A comparative study of TTV co-infection in patients with chronic liver disease B, C and non-B non-C]

The TTV DNA were examined in patients with chronic liver diseases B (n = 35), C (n = 44) and non-B non-C (n = 19). The clinical background, liver function and liver histological finding were compared in patients with or without TTV infection. The prevalence of TTV in patients with chronic liver diseases B, C and non-B non-C were 37.1%, 27.3% and 52.6%, respectively. There was no significant difference in liver function test between TTV positive and negative patients with chronic liver diseases B and C. The gamma-GTP level of TTV positive patients were significantly higher than that of TTV negative patients with chronic liver diseases non-B non-C. The histological findings were similar between patients with or without TTV infection. We concluded that even though the co-infection of TTV in patients with chronic liver diseases B and C was high, TTV does not act as a liver injury agent. The relationship between TTV and non-B non-C chronic liver diseases is unclear.     

Persistent TT virus infection does not contribute to the development of non-A to -G hepatocellular carcinoma. A case-control study of 19 patients in Japan

We tested the sera of patients with non-A, non-B, non-C, non-G (non-A to -G) hepatocellular carcinoma (HCC) for the presence of TT virus (TTV) DNA and clinicopathologically elucidated the relationship between TTV infection and hepatocarcinogenesis. The study cohort consisted of 19 patients with non-A to -G HCC. Detection of TTV DNA was performed by the nested polymerase chain reaction according to a previously published method. TTV DNA was detected in the sera of 9 (47.4%) of the 19 patients with non-A to -G HCC. The clinical background factors and blood biochemical parameters of the TTV-DNA-positive and -negative HCC patients did not significantly differ. Three TTV-DNA-positive and 2 TTV-DNA-negative patients underwent surgical resection of the HCC. The histological findings in the non-cancerous liver tissue of the TTV-DNA-positive and -negative patients did not significantly differ. In conclusion, TTV infection does not affect the features of non-A to -G HCC.     

TTV positivity and transfusion history in non-B, non-C hepatocellular carcinoma compared with HBV- and HCV-positive cases

The prevalence of TT virus (TTV) and its rate of transmission through transfusion were investigated to determine its possible hepatocarcinogenic role in non-B, non-C hepatocellular carcinoma (HCC) as compared with that in hepatitis B virus (HBV)- and hepatitis C virus (HCV)-positive HCC. Its transfection route in TTV-positive cases was also studied. Serum was positive for TTV in 77.8% (7/9) of HBV-positive, 36.4% (12/33) of HCV-positive, and 63. 6% (7/11) of non-B, non-C cases of HCC. The rate of transmission through transfusion was 52.4% (11/21) in HBV-positive, 40.1% (61/152) in HCV-positive, 33.3% (2/6) in HBV+HCV-positive, and 40% (8/20) in non-B, non-C HCCs, while it was 48.3% (14/29) in TTV-positive and 39.3% (11/28) in TTV-negative cases. The association between TTV and HCC was limited, and the main route of infection of TTV was not through transfusion.     

Incidence of TT virus infection in patients with non-A to G liver disease]

The sera of patients with liver disease associated with non-A to G hepatitis were examined for the presence of TTV DNA. These patients included 18 cases with AH, 8 cases with CH, 6 cases with LC, 4 cases with HCC, and 36 cases with blood donors. The detection of TTV DNA was performed as described by Nishizawa et al. TTV DNA was detected in 60.0%, 62.5%, 66%, 50%, 28% of the patients with AH, CH, LC and HCC, respectively. Among the patients with AH, the aminotransferases and total bilirubin values were lower in the TTV DNA-positive than -negative patients. Among the patients with chronic liver disease, however, there were no differences in the blood chemistry results between the TTV DNA-positive and -negative patients. The histological study of the liver tissues from a TTV positive patient with CH showed no evidence of necro-inflammatory reaction, although there was evidence of irregular regeneration in the TTV DNA-positive a patient. These results suggest that TTV infection may modify the pathological condition of the liver disease.     

Involvement of TTV, a new infectious factor in post-transfusion hepatitis, non A-non G]

Post-transfusion hepatitis developed in 6 of 447(1.3%) patients who received transfusion even after 1992 when HCV screening by PHA method was started. The six patients were suggested as hepatitis, non-B, non-C, non-G type. Of the six patients, 4 were found to be infected with TTV, which was identified in one of the patients. The patients became positive for TTV DNA before or almost the same time as the development of hepatitis and their amounts of TTV DNA were varied depending on the ALT level, suggesting that their hepatitis might be caused by TTV. The patients who presented hepatitis became positive for TTV DNA in the 6-10th week after transfusion, whereas more than half of the patients with a slight hepatic disorder became positive in the 2-4th week after transfusion. In addition, prolonged infection with TTV was only observed in nearly half of 23 patients.     

The association of TTV genetic variant with liver disease]

TT virus (TTV), a novel DNA virus, has been reported in non-A to non-G posttransfusion hepatitis patients. Among 61 Japanese patients with liver diseases of non-B and non-C etiology, TTV DNA was detected in 15(25%) patients. The N22 region of TTV was sequenced and compared with the published sequence. Four genetic groups corresponding to G1a, G1b, G2 and G4 were formed. TTV was detected persistently regardless of its genotype/subtype. However, G2 and G4 contained 10 to 100 folds lower in titer than G1. Co-existing multiple mutants and subtypes were identified in one case. Since changes of TTV DNA titer and appearance of deduced amino acid substitution was not linked to ALT levels, the association of TTV to chronic liver diseases seemed low.     

Seroepidemiological survey of TT virus (TTV) infection in an endemic area for hepatitis C virus]

Seroepidemiological survey of TT virus (TTV) infection was performed in the inhabitants living in an endemic area for hepatitis C virus (HCV) in Gifu prefecture, Japan. In this area, 482 of 1062 inhabitants (45.4%) were seropositive for HCV relative antibodies. TTV-DNA was detected in the sera from 12 of 88 inhabitants (13.6%). The positive rate of TTV-DNA had no relation to sex or age. The TTV DNA-positive rate of the inhabitants with HCV infection was 21.4% higher than that of the inhabitants without HCV infection 10.0%. In the present survey, the rate of liver dysfunction of TTV DNA-negative inhabitants was not different from that of TTV DNA-positive inhabitants. Such results seem to suggest that TTV infection is not related to the liver disease in the area.     

High prevalence of TT virus(TTV) in patients with non A to non G fulminant hepatitis: differences of clinical features and prognosis between TTV positive and negative patients]

We detected TTV-DNA in sera from 36 patients with fulminant hepatitis(FH) and evaluated differences in clinical features and prognosis between TTV-DNA positive and negative patients with nonA-nonG FH. TTV-DNA in sera was measured by nested PCR. Twenty of 36 patients with FH were diagnosed nonA-nonG FH. The TTV-DNA in sera was detected in 14 patients(38.9%) with FH, 9(64%) showed nonA-nonG FH and 3 were HBV FH and 2 were drug-induced FH. Although we compared clinical features(gender, age, distribution history of blood transfusion, initial symptoms of hepatitis, and liver function tests) and prognosis between TTV positive and negative patients with nonA-nonG FH, there were no significant differences between the two groups. These data suggest that although TTV may be a infectious agent related to nonA-nonG FH, further study is needed to clarify the role of TTV in the pathogenesis of FH.     

TT virus infection in patients with hepatocellular carcinoma associated with non-A to G hepatitis: histopathological study]

To study if TTV infection is involved in the development of hepatocellular carcinoma (HCC), we tested the sera of 19 patients with HCC associated with non-A to G hepatitis for the presence of serum TTV DNA, and compared the blood chemistry values and liver histology of the patients in the TTV DNA-positive and -negative groups. Detection of TTV DNA was performed described as Nishizawa, et al method. TTV DNA was detected in the sera of 47.4%. There were no significant differences in the blood chemistry results and other tests between the TTV-positive and -negative patients. Histological examination of the non-tumor regions of the liver showed that there were no significant differences in the number of areas and characteristics of the necro-inflammatory reactions, the degree of staging and irregular regeneration of hepatocyte between the two groups. These results suggest that the development of HCC in patients with non-A to G hepatitis is not associated with TTV infection.     

Pathogenic significance and organic virus levels in patients infected with TT virus.

Previous reports documented the recovery of a DNA virus from a patient with posttransfusion non-A-G hepatitis and named TT virus (TTV). Although the virus was initially detected as a causative agent of hepatitis, there is doubt about its pathogenicity. The aim of this study was to clarify the relationship between TTV and liver diseases. Histopathological examination of liver biopsies from 14 patients with TTV genotype 1 positive non-B, non-C and non-G chronic hepatitis showed mild fibrosis and periportal/piecemeal necrosis. Using the real-time detection (RTD)-PCR method, we found that TTV DNA levels of genotype 1 in liver samples from 3 such patients were 100- to 1,000-fold higher than those in the paired serum samples. Further investigation using various tissues from 2 autopsies of patients with hepatitis C with hepatocellular carcinoma revealed that the concentrations of TTV DNA in the liver were also higher than in serum samples. However, the highest TTV DNA concentrations in these 2 autopsies were found in the lung and bone marrow, respectively. Our results suggest that TTV may replicate in various tissues including the liver and may cause only mild liver damage.     

Roles of TT virus infection in various types of chronic hepatitis

An unenveloped single-stranded virus, which might be a causative agent for posttransfusion non-A-G hepatitis, was recently found and named "TT virus" (TTV). There is still controversy over the role of TTV in chronic hepatitis. Therefore, we have examined the prevalence of TTV in various types of chronic hepatitis in Japan. TTV DNA was detected in 11 of 40 patients (27.5%) with non-B, non-C chronic hepatitis, 13 of 46 patients (28.3%) with type B chronic hepatitis, 21 of 55 patients (38.2%) with type C chronic hepatitis, and 41 of 131 subjects (31.3%) with normal liver function tests. The positivity rate for TTV DNA tended to increase with age. The detection rate did not differ statistically between non-B, non-C chronic hepatitis and type B or type C chronic hepatitis, or normal subjects. The distribution of TTV genotypes was not significantly different among them. Clinical characteristics of the chronic illness were similar for patients with or without TTV in all hepatitis groups. The etiologic role of TTV in chronic hepatitis is not confirmed from the statistical and clinical standpoint.     

Detection of TT virus (TTV) in non-B, non-C hepatitis patients with hepatocellular carcinoma, and clinical features of these patients]

A novel human DNA virus, TTvirus (TTV), was identified from a patient with posttransfusion hepatitis of unknown etiology. It is thought to be a new hepatitis virus, but the clinical significance of this virus is uncertain. We investigated the frequency of TTV viremia by PCR in 39 non-B, non-C hepatitis (NBNC) patients with hepatocellular carcinoma (HCC), and clinical features of these patients. TTV viremia was detected in 20 (51.3%) of 39 NBNC hepatitis patients with HCC. Liver cirrhosis (LC) were found in 11 (55%) of 20 TTV-positive patients and 16 (84%) of 19 TTV-negative patients (p < 0.05). The levels of AST, LDH, LAP, gamma GTP in TTV-positive patients were significantly higher than those in TTV-negative patients (p < 0.05). (AST: 58 +/- 26 vs 42 +/- 23 IU/l, LDH: 468 +/- 127 vs 366 +/- 123 IU/l, LAP: 339 +/- 242 vs 206 +/- 80 IU/l, gamma GTP: 207 +/- 207 vs 105 +/- 107 IU/l) These results suggest clinical differences between TTV-positive and TTV-negative patients in NBNC hepatitis patients with HCC.     

Histological findings of TTV-positive non-B non-C chronic hepatitis patients]

TT virus has been reported in association with patients with acute and chronic liver disease of unknown etiology. In order to estimate the pathogenesis of TTV, we investigated the liver histology in the patients of TTV-positive chronic hepatitis. The findings frequently observed in TTV-DNA positive cases were changes in liver parenchyma such as focal necrosis, hepatocyte degeneration or fatty change of various degree. On the other hand, degree of chronic inflammation in portal areas such as lymphocyte infiltration, piecemeal necrosis or fibrosis were relatively mild, which might suggest the good prognosis in TTV-positive cases. However, we could not find any differences in liver histology between TTV positive and negative patients.     

Detection of TT virus (TTV) in Japanese hemodialysis (HD) patients]

The clinical and epidemiological studies on TT virus (TTV) were achieved in 44 Japanese HD patients. TTV-DNA was detected in 29.5% of HD patients, and the percentage was higher than that reported in normal populations. HBsAg, anti-HBc, anti-HCV and HGV-RNA were positive in 6.8%, 36.4%, 22.7% and 2.3%, respectively. One of three HD patients with TTV had liver disorders. In comparison between TTV positive and negative groups, there were significant differences of anti-HBc and total cholesterol value.     

TT virus infection does not affect the clinical profiles of patients with hepatitis B and C in Yanbian City,China

China is an area of high endemicity for viral hepatitis, and the molecular epidemiological investigation of TT virus (TTV) infection is of interest. In the present study, we investigated the epidemiology, clinical significance and molecular characteristics of TTV infection in patients with chronic hepatitis B and C in Yanbian City, China. Serum samples obtained from 74 patients with hepatitis B and hepatitis C who visited Yanbian Hospital, located in northeast China, were analyzed in this study. The study group included 22 cases of chronic hepatitis B (B-CH), 17 cases of liver cirrhosis B (B-LC), 7 cases of hepatocellular carcinoma (B-HCC), 16 cases of chronic hepatitis C (C-CH), 11 cases of liver cirrhosis C (C-LC) and 1 case of hepatocellular carcinoma (C-HCC). Detection of TTV DNA was performed as described by Nishizawa et al. The second-round PCR products from 7 subjects were sequenced, followed by investigation of nucleotide homology and phylogenetic analysis. TTV DNA was present in 18.2, 5.9, 28.6, 6.3, 9.1 and 0% of the patients with B-CH, B-LC, B-HCC, C-CH, C-LC and C-HCC, respectively. The highest prevalence of TTV infection was seen in the groups aged 40-50 and over 60 years. There was no significant correlation between the presence of TTV DNA and the clinical parameters in patients with hepatitis B and C. The various isolates showed 97.9-100% with isolates reported previously from Japan and 98.4-100% with isolates reported previously from China. Nucleotide sequence analysis revealed that the Yanbian isolates could be classified in the same group as the Japan and China isolates. We concluded that chronic coinfection with TTV did not affect the serological features of chronic hepatitis B and C in China, as found in Tokyo, Japan.     

Positivity rate of TTV-DNA in patients with acute liver injury of undetermined etiology]

To elucidate a role of TTV infection in patients with acute liver injury, TTV-DNA in the sera from 97 patients with acute liver injury of various etiology were determined according to Okamoto's method. Out of 77 patients with acute liver injury of determined etiology, 31 patients(40.3%) showed TTV-DNA positive, and out of 15 patients with acute liver injury of undetermined etiology, 8 patients(53.3%) showed TTV-DNA positive. These results suggested no evident role of TTV in patients with acute liver injury was shown. Further study including genotype and quantitative determination of TTV-DNA and antibody assay is needed.     

TTV materno-infantile infection--a study on the TTV frequency in Japanese pregnant women and the natural history of TTV mother-to-infant infection]

We preliminarily describe the frequency of TTV in Japanese pregnant women, non-parenteral, postnatal materno-infantile transmission of TTV, and 2 cases in which infantile development of the TTV carrier-state seemed to have occurred by vertical infection. The sera of 85 hepatitis B, C and G-positive and 36 non-pathological pregnant Japanese women were screened for the presence of TTV DNA with a use of semi-nested PCR. The positive rates were 25.9 and 27.8%, respectively. No significant differences were gained between these two groups. Twenty-one infants were born to the TTV carrier women. Of them, 9 infants (42.9%) sero-converted to TTV DNA-positive after their age of 4 months. Among the infants who were breast-fed, the positive sero-conversion rate of TTV DNA tended to increase as the length of the breast feeding period increased. Serum AST/ALT levels stayed within normal upper limits in the 9 infants. This study indicates the frequent, and furthermore, certain possibility of non-parenteral (i.e., via breast milk), postnatal vertical infection of TTV.     

Current tests for antibody to hepatitis b core antigen used to screen donors for non-A, non-B hepatitis are comparable to the original radioimmunoassay for hepatitis B core antigen

Prospective studies have shown a relationship between the transfusion of donor blood which is positive for antibodies to hepatitis B core antigen (anti-HBc) and an increased incidence of non-A, non-B hepatitis. The anti-HBc test was selected on the assumption that epidemiologic circumstances predisposing donors to hepatitis B infection also might favor exposure to non-A, non-B hepatitis. Current radioimmunoassays (RIA) and enzyme-linked immunoassays (EIA) for anti-HBc utilize hepatitis B core antigen (HBcAg) prepared by recombinant DNA technology, whereas the original RIA anti-HBc assay used HBcAg derived from hepatitis B virions. In the current study, 1329 sera were evaluated of which 23.3 percent were anti-HBc positive. The results indicate that sensitivity, specificity, and positive and negative predictive values of the current EIA and RIA tests for anti-HBc (Abbott Diagnostic Laboratories) are virtually identical to the original RIA test kit. In addition, all donor samples (128 specimens) administered to 57 cases of non-A, non-B hepatitis that were prospectively followed at Baylor College of Medicine for the Transfusion-Transmitted Viruses (TTV) Study group were retested with the EIA-recombinant anti-HBc assay. All 21 samples which were reactive in the original RIA anti-HBc test also were positive by the current EIA procedure. One sample was EIA positive/RIA negative, and 106 other samples were negative by both assays. Thus, commercial anti-HBc kits based on HBcAg derived by recombinant DNA technology, should retain their predictive value for reducing the incidence of non-A, non-B hepatitis as described in the prospective studies.     

A novel unenveloped DNA virus (TT virus) associated with acute and chronic non-A to G hepatitis.

In 1997, a novel DNA virus was isolated from the serum of a patient with posttransfusion hepatitis of unknown etiology in Japan, and it was named TT virus (TTV) after the initials of the index patient. TTV is a nonenveloped, single-stranded and circular DNA virus, and its entire sequence of approximately 3.9 kb has been determined. For being a DNA virus, TTV has a wide range of sequence divergence, allowing the classification into at least 16 genotypes separated by a sequence difference of >30% from one another. The nucleotide sequence of the noncoding region of the TTV genome is conserved, whereas that of the coding region is highly variable. TTV strains with extremely high sequence divergence are common in the same individuals, thereby indicating a mixed infection of TTV strains of different genotypes. An association is found between hepatitis of unknown etiology and the TTV genotypes which are detectable by PCR with primers deduced from the N22 region (genotype 1) in the open reading frame 1 encoding the capsid protein. It would be important to select the primers for specific detection of the TTV genotypes associated with clinical diseases, to further evaluate the capacity of TTV to induce acute and chronic liver disease as well as extrahepatic manifestations.     

输血传播病毒感染与丙型肝炎病毒感染的相互影响

目的了解输血传播病毒(TTV)与丙型肝炎病毒(HCV)重叠感染的发生率,探讨TTV感染与HCV感染的相互影响。方法采用酶联免疫吸附试验(ELISA)法检测血清中人类免疫缺陷病毒(HIV)、乙型肝炎病毒(HBV)、HCV、庚型肝炎病毒(HGV)及TTV标志物,应用巢式聚合酶链反应(n-PCR)技术检测血清TTV DNA,用速率法或终点法检测血清肝功能指标,用放射免疫法检测血清肝纤维化指标,用超声诊断仪检查肝胆脾形态及动态指标;应用SPSS 11.0软件分析比较肝功能检测结果、肝纤维化指标检测结果及肝脾形态和动态指标改变的差异。结果TTV/HCV重叠感染占TTV感染的69.6%(39/56),占HCV感染的61.9%(39/63)。TTV、HCV感染与TTV/HCV重叠感染肝功能检测结果差异有统计学意义(P<0.05);肝纤维化指标检测结果差异有统计学意义(P<0.05)。结论TTV/HCV重叠感染存在很高的发生率,感染者肝损程度较重,临床进程加快,有肝纤维化趋势。