TT viral infection through blood transfusion: retrospective investigation on patients in a prospective study of post-transfusion hepatitis

AIM To investigate the role of blood transfusion in TT viral infection (TTV).METHODS We retrospectively studied serum samples from 192 transfusion recipients who underwent cardiovascular surgery and blood transfusion between July 1991 and June 1992. All patients had a follow-up every other week for at least 6 months after transfusion. Eighty recipients recipents blood before screening donors for hepatitis C antibody (anti-HCV), and 112 recipients reveiver screened blood.Recipients with alanine aminotransferase level ＞ 2.5 times the upper normal limit were tested for serological markers for viral hepatitis A, B,C, G, Epstein-Barr virus and cytomegalovirus.TTV infection was defined by the positivity for serum TTV DNA using the polymerase chain reaction method. RESULTS Eleven and three patients, who reveiver anti-HCV unscreened and screened blood, respectively, had serum ALT levels ＞90 IU/L. Five patients (HCV and TTV: 1; HCV,HGV, and TTV: 1; TTV: 2; and CMV and TTV: 1 )were positive for TTV DNA, and four of them had sero-conversion of TTV DNA. CONCLUSION TTV can be transmitted via blood transfusion. Two recipients infected by TTV alone may be associated with the hepatitis.However, whether TTV was the causal agent remains unsettled, and further studies are necessary to define the role of TTV infection in chronic hepatitis.     

TT virus and hepatitis G virus infections in Korean blood donors and patients with chronic liver disease

AIM: To determine the prevalences of TTV and HGV infections among blood donors and patients with chronic liver disease in Korea, to investigate the association of TTV and HGV infections with blood transfusion, and to assess the correlation between TTV and HGV viremia and hepatic damage. METHODS: A total of 391 serum samples were examined in this study. Samples were obtained from healthy blood donors (n=110), hepatitis B surface antigen (HBsAg)-positive donors (n=112), anti-hepatitis C virus (anti-HCV)-positive donors (n=69), patients with type B chronic liver disease (n=81), and patients with type C chronic liver disease (n=19). TTV DNA was detected using the hemi-nested PCR. HGV RNA was tested using RT-PCR. A history of blood transfusion and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were also determined. RESULTS: TTV DNA was detected in 8.2 % of healthy blood donors, 16.1 % of HBsAg-positive donors, 20.3 % of anti-HCV-positive donors, 21.0 % of patients with type B chronic liver disease, and 21.1 % of patients with type C chronic liver disease. HGV RNA was detected in 1.8 % of healthy blood donors, 1.8 % of HBsAg-positive donors, 17.4 % of anti-HCV-positive donors, 13.6 % of patients with type B chronic liver disease, and 10.5 % of patients with type C chronic liver disease. The prevalence of TTV and HGV infections in HBV- or HCV-positive donors and patients was significantly higher than in healthy blood donors (P<0.05), except for the detection rate of HGV in HBsAg-positive donors which was the same as for healthy donors. There was a history of transfusion in 66.7 % of TTV DNA-positive patients and 76.9 % of HGV RNA-positive patients (P<0.05). No significant increase in serum ALT and AST was detected in the TTV- or HGV-positive donors and patients. CONCLUSION: TTV and HGV infections are more frequently found in donors and patients infected with HBV or HCV than in healthy blood donors. However, there is no significant association between TTV or HGV infections and liver injury.     

A prospective study of transfusion-transmitted virus transmission by blood transfusion

Recently, a new single-stranded DNA virus (TT virus, TTV) has been isolated and related to post-transfusion hepatitis. The aim of this study was to investigate the prevalence of TTV in blood donors and blood recipients, and the incidence of TTV transmission by blood transfusion. TTV DNA and serum markers of hepatitis B virus (HBV) and hepatitis C virus (HCV), were examined in 130 blood recipients, and the presence of TTV was studied in their 340 corresponding blood donors. The prevalence of TTV infection was 10.6% (36/340) in donors and 8.5% (11/130) in blood recipients, before transfusion. Eighteen subjects (15.1%) were found to be TTV positive, after transfusion, in the 119 blood recipients without TTV before transfusion; at least one of the corresponding donors was TTV positive. There were 46 subjects with post-transfusion hepatitis virus infection, 45 with HCV infection (including seven co-infected with TTV) and two with HBV infection (including one co-infected with HCV and one co-infected with TTV). The recipient with TTV and HBV co-infection and three of the seven patients with TTV and HCV infection had alanine aminotransferase (ALT) levels higher than 90Ul^–1, but only two of the 10 isolated TTV infections had a mild ALT elevation. These results show that prevalence of TTV was high in blood donors and hospitalized patients, and isolated TTV infection is not related to significant ALT elevation.     

TT virus infection in hemodialysis patients

OBJECTIVE: Recently, TT virus (TTV), associated with posttransfusion hepatitis, was discovered. Prevalence of TTV infection in maintenance hemodialysis (HD) units and its pathogenicity to liver was investigated. METHODS: A total of 115 patients on HD were assessed for presence of serum TTV. DNA was purified from sera, and nested polymerase chain reaction was done for the detection of TTV DNA. RESULTS: TTV was detected in 59 patients on HD (51.3%), as compared with healthy blood donors (15 of 91 [16.5%], p < 0.0001). Serum HCV RNA and HBs antigen were positive in 16 and three patients, respectively. The prevalence rate of TTV was already 58.3% in the patients on HD for only 1 yr, and did not change according to the duration of HD until 15 yr on HD. TTV was positive in 51.2% (43 of 84) of the patients with history of blood transfusion, and in 51.6% (16 of 31) of those without it. In HCV-negative patients, alanine aminotransferase (ALT) levels of TTV-positive patients were similar to those of TTV-negative patients. Contrarily, in HCV-positive patients, ALT levels were more frequently > or =15 IU/L in TTV-positive patients (14 of 18) than in TTV-negative patients (five of 15) (p < 0.05). CONCLUSIONS: TTV infection is remarkably prevalent in patients on HD and in healthy blood donors. It is suggested that TTV generally does not cause liver disease by itself, but there remains the possibility that TTV may aggravate liver disease caused by HCV.     

Transmission of and liver injury by TT virus in patients on maintenance hemodialysis

To study the prevalence and clinical significance of TT virus (TTV) infection in hemodialysis patients, we tested for TTV DNA in serum, using the nested polymerase chain reaction. The prevalence of TTV DNA in 352 hemodialysis patients was 32%, significantly higher than that in 50 healthy blood donors (12%). The prevalence increased with age (P = 0.0098); it was 20% (22/110) in patients aged less than 49 years, 37% (69/188) in those aged 50–69 years, and 41% (22/54) in those aged over 70 years. Other clinical features and the prevalence of other hepatitis viral markers tested did not differ between patients with TTV DNA and those without it. The detection rate of hepatitis C virus (HCV) and hepatitis G virus (HGV) viremias increased with duration of hemodialysis and with the number of blood transfusion units, but the prevalence of TTV viremia did not. Twenty-nine of 91 patients followed for 5 years were initially positive for TTV DNA. Of these 29 patients, 17 (59%) carried this viremia for at least 5 years. Fourteen of the 62 patients (23%) who were initially negative for TTV DNA acquired TTV viremia. Serum alanine aminotransferase (ALT) levels were elevated in patients with HCV viremia but not in patients with HGV or TTV viremia. However, the mean ALT level in patients with all three viremias (HCV, HGV, and TTV) was significantly higher than that in patients with one or two of the viremias. More than 30% of the hemodialysis patients had TTV viremia and the carrier state was maintained for years. The hemodialysis procedures, including blood transfusion, did not seem to be crucial for the transmission of TTV. The pathogenic effects of TTV on hepatitis appear to be limited. (Received July 21, 1998; accepted Sept. 25, 1998)     

输血传播性病毒的流行病学及临床研究

目的:观察分析不同人群中TTV(transfusion transmitted virus)感染状况及相关临床意义。方法:在TTVORF1设计引物,建立巢式聚合酶链反应,检测不同人群中血清TTV DNA,并对比观察肝炎病人的临床表现。结果:29例健康人群,27例职业献血员,56例乙型肝炎,31例丙型肝炎和47例非甲～非庚型肝炎患者中,TTV DNA阳性率分别为6.9％、3.7％、23.2％、25.8％和42.6％。3种肝炎病人中,TTV DNA阳性和阴性组间4项主要临床指标无显著差异。结论:健康人群和职业献血员存在TTV健康携带者。非甲～非庚型肝炎患者TTV感染率最高。乙型和丙型肝炎患者重叠TTV感染较常见。3种肝炎病人中,合并TTV感染组与非感染组临床表现无明显差异。TTV的致病性尚待深入研究。     

TT virus infection in Thailand: prevalence in blood donors and patients with aplastic anemia

Aplastic anemia has been reported to occur after viral hepatitis of unknown etiology. Recently, TT virus (TTV), a novel DNA virus, was identified in a Japanese patient with posttransfusion non-A-E hepatitis. The prevalence of TTV infection was investigated among blood donors and patients with aplastic anemia in Thailand. Of 99 blood samples from blood donors, 37 tested positive for TTV DNA via semi-nested polymerase chain reaction (PCR) using TTV-specific primers. Seventeen percent of samples from blood donors younger than 20 were positive for TTV DNA, whereas 48% from donors older than 20 were positive. The high prevalence of TTV infection in Thailand is comparable to that reported in China (28%), Mongolia (43%), and Egypt (29%). Forty-two percent of newly diagnosed aplastic anemia patients tested also had TTV DNA in blood. The detection rate of TTV DNA in aplastic anemia patients does not differ significantly from rates in normal blood donors. Our present data thus argue against the role of this novel hepatitis-associated virus in the pathogenesis of aplastic anemia in Thailand. However, larger epidemiological studies may be needed to further evaluate their association.     

Transfusion-associated TT virus infection and its relationship to liver disease.

TT virus (TTV) has been proposed as the causative agent of non-A to E hepatitis. We studied the association between TTV viremia and biochemical evidence of hepatitis in blood donors and prospectively-followed patients. TTV was found in 7.5% of 402 donors and in 11.0% of 347 patients before transfusion. The rate of new TTV infections was 4.7% in 127 nontransfused, and 26.4% in 182 transfused patients (P <.0001). The risk of infection increased with the number of units transfused (P <.0001). The rate of new TTV infections in 13 patients with non-A to E hepatitis (23.2%) was almost identical to the rate in 124 patients who were transfused, but did not develop hepatitis (21.8%). Of 45 patients with acute hepatitis C, 40.0% were simultaneously infected with TTV. TTV did not worsen the biochemical severity (mean ALT: 537 in TTV+; 550 in TTV-) or persistence of hepatitis C. In non-A to E cases, the mean ALT was 182 in those TTV-positive and 302 in TTV-negatives. No consistent relationship between alanine transaminase level and TTV DNA level was observed in 4 patients with long-term, sequential samples. Of 21 viremic subjects, 67% cleared TTV within 5 years (38% in 1 year); 33% were viremic throughout follow-up extending to 22 years. We conclude that TTV is a very common, often persistent infection that is transmitted by transfusion and by undefined nosocomial routes. We found no association between TTV and non-A to E hepatitis and no effect of TTV on the severity or duration of coexistent hepatitis C. TTV may not be a primary hepatitis virus.     

A prospective study on TT virus infection in transfusion-dependent patients with beta-thalassemia

A novel DNA virus designated TT virus (TTV) has been reported to be involved in the development of posttransfusion non-A-C hepatitis. We evaluated the frequency and natural course of TTV infection in a cohort of transfusion-dependent thalassemic patients in a 3-year follow-up study. Ninety-three serum hepatitis C virus (HCV) antibody-negative patients (median age of 8 years; range, 0 to 25) from eight centers were studied. Of them, 34 (37%) had an abnormal alanine-aminotransferase (ALT) baseline pattern, and the other 12 (13%) showed ALT flare-ups during the follow-up. TTV DNA in patient sera collected at the time of enrollment and at the end of follow-up was determined by polymerase chain reaction (PCR). In parallel, serum samples from 100 healthy blood donors were also tested. At baseline, 87 patient sera (93.5%) tested positive for the TTV DNA. Of these TTV DNA-positive patients, 84 (96.5%) remained viremic at the end of the study period. Of the 6 TTV DNA-negative patients, 3 acquired TTV infection during follow-up. However, no definite relation was observed between the results of TTV DNA determination and ALT patterns. TTV viremia was also detectable in 22% of blood donors. In conclusion, TTV infection is frequent and persistent among Italian transfusion-dependent patients. The high rate of viremia observed in healthy donors indicates that the parenteral route is not the only mode of TTV spread.     

High rate of TTV infection in multitransfused patients with pediatric malignancy and hematological disorders

The prevalence of transfusion-transmitted virus (TTV) infection has not been known in patients suffering from pediatric malignancies and hematological disorders who receive blood transfusion and/or blood products during treatment. Blood samples were taken from 75 patients. TTV infection was identified when TTV DNA was detected in serum by a polymerase chain reaction (PCR) assay. Hepatitis C virus (HCV) and hepatitis G virus (HGV) RNA were also assayed by PCR. TTV DNA was detected in 38 of 75 patients (51%). In 4 of 38 patients, the amount of blood transfused was less than 3 units. By time since last transfusion, TTV DNA was detected in 12 of 35 patients after more than 4 years, 12 of 21 between 1 and 4 years, and 14 of 19 within 1 year. Six patients had mixed infection of TTV and HCV, and 12 patients had mixed infection of TTV and HGV. Three different kinds of virus were found simultaneously in serum from 3 patients. Eight out of 75 patients showed abnormal levels of alanine aminotransferase (ALT) (>40 IU/liter), and 3 of them had TTV DNA. All patients who had TTV DNA and elevated ALT levels also were positive for HCV RNA and HGV RNA. The prevalence of TTV infection is high in patients with pediatric malignancies and hematological disorders after episodes of blood transfusion. Transfusion is one of the most important risk factors for TTV infection regardless of the amount of blood transfused.     

Prevalence of TT viral DNA in italian blood donors with and without elevated serum ALT levels: molecular characterization of viral DNA isolates

BACKGROUND AND OBJECTIVE: A novel non-enveloped DNA virus, called TT virus (TTV), has been reported to be associated with post-transfusion hepatitis of unknown etiology. Although its clinical role still remains obscure, its presence in blood donations might cause problems. It, therefore, appeared of interest to investigate TTV prevalence in voluntary blood donors. DESIGN AND METHODS: A total of 595 Italian blood donors with and without elevated serum alanine aminotransferase (ALT) levels were tested by polymerase chain reaction using two sets of semi-nested primers that amplify the well-known region in the N22 clone. The amplified products were then sequenced to assess the genotype by phylogenetic and restriction fragment length polymorphism analyses. RESULTS: The prevalence of TTV in blood donors was 5+/-1.9% (25 out of 500) with a 95% confidence limit. A similar prevalence was found in 95 selected blood donors with increased ALT levels. A viral load of 10(3)-10(4) viral DNA molecules/mL was found, thus indicating a rather narrow range of variability. A phylogenetic tree built up on the basis of 210 base sequences of ORF1 allowed isolates to be classified into 2 groups corresponding, at least, to two of the putatives TTV genotypes, group 1 and group 2 of Okamoto's classification. A similar classification was also obtained by site restriction enzyme analysis. INTERPRETATION AND CONCLUSIONS: The results show that TTV infection is present among Italian blood donors. No significant difference in prevalence of TTV infection was found between patients with normal and increased ALT, making the association between TTV infection and human hepatitis questionable.     

Transfusion transmissible virus TTV and its putative role in the etiology of liver disease

TTV, the transfusion transmissible hepatitis virus infects mainly patients at risk for parenteral exposure and hence, prone to develop chronic liver disease, as well as healthy populations worldwide. Most TTV infections appear to occur parenterally, with viremia detected frequently in blood donors and blood products. The substantial proportion of asymptomatic individuals never exposed to blood-borne agents, and its high prevalence among healthy subjects implicates the fecal-oral route as another potential for transmission. According to the TTV DNA levels detected in liver tissue, it apparently replicates in hepatocytes, and TTV DNA is present in sera of patients with posttransfusion hepatitis of unknown etiology closely correlated with ALT levels. However, TTV initiating the development of chronic liver disease or causing posttransfusion hepatitis could not be confirmed, as most patients positive for TTV DNA remain asymptomatic and those progressing towards chronic liver disease are invariably coinfected with either the hepatitis B or C virus. Also, TTV coinfection does not aggravate the symptoms associated with hepatitis B or C. Similarly, it does not cause posthepatitis aplastic anemia, and high-risk patients can immunologically clear the viral DNA. In conclusion, being widely distributed and apparently nonpathogenic, TTV might represent an opportunistic but innocent virus reminiscent of hepatitis G virus, with a negligible role in the etiology of chronic liver disease.     

TT virus infection in screened Taiwanese blood donors

OBJECTIVE: TT virus (TTV) is a newly discovered human DNA virus of uncertain clinical significance. The aim of this study was to determine the prevalence of TTV infection among blood donors in Taiwan. METHODS: Viral DNA was studied in 224 healthy blood donors and 118 deferred donors. DNA was extracted from plasma and amplified by seminested polymerase chain reaction with reported primer sets from a conserved region of the TTV genome. RESULTS: The prevalence of TTV DNA in the deferred donors was 24.6%, significantly higher than in the healthy donors (11.9%). TTV was also more prevalent in those with hepatitis B surface antigen than in those without it (p = 0.002). CONCLUSION: In comparing normal with deferred Taiwanese blood donors, hepatitis B virus infection is linked to a higher prevalence of TTV infection.     

健康人群和肝病患者中检测TTV的意义

目的了解新型肝炎病毒－ＴＴＶ的致病性和在健康人群和肝病患者中的流行情况．方法收集１８０份健康体检患者血清和１５６份不同类型肝病患者血清,采用ＰＣＲ方法检测ＴＴＶ的ＤＮＡ．同时检测ＨＡＶ,ＨＢＶ,ＨＣＶ,ＨＥＶ和ＨＧＶ感染标志,比较分析ＴＴＶ在健康人群和不同类型肝病患者中流行情况及其致病性．结果健康体检人群和肝病患者中,ＴＴＶＤＮＡ检出率分别为２２％和４５％,两组间无显著性差异（Ｐ＞００５）．体检人群中,ＡＬＴ正常和升高者的检出率分别为１７％和１４３％．急性肝炎,慢性肝炎和肝硬变者的检出率分别为４８％,４３％和４７％．１１例阳性患者中,３例ＡＬＴ正常,８例ＡＬＴ异常．在８例ＡＬＴ异常患者中,６例为ＨＢＶ现行感染,１例为ＨＣＶ现行感染,仅１例为ＮＡ－Ｇ肝炎患者．结论在中国健康体检人群和肝病患者中能检出低水平的ＴＴＶ现行感染．但似乎仅引起个别患者的转氨酶轻度升高．ＴＴＶ的致病性可能较弱或需要其他因素协同致病．     

High frequencies of HGV and TTV infections in blood donors in Hangzhou

AIM: To determine the frequencies of HGV and TTV infections in blood donors in Hangzhou. METHODS: RT-nested PCR for HGV RNA detection and semi-nested PCR for TTV DNA detection in the sera from 203 blood donors, and nucleotide sequence analysis were performed. RESULTS: Thirty-two (15.8%) and 30 (14.8%) of the 203 serum samples were positive for HGV RNA and TTV DNA, respectively. And 5 (2.5%) of the 203 serum samples were detectable for both HGV RNA and TTV DNA. Homology of the nucleotide sequences of HGV RT-nested PCR products and TTV semi-nested PCR products from 3 serum samples compared with the reported HGV and TTV sequences was 89.36%, 87.94%, 88.65% and 63.51%, 65.77% and 67.12%, respectively. CONCLUSION: The infection rates of HGV and/or TTV in blood donors are relatively high, and to establish HGV and TTV examinations to screen blood donors is needed for transfusion security. The genomic heterogeneity of TTV or HGV is present in the isolates from different areas.     

Lack of association between TTV viral load and aminotransferase levels in patients with hepatitis C or non-B-C

TT virus (TTV) is a newly identified un-enveloped single-stranded DNA virus. Although TTV was initially thought to be a new hepatitis virus, it is still unclear whether it causes hepatitis. To clarify the natural history and pathogenesis of TTV infection, serial serum samples from patients with chronic hepatitis were analysed. TTV DNA was quantified by real-time detection polymerase chain reaction assay (RTD-PCR), which was adapted for TTV. Five patients with chronic hepatitis, 4 with hepatitis C and 1 with non-B-C, were studied. The study period ranged from 9 to 50 months. In 3 patients there were frequent increases in TTV DNA titres, but no concomitant elevation of the aminotransferase (ALT) levels. In 2 patients who were treated with interferon, the changes in TTV titres were not synchronized with those of the ALT levels. Thus, in cases of chronic hepatitis, no correlation was observed between the serum TTV DNA titres and the ALT levels.     

Natural history of the TT virus infection through follow-up of TTV DNA-positive multiple-transfused patients

Little is known about the natural history and the pathogenicity of the TT virus (TTV). We present our findings of a cross-sectional study based on the TTV DNA screening of 173 multiple-transfused patients and a longitudinal study based on the follow-up of TTV DNA-positive patients. Overall, 48 patients (27.7%) tested positive for TTV DNA. The influence of the number of blood donor exposures on the prevalence of blood-borne viral infection indicates that TTV, hepatitis C virus (HCV), and an RNA virus known as GB virus C/hepatitis G virus (GBV-C/HGV) share a parenteral transmission, but that TTV, in contrast to the 2 other viruses, is also transmitted by at least another efficient means. The patients having a well-defined date of TTV infection were positive for TTV DNA during a mean period of 3.1 years. A chronic infection was observed in 31 cases (86%). TTV carriage appeared clinically benign in all patients. No clinical evidence of a disease potentially linked to the TTV infection was observed in patients with TTV DNA carriage over several years. The majority of TTV carriers had no biochemical evidence of liver disease. The prevalence of elevated serum alanine aminotransferase (ALT) level was higher in the TTV DNA-positive group, even in the absence of HCV infection, but the observed peaks of ALT level were most often transient and very mild. The prevalence of TTV DNA observed in blood recipients is consistent with that of TTV infection observed in blood donors. TTV infection frequently tends to persist. (Blood. 2000;95:347-351)     

TT virus in bone marrow transplant recipients

TT virus (TTV) is a newly discovered transfusion-transmissible DNA virus, which may cause posttransfusion hepatitis. The virus was detected in 12% of Japanese blood donors. The aim of the study is to investigate the prevalence and clinical influence of TTV in bone marrow transplant (BMT) recipients. Sera from 25 BMT recipients obtained 6 to 12 weeks after the transplant were examined for TTV-DNA by the seminested polymerase chain reaction. Serial samples were additionally analyzed in patients with TTV-DNA. Fifteen of 25 recipients (60%) were positive for TTV-DNA after transplant, whereas it was detected in only two of 20 BMT donors (10%). In patients positive for TTV-DNA before BMT, the amount of TTV-DNA decreased to an undetectable level during the myelosuppressed period after BMT. We also found that there was a novel group of TTV, G3, classified by the nucleotide sequences. The median peak alanine aminotransferase (ALT) levels were 135.0 IU/L and 116.5 IU/L (normal range, 4 to 36 IU/L) in TTV-positive and TTV-negative recipients, respectively. In one of the seven TTV-positive patients who developed hepatic injury (ALT > 150 IU/L), a serial change in the serum TTV titer showed a good correlation with the ALT level. We concluded that (1) the prevalence of TTV is high in BMT recipients, (2) TTV might be replicated mainly in hematopoietic cells, (3) transfusion-transmitted TTV may cause persistent infection, (4) a novel genetic group of TTV, G3, was discovered, and (5) TTV does not seem to frequently cause hepatic injury, although one patient was strongly suggested to have TTV-induced hepatitis.     

Transfusion-transmitted virus in association with hepatitis A-E viral infections in various forms of liver diseases in India

AIM: To describe the prevalence of transfusion-transmitted virus (TTV) infection in association with hepatitis A-E viral infections in different forms of liver diseases in North India. METHODS: Sera from a total number of 137 patients, including 37 patients with acute viral hepatitis (AVH), 37 patients with chronic viral hepatitis (CVH), 31 patients with cirrhosis of liver and 32 patients with fulminant hepatic failure (FHF), were analyzed both for TTV-DNA and hepatitis A-E viral markers. Presence of hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis E virus (HEV) infections was detected in different proportions in different groups. Moreover, TTV-DNA was simultaneously tested in 100 healthy blood donors also. RESULTS: None of the patients had hepatitis A virus (HAV) and hepatitis D virus (HDV) infections. Overall prevalence of TTV-DNA was detected in 27.1% cases with AVH, 18.9% cases with CVH, 48.4% cases with cirrhosis and 9.4% cases with FHF. TTV-DNA simultaneously tested in 100 healthy blood donors showed 27% positivity. On establishing a relation between TTV infection with other hepatitis viral infections, TTV demonstrated co-infection with HBV, HCV and HEV in these disease groups. Correlation of TTV with ALT level in sera did not demonstrate high ALT level in TTV-infected patients, suggesting that TTV does not cause severe liver damage. CONCLUSION: TTV infection is prevalent both in patients and healthy individuals in India. However, it does not have any significant correlation with other hepatitis viral infections, nor does it produce an evidence of severe liver damage in patients with liver diseases.     

The epidemiology of TT virus (TTV) infection in a hepatitis C and B virus hyperendemic area of southern Taiwan

TT virus (TTV) is a newly isolated DNA virus from the serum of a patient with posttransfusion hepatitis of unknown etiology in 1997. To evaluate the clinical and molecular characteristics of TT virus (TTV) in a hepatitis C virus (HCV) and B (HBV) hyperendemic area (Masago), 200 residents were enrolled in the study. The sera were tested for alanine aminotransferase (ALT), HCV RNA and GB virus C/Hepatitis G virus (HGV) RNA, TTV DNA, HBsAg, anti-HCV and antibodies to HGV E2-protein (anti-E2). TTV DNA was positive in 99 of the 200 sera with a prevalence rate of 49.5%. The prevalence of HBsAg, anti-HCV, HCV RNA, HGV RNA, anti-E2 and HGV exposure (defined as positive for serum HGV RNA and/or anti-E2) was 38.9%, 69.5%, 64.5%, 17.0%, 25.5% and 39.5%, respectively. Neither clinical nor virological factors were associated with TTV viremia. The rate of ALT abnormality was significantly elevated in HCV RNA-positive (34.9%) than -negative (7.0%) residents (p < 0.001). HCV viremia was the only factor significantly associated with ALT elevation by multiple logistic regression (odds ratio: 6.96; 95% C.I.: 2.60-18.7). We concluded that in this HCV/HBV hyperendemic area, the prevalence of TTV DNA was high. No significant clinical factor was observed to be associated with TTV infection. TTV infection is not related to abnormal ALT levels and ALT abnormality was mainly attributable to HCV but not TTV, HBV or HGV infection.