Posttransfusion Hepatitis Of Unknown Etiology Research Articles

Molecular Epidemiology and Clinical Implications of TT Virus (TTV) Infection in Indian Subjects

This study was aimed at obtaining data on the epidemiology and clinical course of TT virus (TTV) infections among Indian subjects. The TTV is a nonenveloped DNA virus, first identified in the peripheral blood of individuals with posttransfusion hepatitis of unknown etiology. There has been much conjecture regarding the disease association of this virus. A total of 494 serum specimens from various groups of high-risk and control subjects were screened for TTV DNA by a semi-nested PCR, using the ORF1-derived N22 primers. The sera were also screened for the HBsAg surface antigen by an ELISA, HCV RNA by a 5' NCR-based RT-PCR and GBV-C/HGV RNA by a 5' UTR-based RT-PCR. The clinical and hepatic profiles of the various subjects were also studied. Seventy-one randomly picked TTV isolates were directly sequenced and their phylogeny was studied. TTV showed an overall positivity rate of 45.34% with a significant higher prevalence of 52.9% among the high-risk subjects as against a prevalence of 28% among healthy control subjects (P < 0.001). Abnormal liver function profiles were frequent among TTV viremic individuals and among the acute hepatitis cases studied a higher mortality rate correlated with a superimposed TTV infection. The 71 TTV isolates sequenced were found to belong to genotype 1a being closely homologous to TTV prototype TA278. The TT virus shows a significant prevalence in the Indian population, particularly among subjects at risk for acquiring parenterally transmitted infections. Our study corroborates a putative role of the virus in the etiology of liver disease, particularly in coinfection with other agents.

Novel TTV variants isolated in an epidemic of hepatitis of unknown etiology.

TT virus (TTV) is a recently discovered single-stranded DNA virus that has been reported to be associated with elevated transminase levels in the patients with posttransfusion hepatitis of unknown etiology. TTV prevalence is very high in the common population and its pathogenicity remains unclear. In this study, we performed an epidemiological study to investigate the infection rate of TTV and its role in an epidemic of unknown-etiology hepatitis. Moreover, two TTV isolates named L01 and L02 were cloned from the serum of a patient with unknown-etiology hepatitis. Eighty-one subjects were included in the study and were divided into two groups: 18 in the case group and 63 in the control group. TTVDNA was detected by nested PCR from sera samples. The infection rates of TTV in case and control groups were 33.3 and 38.9%, respectively. There was no significant difference between the two groups. Homology analysis showed that L01 had a very poor homology with other TTV isolates and L02, and L02 was 75.5% identical to JA10. The result does not support TTV as a causative agent in this epidemic. The genetic divergence between L01 and other TTV isolates beyond genotype, so it represents a new genotype of TTV.

TT virus infection in children and adults who visited a general hospital in the south of Brazil for routine procedure.

TT virus (TTV) is a newly described nonenveloped human virus, with a circular, negative-stranded DNA genome, that was first identified in the blood of a patient with posttransfusion hepatitis of unknown etiology. PCR primers and conditions used for TTV DNA amplification may greatly influence the level of TTV detection in serum. Three PCR assays, with different regions of the genome as targets, were used to test TTV DNA in 130 sera from children and adults visiting a hospital in the south of Brazil, most of them for routine procedure. Forty-four percent of adult sera and 73% of sera from children aged 0-10 years were TTV positive with at least one PCR assay. However, the three assays were able to detect only 33%, 35%, and 70% of the total positive samples. Our results showed a high prevalence of TTV infection in the south of Brazil, particularly among young children, and confirmed the necessity of performing several PCR assays to assess the true TTV prevalence in a determined population.

Changes of DNA titer and sequence variance of TT virus in hepatic disorders

TT virus (TTV) has been reported to occur in association with elevated alanine aminotransferase (ALT) levels in patients with posttransfusion hepatitis of unknown etiology. We examined whether the presence, change of DNA titer, or variation in sequence of this virus is associated with acute or chronic liver dysfunction in Japanese. We detected TTV by polymerase chain reaction (PCR) using primers generated from the conserved region of the TTV genome. Direct DNA sequencing of the original N22 region was used to characterize TTV isolates. We detected TTV DNA in 15 (25%) of 60 patients with liver dysfunction. Variants recovered from infected patients formed four genotypes/subtypes, corresponding to G1a, G1b, G2, and G4. Although TTV DNA titers in patients with G2 and G4 were lower than those with G1, TTV was consistently detected regardless of genotype/subtype. TTV infection continued for at least 1 year after normalization of ALT level in patients with acute liver dysfunction. Changes in DNA titer, substitutions of deduced amino acids, and variety of quasispecies of TTV were detected during the observation period, but no significant fluctuation in ALT level was found. We conclude that persistent infection, changes in DNA titer, and variation in sequence of this novel virus are not significantly related to hepatic disorders.

Infection with hepatitis A and TT viruses and socioeconomic status in Rio de Janeiro, Brazil.

The prevalence of antibodies directed against the enterically transmitted hepatitis A virus (HAV) was measured in 2 groups of people living in Rio de Janeiro, Brazil. Of 1,056 health care workers (HCWs), 778 (73.7%) were anti-HAV positive. A high prevalence of anti-HAV antibodies (85.7%) was also found among 274 voluntary blood donors (BDs). TT virus (TTV) is a DNA virus that has been found in the sera of patients with post-transfusion hepatitis of unknown etiology. Occurrence of virus shedding suggests that the fecal-oral route may be an important mode of TTV transmission, particularly in the developing world. The presence of TTV DNA was analyzed by PCR in the sera of 191 HCWs and 151 BDs. TTV was detected in 65.4% of HCWs and 79.5% of BDs. In both groups, a family income of < US$400 per month and a level of education of < 11 y of schooling were found to be risk factors for HAV infection. Furthermore, a low family income was associated with TTV viremia in the HCW group. However, the presence of TTV DNA was associated with neither low level of education nor anti-HAV positivity.

Indirect evidence of TTV replication in bone marrow cells, but not in hepatocytes, of a subacute hepatitis/aplastic anemia patient

The presence of a new DNA virus (TTV) has been reported in sera from patients with posttransfusion hepatitis of unknown etiology. The precise replication site of TTV, however, has not been established. In this study, the presence of TTV in liver autopsy material, and in bone marrow biopsy and autopsy samples taken from a subacute hepatitis/aplastic anemia patient was determined by PCR and Southern blot analyses. Liver cells were found to contain only TTV DNA and not mRNA. Bone marrow material, especially that taken at biopsy, contained high levels of TTV DNA. It is suggested that the TTV replication site was in the bone marrow rather than in the liver, and that TTV infection was the cause of this patient's aplastic anemia. The precise etiological association of TTV with hepatitis remains to be established. J. Med. Virol. 61:165–170, 2000. © 2000 Wiley-Liss, Inc.

Indirect evidence of TTV replication in bone marrow cells, but not in hepatocytes, of a subacute hepatitis/aplastic anemia patient

The presence of a new DNA virus (TTV) has been reported in sera from patients with posttransfusion hepatitis of unknown etiology. The precise replication site of TTV, however, has not been established. In this study, the presence of TTV in liver autopsy material, and in bone marrow biopsy and autopsy samples taken from a subacute hepatitis/aplastic anemia patient was determined by PCR and Southern blot analyses. Liver cells were found to contain only TTV DNA and not mRNA. Bone marrow material, especially that taken at biopsy, contained high levels of TTV DNA. It is suggested that the TTV replication site was in the bone marrow rather than in the liver, and that TTV infection was the cause of this patient's aplastic anemia. The precise etiological association of TTV with hepatitis remains to be established.

Seroepidemiology of TT virus infection and relationship between genotype and liver damage.

TT virus (TTV) has been identified in patients with posttransfusion hepatitis of unknown etiology and is thought to be a new hepatitis virus. We determined the extent of TTV infection in the Japanese general population and the relationship between TTV DNA genotype and liver damage. In 1998, we tested 847 serum samples for TTV. TTV DNA was assayed by a nested polymerase chain reaction and classified into three different genotypes and eight subtypes. TTV DNA was detected in 25.3% and 32.4% of the inhabitants of the two areas studied, respectively. The genotype distribution was similar in both areas. G1, G2, and G3 were 60%, 20%, and 5%, respectively. Of the 20 subjects with TTV DNA alone and elevated serum ALT levels, 18 were G1, one was G2, and one was G3. TTV infection is endemic in the Japanese general population studied. The main TTV genotype, G1, may be related to the ensuing liver damage.

Transfusion transmitted virus infection in general populations and patients with various liver diseases in south China.

Although several specific detecting methods had been applied to determine the hepatitis virus, there was a lot of cryptogenic hepatitis without any known hepatitis infectious marker[1]. The prevalence of hepatitis G virus (HGV) (also known as GB-C virus) infection has been reported to be 5%-13% in patients with non-A-E hepatitis and cirrhosis, however, there is little evidence suggesting that HGV causes hepatitis in human[2-6]. Although cryptogenic liver diseases are almost certainly related to a variety of etiologies, one or more as-yet-unidentified infectious agents are likely to account for a proportion of these cases. In December 1997, a novel DNA virus was reported by Nishizawa et al[7] to be associated with elevated aminotransferase levels in patients with post-transfusion hepatitis of unknown etiology (non-A-G hepatitis). This virus was designated transfusion transmitted virus (TTV). Then, Luo et al[8] and Wei et al[9] also detected TTV in the sera of patients from an outbreak of cryptogenic hepatitis in south China. And TTV was also detected in patients with post-transfusion hepatitis in China[10]. In subsequent analyses, TTV is an un-enveloped single-stranded DNA virus for which a sequence of 3800 bases was determined[11]. Evidence of potential hepatotropism of TTV was reported with TTV DNA detected in liver tissue[12]. Histopathological study indicated that the characteristics of liver histology of TTV infected patients are portal inflammation and interlobular bile duct damage[13]. TTV was proposed as the part of causative agent of non-A to G hepatitis. Seroepidemiological studies have shown TTV to have global distribution[12,14,15]. Although the potential association of TTV with cryptogenic hepatitis is intriguing, the pathological and clinical significance of this virus remains to be established. To assess more thoroughly the etiological role of TTV in the causation of hepatitis, we determined the frequency of TTV infections and their relationship to liver disease in several cohorts of liver diseases and rural population.

Age-specific prevalence and transmission of TT virus.

TT virus (TTV) is an unenveloped, single-stranded DNA virus that was discovered recently in the sera of Japanese patients with posttransfusion hepatitis of unknown etiology. A high prevalence of TTV infection in blood donors of several countries, including Brazil, has been demonstrated. To study the variation in TTV prevalence between different age groups, sera from 223 individuals without liver disease, aged 0-80 years, were tested by the polymerase chain reaction for the presence of TTV DNA. All subjects were inhabitants of the city of Rio de Janeiro, Brazil. The prevalence increased continuously with age (P <.001), from 17% among children under the age of 11 years, to 57% in people older than 50 years. To assess vertical transmission, sera from 105 unselected, consecutive parturient women attending a public maternity hospital were paired with cord bloods and examined for the presence of TTV DNA. Thirty-seven (35%) mothers were found to be TTV infected. Seven cord bloods were also positive, suggesting the possible transplacental transmission of the virus. Furthermore, a direct correlation between TTV viremia and presence of antibodies to the enterically transmissible hepatitis A virus (HAV) was observed in this group of women, with a relative risk of TTV infection of 5.09 (95% confidence interval 0.76-34.03) for women with anti-HAV, compared with women without. This finding suggested that the fecal-oral route might be an important route of TTV transmission.

TTV-DNA IN SERA OF PAEDIATRIC PATIENTS WITH CRYPTOGENIC HEPATITIS

11 Background Recently a new DNA virus has been reported in patients with posttransfusion hepatitis of unknown etiology, in blood donors and in patients with cryptogenic cirrhosis and fulminant hepatic failure. Neverthless the several reports, it is not yet clear the role of TTV in the pathogenisis of acute and chronic liver disease. Furthermore, there are no data on the role of TTV in paediatric patients with cryptogenic hepatitis. Patients and Methods Stored sera of eight children (age, range: 4-10 years) who referred to our Department for cryptogenic hepatitis were retrospectively studied. All patients had no serological markers for A-G hepatitis, HIV, TORCH, EBV. Metabolic and genetic causes of liver disease were also excluded. TTV DNA was extracted from serum samples using DNAzol reagent. Semi-nested PCR was used to amplify 279 bp of TTV DNA, as previously described by Naoumov NV et al. Results TTV-DNA has been found in all sera tested from one out eight children studied. The patient presented in 1996 at the age of four years old for cryptogenic hepatitis and associated extrahepatic symptoms, namely arthritis, myositis, skin rush, recurrent fever and weight loss. Liver biopsy showed the histological picture of mild chronic hepatitis and mild bile duct proliferation. Any therapeutic attempt with steroidal and non-steroidal anti-inflammatory agents was without benefit on the hepatic and systemic symptoms. The enteral nutrition with elemental formulas, established for the appearance of abdominal pain and gastrointestinal signs of inflammatory bowel disease, resulted effective in restoring nutritional status but did not significantly affect the hepatic function. Conclusions The TTV-DNA was detected in a child with a clinical history of idiopathic chronic hepatitis and associated autoimmune extrahepatic symptoms. Further follow-up and evaluation will be necessary to clarify the exact role of TTV in the pathogenesis of hepatic and extrahepatic manifestations in this patients, especially for a more appropriate therapeutic approach. Larger investigations of TTV in paediatric patients with posttransfusional and cryptogenic hepatitis are required.

Detection rates of TT virus among children who visited a general hospital in Japan.

Recently, genomic DNA of the novel TT virus (TTV) was isolated from patients suffering from posttransfusion hepatitis of unknown etiology. We examined sera from 197 children who visited the Department of Pediatrics at Toyohashi National Hospital. Sera were tested for TTV DNA by seminested polymerase chain reaction (PCR) using a set of primers synthesized according to the published TTV sequence. Ten children were found to be positive for TTV (5.1%). All positive PCR products were directly sequenced in both directions using a fluorescent dye terminator cycle sequencing system. The sequences were compared by a multiple sequence alignment and a phylogenetic tree was constructed. The phylogenetic tree showed that two of the TTV isolates found in the present experiment did not belong to any of the phylogenetic groups previously reported.

Distinct genotypes of a nonenveloped DNA virus associated with posttransfusion non-A to G hepatitis (TT virus) in plasma and peripheral blood mononuclear cells.

TT virus (TTV) is a nonenveloped, single-stranded DNA virus with little sequence homology to known viruses, and associated with elevated transaminase levels in the patients with posttransfusion hepatitis of unknown etiology. The DNA of TTV was detected, by semi-nested polymerase chain reaction, in peripheral blood mononuclear cells (PBMC) from the 30 healthy individuals with circulating virus in plasma. A sequence of 222 bases was determined on 6-10 TTV DNA clones each from plasma and 6 clones -each from PBMC from eight individuals selected at random from this group. TTV can be classified into genotypes separated by an evolutionary distance > 0.30, which can be divided further into subtypes separated by that of 0.15. Three individuals possessed two different TTV variants of distinct genotypes, with predominant genotypes different between plasma and PBMC. Another possessed TTV of the same genotype in both the plasma and PBMC, but clones with a subtype not seen in plasma were observed in PBMC. A third individual had TTV variants with or without a deletion mutation, and those with the deletion mutation abounded only in PBMC. The remaining three individuals were infected with TTV with the same sequence both in plasma and PBMC. These results indicate that TTV variants with phylogenetic differences could infect the same individual, and that some variants would have a predilection for PBMC. It remains to be seen, however, if TTV replicates in PBMC or whether it has been sequestered before its evolution in the host.

TT virus infection among blood donors and patients with non-B, non-C liver diseases in Korea

Background/Aims: A novel virus, designated the TT virus (TTV), was isolated from the serum of a patient with posttransfusion hepatitis of unknown etiology, in Japan. Subsequently, TTV was suggested to be a causative agent in a proportion of cases with cryptogenic hepatitis in Japan. This study aimed to elucidate the significance of TTV infection in cases with cryptogenic liver disease in Korea, a neighbor of Japan. Methods: The prevalence of TTV infection was studied in 120 patients with liver diseases, including 85 patients diagnosed as having non-B, non-C liver diseases. As controls, 220 blood donors were also examined. TTV DNA was detected by polymerase chain reaction, and the sequence was analyzed by phylogenetic analysis. Results: Fourteen (14.0%) of 100 accepted blood donors, 23 (19.2%) of 120 rejected blood donors, and 15 (17.6%) of 85 patients with non-B, non-C liver diseases were positive for TTV DNA. The prevalences of TTV infection among these groups were not significantly different. Phylogenetic analysis suggested the existence of four major genotypes of TTV. The proportions of each genotype among patients with non-B, non-C liver diseases were not different from those among accepted blood donors. Conclusions: TTV exists in Korea, but the prevalence among patients with non-B, non-C liver diseases was almost the same as that among blood donors. TTV may not be the main causative agent of cryptogenic liver disease in Korea. The relationship between non-B, non-C liver diseases and TTV genotype remains unclear, although TTV can be classified into four genotypes.

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. J. Med. Virol. 57:259–263, 1999. © 1999 Wiley-Liss, Inc.

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.

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 ∼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.

Prevalence of TT virus in patients with fulminant hepatic failure in Japan.

A novel virus (TT virus) was isolated from patients with posttransfusion hepatitis of unknown etiology. We studied the prevalence of TT virus in 26 patients with fulminant hepatic failure without risk factors, including blood transfusion, and also examined 106 healthy blood donors as controls. We assayed serum TT virus DNA by seminested polymerase chain reactions and also examined the genotypes of this virus. Serum was obtained at admission from patients with fulminant hepatic failure. Serum samples at admission from seven (27%) of the 26 patients were positive for TT virus DNA. There were no differences in clinical findings, duration from onset to coma, or results of laboratory tests in patients with and without TT virus DNA. However, all 7 patients with TT virus died, whereas 9 of the 19 patients without TT virus died. The outcome for patients with fulminant hepatic failure and TT virus was significantly worse than for patients without the virus (P = 0.0227). TT virus was also detected in 29 (27%) of the 106 healthy blood donors. The genotype of the TT virus was mainly 1a in both groups. There were no differences in the rate of positivity and the genotypes of TT virus between patients with fulminant hepatic failure and healthy blood donors. TT virus infection may not cause severe hepatitis, such as fulminant hepatic failure, but it may indicate a poor outcome in such patients.

TRANFUSION-TRANSMITED VIRUS (TTV) IN BRAZIL. PRELIMINARY REPORT

TTV is a recently discovered DNA virus, isolated from a patient with post-transfusion hepatitis of unknown etiology by Japanese researchers. In the present study, we evaluated the presence of TTV among chronic liver diseases patients in São Paulo and Pará states, representing two geographically distinct Brazilian regions. TTV DNA was found in 21/105 (20%) and 9/20 (45%) cases from São Paulo and Pará States, respectively. DNA sequence data confirmed the presence of TTV genotypes 1a and 2a, as well as other genotypes not yet described. In conclusion, TTV is present in chronic liver diseases cases from Southeast and North Brazil. However, further studies involving healthy populations are necessary before establishing any causal relationship among TTV and human hepatitis.

Partial ∼2.4-kb sequences of TT virus (TTV) genome from eight Japanese isolates: diagnostic and phylogenetic implications

Recently, a new single-stranded DNA virus, TT virus (TTV), was molecularly cloned from a patient with posttransfusion hepatitis of unknown etiology, and its causal relationship to non-A–G hepatitis is being investigated. However, the only method to diagnose TTV infection has been polymerase chain reaction (PCR) on the basis of very limited information on its genome. To improve diagnostic efficiency as well as to understand better the genetic characteristics of TTV, we determined a partial ∼2.4-kb sequence of the TTV genome from eight Japanese isolates. The sequenced region covered a long open reading frame (ORF-L) coding for a protein of 768–770 amino acids, which was highly arginine-rich in its N-terminus and had three or four asparagine-linked glycosylation sites clustered in its central portion. Our eight sequences and the prototype TTV sequence (TA278) taken together, these Japanese isolates of TTV were classified under two distinct genotypes. Using PCR primers designed on the observed heterogeneity among separate isolates, we identified an extreme variant whose nucleotide similarity to other isolates was only about 65%. Comparison of the ORF-L-encoded protein of TTV with those of known single-stranded DNA viruses suggested a possibility that TTV might be related to chicken anemia virus belonging to the Circoviridae family rather than to the Parvoviridae.