) of acute hepatitis B, 128 cases (38.3%) of acute NANB hepatitis, and 177 cases (53.0%) of acute hepatitis in HBsAg carriers (those who were HBsAg positive but IgM anti-HBc negative). Among 128 cases of acute NANB hepatitis, 70 (54.7%) had acute hepatitis C (HCV RNA positive), 5 (3.9%) had acute hepatitis E (IgM anti-HEV positive), and the other 53 (41.4%) were presumably acute hepatitis non-A-E. The prevalence of acute hepatitis A, B, E, and non-A-E showed no significant sex difference, whereas acute hepatitis C was significantly more prevalent in females. The prevalence of acute hepatitis A and B decreased and that of acute hepatitis C increased significantly with increasing age. In contrast, acute hepatitis E and non-A-E showed no significant age predominance. Of 177 HBsAg carriers with acute hepatitis, 64 (36.1%) demonstrated non-B hepatotropic virus superinfection, with HCV being the most common (60.9%), followed by hepatitis D, E, and A viruses, and the other 55 (31.1%) and 58 (32.8%) were presumed to have acute exacerbation of chronic hepatitis B or superimposed acute hepatitis non-A-E, respectively. Serum GBV-C/HGV RNA was detected in 3-4% of acute hepatitis non-A-E cases, suggesting its limited role in these cases.     

Prevalence and risk factor analysis of TTV infection in prostitutes

TTV, a DNA virus, has been isolated from patients with non-A to non-E post-transfusion hepatitis. In the past it was assumed that TTV was transmitted parenterally. It is unclear whether sexual contact leads to transmission of this virus. In this study, two sets of TTV-specific polymerase chain reaction primers were used to detect serum TTV DNA in 140 prostitutes and 136 controls. The prevalence of TTV DNA in prostitutes was significantly higher than in the control group (46/140 [32.9%] vs. 29/136 [21.3%]; P = 0.043). There was no significant difference in the prevalence of positive antibody to hepatitis A virus (anti-HAV) in either group (87.8% for prostitutes, 85.3% for controls). No particular risk factor was significantly associated with positive TTV DNA in prostitutes. In summary, TTV is highly prevalent in prostitutes. Transmission of TTV via sexual contact is not as efficient as transmission of hepatitis C and D viruses and GB virus-C hepatitis G virus. The high prevalence of TTV in controls indicates that there are diverse routes of transmission of this virus.     

TT virus levels in the plasma of infected individuals with different hepatic and extrahepatic pathology

TT virus (TTV) infection is extremely widespread in the general population. A sensitive real-time PCR assay was developed that quantitated accurately the most prevalent TTV genotypes in Italy. When used to test 217 individuals for TTV viraemia, the overall prevalence was 94%. Viraemia levels varied widely amongst individual subjects, with no major differences related to gender or age. The highest TTV titres were in haemophiliacs and in patients with non-A-E hepatitis, but they did not differ from the group with miscellaneous diseases. HIV- and HCV-infected subjects and patients with primary liver diseases had TTV loads similar to those of healthy individuals.     

TTV在肝炎患者中的检测及临床意义探讨

目的研究新近报道与丙氨酸转氨酶异常相关的ＴＴＶ在已知和未知病毒性肝炎中的临床意义。方法设计ＴＴＶ部分基因的特异性引物，用聚合酶链反应（ＰＣＲ）方法检测了１０４例病毒性肝炎的ＴＴＶＤＮＡ，并对１例ＴＴＶ阳性标本克隆测序。结果ＴＴＶＤＮＡ序列与日本ＴＴＶ部分基因序列相对应位置的核苷酸同源性为９８．４％。在１０４例肝炎患者中ＴＴＶＤＮＡ阳性检出率为２４．０％（２５／１０４），其中在非甲～戊和庚型肝炎患者中为４８．０％（１２／４２），在甲型肝炎中为１９．０％（４／２１），乙型肝炎为２５．０％（８／３２），丙型肝炎为１１．１％（１／９），９例ＨＧＶＲＮＡ阳性者中未检出ＴＴＶＤＮＡ。值得注意的是重型肝炎ＴＴＶ检出率极高，其中急性重型肝炎６例中阳性为４例（６６．７％），慢性重型肝炎６例中阳性为３例（５０．０％）。结论ＴＴＶ在我国肝炎病人中存在。在重型肝炎中有较高的发生率，可能是未知病毒致急性和慢性及重型肝炎的病因之一。     

Prevalence of TT virus infection in Italian dialysis patients

OBJECTIVE: A novel DNA virus, transfusion-transmitted virus (TTV) is identified from the serum of a patient from acute hepatitis non-A-E. Few reports have been published on patients with renal disease. Patients on dialysis were at high risk of blood-borne viral infections and little is known about the prevalence of this virus in dialysis patients. In order to verify the prevalence of infection from TTV in these patients, we have examined the incidence of TTV in Italian patients with dialysis. METHODS: Serum samples of 85 patients and 65 healthy individuals were examined. In order to evidence the presence of the TTV virus, a method of the seminested polymerase chain reaction (PCR) with TTV-specific primers derives from the N22 region deIl'ORF-1 of the virus has been used and products were analyzed by agarose-gel electrophoresis. All serum samples were also analyzed to markers HBV and HCV. RESULTS: The prevalence of TTV DNA in dialysis patients [35/85 (41.7%)] was significantly higher than in healthy population [7/65 (10.7%)]. Among TTV positive dialysis patients, HCV coinfection was present in six cases. The positivity rate for TTV-DNA tends to increase with age. CONCLUSION: Transfusion-transmitted virus had a high prevalence in Italian-dialysis patients. In our study the virus did not have an important clinical effect on patients; but remains the possibility that it may aggravate liver disease caused by HCV. However, the question of whether TTV infection might have a possible effect on dialysis patients requires further investigation in larger groups.     

Effect of interferon on a nonenveloped DNA virus (TT virus) associated with acute and chronic hepatitis of unknown etiology.

An unenveloped DNA virus named TT virus (TTV) has been reported in association with acute and chronic hepatitis of unknown etiology. The effect of interferon on TTV was evaluated in the patients with chronic hepatitis C who were coinfected with TTV. TTV DNA was determined by a polymerase chain reaction with heminested primers in the 96 patients with chronic hepatitis C who received interferon-alpha (516 million units in 26 weeks) and followed for 24 months thereafter. TTV DNA was detected in 31 (32%) patients before therapy. TTV DNA became undetectable during interferon therapy and remained absent in 14 (45% of the 31 patients) through 24 months thereafter. The four patients with pretreatment TTV DNA titer > or =10(3)/ml did not respond. These results indicate that TTV is sensitive to interferon, and the response would be inversely correlated with pretreatment viral titers.     

原位杂交法检测非甲～庚型肝炎患者肝组织中TT病毒DNA

目的 证实在非甲－庚型病毒性肝炎患者肝组织中TT病毒（transfusion-transmitted virus,TTV)的存在。方法 采用地高辛素标记TTV DNA探针以原位杂交技术对51例血清学病毒标记非甲－戊型、免疫组化检测肝组织中HBsAg、HCV NS3Ag及HGV N55Aag阴性的病毒性肝炎患者石蜡包埋肝组织进行了检测。结果 各型病毒性肝炎肝组织中TTV基因的总检出率为27．5％,其中急性轻型肝炎的检出率为30．8％（4 ／13）,急性重型肝炎为1／8,亚急性重型肝炎为3／7,慢性肝炎为2／6,活动性肝硬化为2／9,慢性重肝肝炎为1／4,原发性肝癌为1／4。TTV DNA表达于肝细胞核或胞质内,以核型多见。在急性肝炎,TTV阳性细胞弥漫分布于肝小叶内,慢性肝炎于汇管区附近较为密集,而在肝硬化病例,阳性细胞在假小叶内多呈片族状不规则分布。结论 在不明原因病毒性肝炎患者血清及肝组织中TTV DNA的检出表明TTV为一种新型的肝炎病毒,TTV为一种嗜肝性病毒。     

GB virus C/hepatitis G virus and TT virus infections among high risk renal transplant recipients in India.

BACKGROUND: GB virus C/hepatitis G virus (GBV-C/HGV) and TT virus (TTV) have been widely reported in patients with high parenteral risk such as haemodialysis and renal transplant recipients. The occurrence of these agents in association with hepatitis B virus (HBV) and hepatitis C virus (HCV), in Indian renal transplant recipients, is yet unreported. STUDY DESIGN: Molecular and serological markers of GBV-C/HGV and TTV were examined in addition to those for HBV, HCV and hepatitis D virus (HDV) in a selected group of seventy renal transplant recipients. HGV RNA detection was achieved using primers specific for the 5'NCR and NS5a regions of the genome. Anti-GBV-C/HGV antibody was detected using the mu plate anti-HG env kit (Roche, Germany). TTV DNA PCR was performed using primers specific for the coding region (method A) of the genome. In 50% of patients, TTV DNA was also tested for using primers specific for the non-coding region (method B). Host related factors such as age, alanine aminotransferase (ALT) levels, number of transfusions, haemodialysis sessions, and months following transplantation were also studied. RESULTS: Exposure rates to GBV-C/HGV, TTV (method A), HBV, HCV and HDV were 58.6, 32.9, 52.9, 54.3 and 2.9%, respectively. 'Active' infection as measured by viraemia and/or virus-specific antigenaemia for GBV-C/HGV, TTV, HBV and HCV was 52.9, 32.9, 15.7 and 52.9%, respectively. The majority of GBV-C/HGV and TTV infections were seen as co-infections with other hepatitis viruses. Single infection with GBV-C/HGV and TTV was seen in ten (14.2%) and eight (11.4%) patients, and was not associated with ALT elevation when compared to uninfected blood donors. Using univariate analysis, GBV-C/HGV RNA was significantly associated with > or =20 haemodialysis sessions. TTV DNA occurrence was not associated with any risk factors. CONCLUSIONS: There is a high occurrence of GBV-C/HGV and TTV in this select group of renal transplant recipients in India. These viruses mostly occurred in the context of co-infections with other hepatitis viruses. Long term effects of multiple hepatotropic viral infections need to be carefully documented in such transplant populations.     

High prevalence of TT virus infection in Brazilian blood donors

A recent report has described the molecular cloning and characterization of a novel, single-stranded DNA virus, named TT virus (TTV), which was present in the sera of Japanese patients with posttransfusion hepatitis of unknown etiology [Okamoto et al. (1998) Hepatology Research 10:1-16]. Using a nested polymerase chain reaction assay, sera from Brazilian patients with acute non A-C hepatitis and blood donors were examined for the presence of TTV DNA sequences. Thirty-seven of 52 (71%) patients with acute non A-C hepatitis and 45 of 72 (62%) blood donors were found to have TTV sequences in their sera. Such a high proportion in blood donors indicated that TTV infection is common in the general Brazilian population. Partial nucleotide sequences (326 bases in open reading frame 1) from seven isolates were determined. By phylogenetic analysis, four TTV strains were classified into the genomic subgroup G1a described previously. The three others belonged to subgroup G1b. Sequence homologies between strains belonging to a same subgroup were 92.9-99.1%, whereas homologies of 85.9-90.2% were calculated between isolates from different subgroups.     

Prevalence of TT Virus and GBV-C Infections among Patients with Liver Diseases and the General Population in Shanghai,China

To determine the prevalence of TT virus (TTV) and GB virus C/hepatitis G virus (GBV-C) infections among patients with liver disease and the general population in Shanghai, China, we studied 90 patients with liver diseases (acute hepatitis, 28; chronic hepatitis, 27; liver cirrhosis, 20; hepatocellular carcinoma, 15) and 90 age, sex matched healthy blood donors as controls. There were no significant differences in the clinical and demographic characteristics between the two groups, except for liver function test values. There was a statistical difference between the patient group and the control group with regard to the prevalence of TTV DNA (23.5% in patient group, 11.1% in control group, P<0.05), although no differences in clinical features could be found between TTV DNA-positive and negative subjects. Also, no differences in TTV DNA prevalence among various categories of liver diseases were noted (P = NS). The prevalence of HBsAg was significantly different between the patient group (36.7%) and the control group (3.3%) (P<0.01), whereas the prevalence of anti-HCV and GBV-C RNA were not significantly different between the two groups. The nucleotide sequences were determined in the TTV DNA-positive samples and evaluated using phylogenetic analysis which suggested that they could be divided into two main genotypes designated as genotype 1 and 2. There were five samples clustered into 3 hitherto unknown subtypes of genotype 2. We concluded that (1) although TTV infection is widespread among both groups and there is a statistical difference of TTV infection between them, no hepatic damaging evidence and correlation with certain liver disease could be found in this study, suggest that TTV may not be major cause of liver disease, (2) GBV-C infection is frequent, but the virus is not the cause of liver diseases, and (3) new subtypes of TTV may exist in Shanghai, China.     

TTV酶联免疫方法的建立及其初步应用

目的 建立检测TTV的酶免疫技术,了解不同型肝炎患者血清中抗－TTV抗体的分布情况,并结合TTV DNA的检测分析两者的关系。方法 以原核表达的TTV ORF1蛋白为抗原建立检测抗－TTV的酶联免疫吸附试验（ELISA）方法,采用该方法检测不同肝炎患者中抗－TTV抗体;在套式聚合酶链反应（PCR）方法检测血清标本中TTV DNA。结果 所建立的检测TTV的ELISA方法具有较好的特异性,不同别肝炎患者中抗－TTV抗体阳性率分别为：甲型肝炎患者10.5%（4／38）,乙型肝炎患者12.5%（16／128）,丙型肝炎患者8.3%(7/84),丁型肝炎患者7.7%(30/93),健康人群1.3%(1/78)。统计学分析表明,非甲－庚型肝炎患者抗－TTV阳性率显著高于其他型肝炎患者（P＜0.01）,而正常人群则显著低于肝炎患者（P＜0.05）。抗－TTV阳性率与TTV DNA阳性率存在相关性（P＜0.05）。结论 在不同型肝炎患者中均可检出抗-TTV抗体,但以非甲－庚型肝炎患者阳性率高;TTV抗体可与基因同时存在于患者血清中,抗－TTV抗体可能类似抗－HCV, 是一传染性标志。     

TT病毒在谷丙转氨酶升高的体检者和肝病患者中检 …

目的 通过研究ＴＴ病毒在谷丙转氨酶升高的体检人群和肝病患者中的意义。探讨其致病性。方法 收集１９例谷丙转氨酶升高体验者和４１例转氨酶正常的随机对照的血清,以及１８２例肝病患者的血清,采用ＰＣＲ方法检测ＴＴ病毒的ＤＮＡ。聚合酶链反应（ＰＣＲ）产物经限制性片段长度多态性（ＲＦＬＰ）分析验证。同时检测甲,乙,丙,戊,庚型肝炎病毒（ＨＡＶ,ＨＢＶ,ＨＣＶ和ＨＧＶ）感染标志。结果 １９例转氨酶升高体检者中,