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The aim of this study was to determine the transfusion transmitted Virus (TTV) prevalence in three groups of population from Abidjan, Côte d'Ivoire. The A group contained 39 multitransfused patients, the B group contained 10 blood donors supposed to be healthy persons which have never been transfused and the group C contained 43 patients with chronic liver pathology. In this last group, 33 patients had HBV positive serology and the 10 others, HCV positive serology. We used PCR to investigate TTV in patients serum. Detection rates were comprised between 67% and 82%. This is the first study to provide information about the high portage of TTV in ivorian population.

Background: Little is known about the pathogenic role and the endemic situation of transfusion transmitted virus (TTV)., Objectives: In this study, a molecular assay for detection of TTV based on automated nucleic acid extraction and real-time PCR was developed and evaluated. The new assay includes an internal control., Study Design: After optimization of the molecular assay, 103 clinical samples were studied retrospectively. All sera had been tested for anti-HCV and anti-HIV-1 antibodies earlier., Results: The amplification efficiency was found to be 102%. When clinical specimens were tested, 79 of 103 serum samples were found to be positive for TTV. There was no significant difference between various groups of patients. The internal control was detected in all negative and weak positive samples., Conclusions: This molecular assay proved to be suitable for routine detection of TTV in clinical samples. Moreover, a relative statement on the TTV serum load can be done.

Recent observations suggest that TT virus (TTV), in addition to liver, may also infect bone marrow. In this study, bone marrow samples and sera from 33 patients with haematological disorders and sera from 16 healthy controls were investigated for TTV DNA presence. Altogether TTV DNA sequences were demonstrated in bone marrow cells of 84.84% of patients. Moreover TTV DNA was detected in sera from 72.72% of patients and from 93.75% of controls. N22 sequences amplified from bone marrow cells and serum of 3 patients were analysed, after cloning: all these isolates were of type 2c and 2 or 3 variants were present in each isolate. After single strand DNA degradation, replicative forms were detectable in BM cells. This finding, in addition to the detection of variants similar in the BM and in the serum of the same patient could suggest that BM is a site of TTV replication (or one of the sites) from which the virus is spread in blood.

TT virus (TTV) and TTV-like viruses (TTVLs) have been reported to be associated with non-A-E hepatitis. To determine the rate of infection and genotypic characteristics of TTV in the United Arab Emirates (UAE), a total of 449 serum samples representing different populations in the UAE and comprising healthy as well as patients positive for HBsAg and HCV were screened. National subjects (n = 200) and non-nationals residing in the UAE (n = 249) were tested by PCR. The results obtained showed that the rate of TTV infection in healthy nationals, and those with HBsAg or antibody to HCV were 34.9, 97.9, and 95.7, respectively, compared to 89.1% (115/129), 89.2% (66/74), and 84.8% (39/46), respectively, in non-nationals. Sequence analysis of the untranslated region (UTR) using 71 clones generated from the PCR products of eight serum samples from healthy individuals (four nationals and four non-nationals) showed that 83.1% of the TTV clones were classified into groups 1-4, whereas 16.9% into possibly new genotype(s). The analysis also revealed that healthy national subjects carried multiple viruses. Phylogenetic analysis of representative sequences revealed clustering of clones into at least five major groups. Also, when compared to reference genotypes (from GenBank), two of our clones belonged to two previously identified genotypes. Non-significant gender differences were seen in all ethnic groups studied (P > 0.05). In conclusion, the rate of TTV infection in the UAE nationals is significantly lower (P < 0.05) than that of the non-nationals and several genotypes were isolated with common multi-infections., (Copyright 2004 Wiley-Liss, Inc.)

Objective: Hepatitis B virus (HBV) and hepatitis C virus (HCV) are major risk factors for hepatocellular carcinoma (HCC). The role of a novel DNA virus, designated SEN virus (SENV), in the etiology of liver cancer remains to be established. The aim of this study was to evaluate the association between SENV infection and the risk of HCC by conducting a hospital-based, case-control study among Thai patients., Methods: Eighty-six patients with HCC were enrolled and matched individually to a control according to sex, age (+/- 5 yr), and geographic background. The presences of HBV DNA, HCV RNA, and SENV DNA in stored serum samples were detected with the use of semi-nested polymerase chain reaction amplification., Results: Individuals who were infected with SENV did not have increased risk of developing HCC (OR=1.49, 95% CI=0.50-4.42). In contrast, those who were positive for HBV markers (hepatitis B surface antigen and/or HBV DNA) or HCV markers (anti-HCV and/or HCV RNA) had significant risk for HCC (OR=19.91, 95% CI=8.26-47.98 and OR=7.97, 95% CI=2.15-29.54, respectively). Moreover, coinfection with SENV did not further increase the risk of HCC among patients infected with HBV and/or HCV., Conclusion: Our data suggest that, unlike chronic HBV or HCV infection, SENV infection is not a risk factor for developing HCC in Thai populations.

Objective: To investigate the prevalence of newly identified single-chain DNA virus (SENV) infection in Shenzhen., Methods: Nested polymerase chain reaction (nPCR) was established using primers from ORF1 region of SENV genome. Six hundred and one sera samples from different populations were detected for SENV DNA (D and H subtype) by nPCR. Products of PCR were cloned into T-vector and sequenced., Results: The positive rates of SENV DNA in different populations were as followed: 27.8% in patients with hepatitis B, 22.2% in patients with hepatitis C, 26.9% in hemodialysis patients and 39.3% in IDUs. Among blood donors, the positive rates of SENV DNA were 28.1% in unqualified blood donors, 31.3% in blood donors with an elevated ALT levels and 15.1% in qualified blood donors. The infection rates of SENV in unqualified blood donors and blood donors with an elevated ALT levels were obviously higher than in qualified blood donors (chi(2) = 8.29, P < 0.01 and chi(2) = 6.03, P < 0.01). There was a 6.8% difference of nucleotide between SENV-D standard subtype and 6 isolates with 13.5% difference of nucleotide between SENV-H standard subtype and 4 isolates from Shenzhen., Conclusion: Results suggested that SENV infection was common in high-risk groups in Shenzhen.

Blood and gastric tissue biopsies of 34 patients with gastritis were tested for the presence of TT virus (TTV), a ubiquitous virus found in the blood of most humans. Thirty-one of these patients were TTV positive, and 27 patients had virus in both tissues. In addition, 13 of the patients who had TTV in gastric tissue were Helicobacter pylori positive. There was an association of higher TTV titers in gastric tissues of patients who were H. pylori positive than in those in whom the bacterium could not be detected. Furthermore, this association was stronger in H. pylori-positive patients with the presence of the cagA protein. Of 10 specimens in which genogroup determination was carried out in the gastric corpus, 5/5 that were H. pylori positive showed the presence of TTV genogroup 3, while for those that were H. pylori negative, 5/5 showed the presence of genogroup 1t. By contrast, genogroup 1 was found in the corpus of only one H. pylori-positive patient, and genogroup 3 in only one H. pylori-negative patient. The histological severity of gastritis did correlate significantly with loads in the gastric tissues. There was no significant difference in TTV titer in blood of patients regardless of H. pylori infection status. These findings pique interest in clarifying the role of TTV, alone or in association with H. pylori infection, in the pathogenesis of gastritis., (Copyright 2003 Wiley-Liss, Inc.)

Background: TT virus (TTV) is a recently discovered virus with a high DNA prevalence in different populations. Its role in pathogenesis is uncertain, particularly in immunocompromised patients., Patients and Methods: Prevalence of TTV-DNA was evaluated in a cohort of HIV-infected patients and in blood donors by nested PCR, using two different primer sets: T primers, derived from the open reading frame ORF1 region N22; B primers, derived from the untranslated region (UTR). Samples positive using T primers were also tested for TTV-DNA in peripheral blood mononuclear cells (PBMC) and followed up every 4 months., Results: The overall prevalence of TTV-DNA in HIV-infected patients was 37/376 (9.8%) using T primers and 223/333 (67%) using B primers; prevalence was higher in males (167/237, 70.5% vs 56/96, 58.3%; p = 0.033) and sub-Saharan Africans (22/23, 95.6% vs 201/310, 64.8% in other areas). Discordance was also observed in blood donors: 3.8% prevalence using T primers and 51.4% using B primers (also higher in males: 57% vs 37%, p = 0.056). TTV-DNA was detected in PBMC in 20/23 (87%) TTV-positive sera. Two-thirds of the serum samples remained positive over a 2-year follow-up period., Conclusion: TTV-DNA prevalence is higher when detected with primers derived from the UTR region and was highest in male and HIV-infected sub-Saharan Africans. TTV-DNA is frequently isolated in PBMC and chronic infection is common.

In 1998 viruses were isolated from tiger salamander larvae (Ambystoma tigrinum diaboli and A. tigrinum melanostictum) involved in North Dakota and Utah (USA) mortality events and spotted salamander (A. maculatum) larvae in a third event in Maine (USA). Although sympatric caudates and anurans were present at all three sites only ambystomid larvae appeared to be affected. Mortality at the North Dakota site was in the thousands while at the Utah and Maine sites mortality was in the hundreds. Sick larvae were lethargic and slow moving. They swam in circles with obvious buoyancy problems and were unable to remain upright. On the ventral surface, near the gills and hind limbs, red spots or swollen areas were noted. Necropsy findings included: hemorrhages and ulceration of the skin, subcutaneous and intramuscular edema, swollen and pale livers with multifocal hemorrhage, and distended fluid-filled intestines with areas of hemorrhage. Light microscopy revealed intracytoplasmic inclusions, suggestive of a viral infection, in a variety of organs. Electron microscopy of ultra thin sections of the same tissues revealed iridovirus-like particles within the inclusions. These viruses were isolated from a variety of organs, indicating a systemic infection. Representative viral isolates from the three mortality events were characterized using molecular assays. Characterization confirmed that the viral isolates were iridoviruses and that the two tiger salamander isolates were similar and could be distinguished from the spotted salamander isolate. The spotted salamander isolate was similar to frog virus 3, the type species of the genus Ranavirus, while the tiger salamander isolates were not. These data indicate that different species of salamanders can become infected and die in association with different iridoviruses. Challenge assays are required to determine the fish and amphibian host range of these isolates and to assess the susceptibility of tiger and spotted salamanders to heterologous virus isolates.

A polymerase chain reaction (PCR) method was developed for largemouth bass virus (LMBV). This iridovirus can cause a lethal disease of largemouth bass Micropterus salmoides, but also subclinically infects largemouth bass and other species of fishes. Oligonucleotide primers were designed to specifically amplify the major capsid protein gene of LMBV. The protocol for sample processing and PCR provided a method that was more sensitive than cell culture for detection of LMBV in fish. The specific amplification of LMBV also provided an improved method for confirming the identity of cell-culture isolates presumptively identified as LMBV.

A panel of six monoclonal antibodies (mAbs) against a grouper iridovirus (SGIV) were produced by immunization of Balb/c mice with purified virus preparations. Isotyping test revealed all the mAbs were IgG1. None of the mAbs possessed the ability to neutralize SGIV in cell cultures. Western blot showed that 4 mAbs reacted with 2 SGIV proteins at molecular mass of approximately 100 and 117 kDa in gradient-purified virus. Immunofluorescent studies showed that the two specific viral proteins VP100 and VP117 were localized within virus assembly sites in the cytoplasm of SGIV-infected grouper cells (GP). Fractionations of the iridovirus in a 20-60% sucrose gradient were detected successfully by all the six mAbs using immunodot blot. An antigen-capture enzyme-linked immunosorbent assay (ELISA) system, based on the use of mAb 7E11 for capture and a rabbit polyclonal antibody to SGIV for detection was developed. SGIV antigen was detected in gradient-purified virus and virus-infected grouper blood. These novel mAbs will facilitate the development of more specific and standardized diagnostic techniques for marine fish iridovirus.

Objectives: To determine the prevalence of TT virus (TTV) in a population of Danish hemodialysis patients and evaluate possible relations between TTV infection and elevated levels of C-reactive protein (CRP) and hypo-response to treatment with erythropoietin (EPO)., Material and Methods: Patients on maintenance hemodialysis at a single center were invited to participate. Demographic and clinical data were registered. Blood samples for virological and routine biochemical tests were drawn simultaneously. TTV DNA was detected using polymerase chain reaction (PCR). TTV viral load was estimated by means of semi-quantitative PCR. All patients were tested for hepatitis B, hepatitis C and GB virus C., Results: Of 252 patients, 204 (80.9%) gave their written informed consent to participate in the study. The prevalence of TTV was 68% and 50% of TTV-positive patients had a high TTV viral load. TTV-positive patients were significantly older than TTV-negative patients (p = 0.011). No relations were found between TTV infection and elevated levels of alanine aminotransferase (ALT) or CRP or hypo-response to EPO treatment. The mean hemoglobin concentration was 11.24 +/- 1.48 g/dl. Patients with a high TTV viral load had a lower level of hemoglobin (10.86 +/- 1.47 g/dl) than the others (p = 0.01). This trend suggested a positive relation between TTV infection and the number of blood transfusions. A restriction fragment length polymorphism assay suggested that patients were infected with different TTV strains., Conclusions: TTV is common in patients on maintenance hemodialysis. The presence of TTV is associated with increasing age. Patients with a high TTV viral load had lower levels of hemoglobin than the others. TTV infection is not related to elevated levels of ALT or CRP or to hypo-response to EPO treatment.

A wide variety of both DNA and RNA viruses affect the oral cavity. When considered in conjunction with cutaneous features, careful examination of the oral mucosa and oropharynx aids the clinician in making a diagnosis. Examination of the oral cavity should be incorporated as a regular component of the dermatologic examination because diagnostic clues are readily available to assist in the evaluation of infectious processes.

Infectious agents have been implicated in the pathogenesis of pediatric acute lymphoblastic leukemia (ALL). A novel human DNA virus, TT virus (TTV), has been identified in children possessing characteristics as an etiologic agent, making the virus a potential candidate. Analysis of specimens from children with ALL was performed to determine if an association exists. Archived specimens (79 peripheral blood mononuclear cells, PBMC/bone marrow cells, BMC, and 125 cerebrospinal fluid, CSF) obtained at diagnosis and during therapy from 28 pediatric patients were tested for TTV. All of the diagnostic BMC/PBMC were negative for TTV, but 7 patients had follow-up specimens that converted to TTV positivity. TTV was not detected in any CSF. The absence of TTV at diagnosis suggests TTV is unlikely to be causally associated with ALL in the cases analyzed. However, the data support TTV transmission through blood products and suggest that the CNS is not a sanctuary site for TTV.

Aim: To determine the frequencies of HGV and TTV infections in serum and saliva samples of non-hepatitis patients with oral diseases in Hangzhou area, and to understand the correlation between detected results of HGV RNA and/or TTV DNA in sera and in saliva from the same patients., Methods: RT-nested PCR for HGV RNA detection and semi-nested PCR for TTV DNA detection were performed in the serum and saliva samples from 226 non-hepatitis patients with oral diseases, and nucleotide sequence analysis., Results: Twenty-seven (11.9 %) and 21 (9.3 %) of the 226 serum samples were only positive for HGV RNA and TTV DNA, respectively. 10 (4.4 %) and 9 (3.9 %) of the 226 saliva samples were only positive for HGV RNA and TTV DNA, respectively. And 7 (3.1 %) of the serum samples and 2 (0.9 %) of the saliva samples showed the positive amplification results for both HGV RNA and TTV DNA. 12 saliva samples from the 34 patients (35.3 %) with HGV or HGV/TTV viremia and 11 saliva samples from the 28 patients (39.3 %) with TTV or HGV/TTV viremia were HGV RNA detectable, respectively, including two patients positive for both HGV RNA and TTV DNA in serum and saliva samples. No saliva samples from the 226 patients were found to be HGV RNA or TTV DNA detectable while their serum samples were negative for HGV or TTV. Homologies of the nucleotide sequences of HGV and TTV amplification products from the serum and saliva samples of the two patients compared with the reported sequences were 88.65-91.49 % and 65.32-66.67 %, respectively. In comparison with the nucleotide sequences of amplification products between serum and from saliva sample from any one of the two patients, the homologies were 98.58 % and 99.29 % for HGV, and were 98.65 % and 98.20 % for TTV, respectively., Conclusion: Relatively high carrying rates of HGV and/or TTV in the sera of non-hepatitis patients with oral diseases in Hangzhou area are demonstrated. Parts of the carriers are HGV and/or TTV positive in their saliva. The results of this study indicate that dentists may be one of the populations with high risk for HGV and/or TTV infection, and by way of saliva HGV and TTV may be transmitted among individuals.

In 1997, a new DNA virus was cloned by a Japanese team and designated TT virus (TTV). This virus seemed to be associated with non-A, non-G post-transfusion hepatitis. It was isolated by polymerase chain reaction (PCR) and was presumed to be human Circoviridae. The virus is heterogenous; 16 different genotypes are currently registered, and it can be classified as a "swarm" of at least 5 different viruses. Depending on the PCR technique used, the prevalence of infection ranges from 1.9 to 36% among blood donors, from 11.5 to 71% in hemodialysis patients, from 47 to 82% among patients with non-A, non-B or non-C fulminant hepatic failure, and the most elevated percentage is found in hemophiliacs. Epidemiological studies have established that the routes of TTV infection might be parenteral, oral-fecal, and possibly salivary. Mother-to-infant transmission is controversial. TTV may play a role in the pathogenesis of non-A, non-B or non-C fulminant hepatic failure. Patients co-infected with hepatitis C virus (HCV) and TTV have a significantly higher histological grade score than patients with isolated HCV infection. Treatment with interferon seems to decrease TT viremia, according to results obtained outside the context of clinical trials. TTV seems to be a light pathogenic virus. Its widespread presence in the blood of infected subjects contrasts with the apparent absence of pathological symptoms. PCR standardization is needed to clearly establish its real prevalence worldwide.

The prevalence of TT virus (TTV) infection was investigated by Polymerase Chain Reaction (PCR) in low- (blood donors and healthy children/adolescents) and high-risk (hemophiliacs) groups from São Paulo, Brazil. Primers based on the untranslated region (UTR) of the viral genome proved to be much more ubiquitous, leading to much higher frequencies for both groups (>or= 81%) than the earlier N22-PCR directed to the open reading frame 1 (blood donors, 5.5%, and hemophiliacs, 42.3%). The UTR-PCR also revealed an interesting profile for healthy children/adolescents: very high prevalence at the early years and significant decrease in male teenagers. The N22-PCR, in turn, demonstrated higher frequency in hemophiliacs treated with fresh blood products (58%), than in those treated with virus-inactivated clotting factors (9.4%) and blood donors (5.5%).

Recombinant plasmids carrying 199 base pairs (bp) inserts from the non coding region (nucleotides (nt) 6-204) of the TT virus (TTV) genome were used to standardize an heteroduplex mobility assay able to detect mixed infections of a single individual with several TTV isolates. In this simplified heteroduplex mobility assay, polymerase chain reaction (PCR) products were analyzed directly by polyacrylamide gel electrophoresis, without requirement for post-PCR denaturation and annealing steps of the amplicons. The assay was used to test TTV positive serum samples collected from healthy 1-7 years old children, 11-17 years old adolescents, and 24-39 years old blood donors living in Rio de Janeiro, Brazil, as well as TTV positive samples from Amazonian Indians. The results showed a very high frequency of multiple infection in all groups, with 20/30 (67%), 31/33 (94%), 35/38 (92%), and 34/37 (92%) of the samples collected from children, adolescents, blood donors, and Amazonian Indians, respectively, containing more than one TTV genotype.

Characterization of TT virus (TTV), the history of its discovery, taxonomy and identification are reviewed as update on the diagnostics of TTV infection with PCR. The variability of the virus and resulting difficulties in the selection of a TTV DNA fragment for amplification are described. Data on the virus prevalence, replication and persistence are given. The pathogenetic importance of TTV is discussed with the account of different concepts.

The possible causative role of novel TT virus in liver diseases has been intensively studied in regarding its hepatotrophy, ability to cause persistent infection and worldwide prevalence. The aim of this study was to estimate the prevalence as well as the clinical importance of TTV in a normal healthy population group in the Czech Republic and in a group of liver transplant recipients diagnosed with cryptogenic cirrhosis. Polymerase chain reaction (PCR) detected the DNA of TT virus in 68% (13/19) of samples isolated from peripheral blood leukocytes and in 21% (4/19) of plasma samples in the liver transplant group. The viral DNA was detected only in 11.8% (4/34) of leukocytes and in no plasma sample from the healthy population control group. All patients included in this study had good liver function and had no complications during the postoperative period. The prevalence of TTV DNA detection in healthy control group in Czech republic is similar to the rates reported in European and North American countries. Significant difference was proved between the prevalences of TTV in the groups of healthy controls and liver transplant recipients with cryptogenic cirrhosis. However, no association of TTV infection with possible postoperative complications could be found.

Skin lesions are prominent features of many viral diseases. In some instances, characteristic skin lesions suggest a specific viral illness, the diagnosis of which can be quickly established by appropriate procedures. In addition to clinical manifestations, laboratory methods including virus isolation are used to diagnose viral infections. In viral diseases, prophylaxis has proved more successful than the specific treatment of established infection. However, recent progress in molecular biology has facilitated the development of new vaccines and new drugs to treat viral infections.

Recent discovery of a novel DNA virus from the serum of a Japanese patient (T.T.) has prompted further studies directed on possible role of TT virus in the development of cryptogenic hepatitis. The TT is an unenveloped and circular DNA virus. TTV possesses single stranded DNA genome and comprises 3537 to 3853 nucleotides. TTV is similar to the Circoviridae and possesses three open reading frames. Phylogenetic analysis revealed up to 30% nucleotide sequence divergence in the 16 virus genotypes. TTV infection can be detected by polymerase chain reactions, in situ hybridization and by specific antibodies to TTV. TTV DNA has been identified in the serum of patients with cryptogenic hepatitis, hepatitis B and C, hepatocellular carcinoma as well as in healthy individuals. TTV has been found also in the peripheral blood leukocytes, bone marrow cells, liver biopsies as well as in feces and breast milk. Some animals including cattle, sheep, pigs and chicken appeared to have TTV viremia. Recent detection of TTV in nonblood products, such as saliva and feces suggest in addition to parenteral also nonparenteral routes of TTV transmissions including sexual and fecal-oral.

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.

To evaluate the molecular epidemiology and clinical significance of th

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.

A 10-year-old girl with thalassemia underwent bone marrow transplantation. Before transplantation, she had persistent TT virus (TTV) DNAemia for at least 18 months. Interestingly, the viral DNAemia was cleared soon after transplant and remained undetectable at the latest follow-up at 28 months. The early clearance of TTV that had occurred before engraftment or initiation of any antiviral therapy, together with the absence of TTV DNA from the results of the liver biopsy performed before transplantation, led us to hypothesize that the hematologic compartment could have been the site for viral persistence. Thus, the conditioning regimen may have depleted the hemic cells and the hematologically compartmentalized TTV. The potential of hemic tropism of TTV and its role in hematologic diseases need to be considered.

TT virus (TTV) was first described in 1997 by representational difference analysis of sera from non-A to non-G posttransfusion hepatitis patients and hence intensively investigated as a possible addition to the list of hepatitis-inducing viruses. The TTV genome is a covalently closed single-stranded DNA of approximately 3.8 kb with a number of characteristics typical of animal circoviruses, especially the chicken anemia virus. TTV is genetically highly heterogeneous, which has led investigators to group isolates into numerous genotypes and subtypes and has limited the sensitivity of many PCR assays used for virus detection. The most remarkable feature of TTV is the extraordinarily high prevalence of chronic viremia in apparently healthy people, up to nearly 100% in some countries. The original hypothesis that it might be an important cause of cryptogenic hepatitis has not been borne out, although the possibility that it may produce liver damage under specific circumstances has not been excluded. The virus has not yet been etiologically linked to any other human disease. Thus, TTV should be considered an orphan virus.

TT virus (TTV) has not yet been cultured or visualized. We attempted to recover and visualize TTV-associated particles from the serum samples and feces of infected humans. Serum samples were obtained from 7 human immunodeficiency virus (HIV)-infected patients. Three patients had a high TTV DNA titer (10(8) copies/ml), three had a low TTV DNA titer (10(2) copies/ml), and one was negative for TTV DNA. Fecal supernatant was obtained from a different TTV-infected subject. The serum samples were fractionated by high-performance liquid chromatography, and TTV DNA-rich fractions were subjected to floatation ultracentrifugation in cesium chloride. Virus-like particles, 30-32 nm in diameter, were found in the 1.31-1.33 g/cm(3) fractions from each of the three serum samples with high TTV DNA titer, but not in any fraction from the four serum samples that either were negative for TTV DNA or had low TTV DNA titer. The TTV particles formed aggregates of various sizes, and immunogold electron microscopy showed that they were bound to human immunoglobulin G. Similar virus-like particles with a diameter of 30-32 nm banding at 1.34-1.35 g/cm(3) were visualized in fecal supernatant with TTV genotype 1a by immune electron microscopy using human plasma containing TTV genotype 1a-specific antibody., (Copyright 2000 Academic Press.)

Objective: Recently, a novel DNA virus (TT virus; TTV) has been isolated. Enteric transmission is suggested as a route of transmission of TTV, with high prevalence of this virus infection in the general population, and age and geographical distributions of TTV prevalence very similar to those of Helicobacterpylori infection. We analysed an association between TTV and H. pylori infection in patients with gastroduodenal ulcer or ulcer scar., Methods: In 181 patients with a gastroduodenal ulcer or ulcer scar (102 with a gastric lesion, 60 with a duodenal lesion, and 19 with both sites involved), specimens were cultured for H. pylori and TTV infection was sought in serum by a polymerase chain reaction., Results: H. pylori infection was demonstrated in 152 patients (84.0%) and TTV was detected in 168 patients (92.8%). Patients with TTV were significantly older than those without TTV (P = 0.0001), while no age difference was observed between patients with and without H. pylori infection. No difference was apparent in the prevalence of TTV infection between patients with and without H. pylori infection, and vice versa., Conclusions: We found no association between TTV infection and H. pylori infection in patients with peptic ulcer diseases, which is consistent with a lack of association between TTV infection and peptic ulcer. However, larger studies including surveys of the general population will be required to analyse the overall association between TTV and H. pylori.

Background: The recent discovery of a new parenterally transmitted DNA virus called TT virus (TTV) led us to investigate its prevalence in haemodialysis patients, a high-risk group for blood-borne infection, and to evaluate its role in liver disease. Moreover, we compared the TTV prevalence with the prevalence of other hepatitis virus coinfections., Methods: Serum samples of 78 patients on maintenance haemodialysis were tested for TTV-DNA, hepatitis G virus (HGV)-RNA, anti-E2, anti-hepatitis C virus (HCV) and HCV-RNA. TTV-DNA was detected by semi-nested PCR using the primers from open reading frame 1 (ORF). HGV-RNA was detected by PCR using specific primers for the NS3 and the 5'-UTR genome regions while anti-E2 were checked by an enzyme immunological test. Anti-HCV was tested by the second generation Chiron RIBA HCV test system. HCV-RNA was evaluated by nested PCR with primers directed to the highly conserved 5' non-coding region of the HCV genome., Results: TTV prevalence in our patients was 19% (15/78) while the prevalence of HCV and HGV infection proved to be 20 and 15.4%, respectively. Among TTV positive patients HGV co-infection was present in five cases (33%), HCV in six cases (39.9%), while HBV co-infection was not present in any of the patients. Only three patients proved positive for all three viruses. ALT levels were normal in most cases (13/15; 86%). In particular, patients with TTV infection alone showed normal ALT levels and HCV coinfection was found in the two patients with moderate ALT increases., Conclusions: TTV prevalence in haemodialysed patients is significant though the real clinical impact is still unclear. However, we must keep in mind that the epidemiological relevance of TTV infection is probably underestimated due to the impossibility in detecting the corresponding antibody.

Background: The TT virus (TTV) is a newly identified human DNA virus and little is known about its non-parenteral transmission. The aim of the present study was to explore the prevalence of TTV infection in spouses of index cases and the related risk factors., Methods: Serum TTV-DNA was studied in spouses of 41 subjects with TT viremia. For couples in which both husband and wife had TT viremia, nucleotide sequences of the open reading frame-1 region were analyzed by phylogenetic tree constructions., Results: Three (7%) of 41 spouses were positive for TTV-DNA. No differences were noted between index patients with seropositive spouses and those without seropositive spouses with regard to clinical characteristics, including parenteral risk factors and exposure duration. Nucleotide sequence comparison and phylogenetic tree analysis of the viral genome in three TTV-infected couples revealed the isolates to be closely related in two, with a homology of 97 and 98%, respectively., Conclusions: These results suggest that interspousal transmission of TTV does occur; however,the efficiency of transmission is low compared with hepatitis C virus and GB virus-C. There are no apparent risk factors for transmission between spouses and further studies are needed to clarify other modes of non-parenteral transmission.

A new approach for an internally controlled PCR was developed using a custom-synthesized oligonucleotide as the internal control. Three different PCR setups demonstrated the usefulness of this approach: (i) the addition of the respective internal control to samples containing ssDNA virus Parvo B19; (ii) the co-extraction of plasma samples and the respective internal control for the detection of the ssDNA virus TTV; and (iii) the addition of the respective internal control to a crude lysate of tail pieces for the genotyping of FVIII knockout mice, demonstrating that this approach is also applicable for dsDNA.

Although TT virus (TTV) was isolated from a cryptogenic posttransfusion hepatitis patient, its pathogenic role remains unclear. It has been reported that the majority of the healthy population is infected with TTV. To elucidate the differences between TTV infection in patients with liver diseases and TTV infection in the healthy population, a quantification system was developed. TTV DNA was quantified by a real-time detection PCR (RTD-PCR) assay on an ABI Prism 7700 sequence detector. With this system, TTV DNA was quantified in 78 hepatitis C virus (HCV)-infected patients (63 with elevated serum alanine aminotransferase [ALT] levels and 15 with normal ALT levels) and in 70 voluntary blood donors (BDs). The quantification range was 2.08 to 7.35 log copies/ml. The intra-assay and interassay coefficients of variation were 0.37 to 6.33% and 0.60 to 7.07%, respectively. The mean serum TTV DNA levels in the HCV-infected patients with both elevated and normal ALT levels and BDs were 3.69 +/- 0.89, 3.45 +/- 0.76, and 3.45 +/- 0.67 log copies/ml, respectively. Comparison of the serum TTV DNA levels among the HCV-infected patients revealed that they were not related to the serum ALT and HCV core protein levels or to the histopathological score on liver biopsy. This study showed that (i) the RTD-PCR assay for the detection of TTV was accurate and had a high degree of sensitivity, (ii) the mean serum TTV DNA level was similar among HCV-infected patients, irrespective of their ALT level, and also among BDs, and (iii) a high serum TTV DNA level does not affect the serum ALT and HCV levels or liver damage in HCV-infected patients.

Aim: To examine clinical, immunological and morphological features of HGV- and TTV-infections in patients with chronic hepatic diseases (CHD) and assess efficiency of treatment of HGV-seropositive patients., Material and Methods: 202 patients with CHD were examined for markers of HBV-, HCV-, HGV- and TTV-infections. Some patients were subjected to puncture biopsy of the liver. Efficiency of interferon-alpha treatment of HGV and HBV/HCV coinfection was studied., Results: HGV RNA and TTV DNA were detected in 19.8 and 11.8% of cases, respectively. Biochemical indices in patients with HGV and TTV monoinfections significantly differed from those in the control group while morphological changes in most of them corresponded to those with hepatitis. INF-alpha was given to 7 patients with HGV + HBV/HCV infections. A response was achieved in 3 months in 2 of them., Conclusion: The role of HGV and TTV in hepatic diseases pathology is still unclear. Further studies on detection and examination of patients infected with G and TT viruses are necessary. When choosing therapy, the presence of HGV RNA and TTV DNA in blood serum, virus genome in hepatocytes and histological changes in hepatic tissue should be considered.

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.

A polymerase chain reaction (PCR)-based procedure for the detection of TT virus DNA is described. In this method. total nucleic acid extracted from a small volume of serum or plasma is utilized as a template in PCR employing TT virus specific primers designed to highly conserved regions of the virus genome. Additional sensitivity is obtained by carrying out a second round of amplification. Reactions are analyzed by agarose gel electrophoresis, and samples having an ethidium bromide stainable fragment of the appropriate size in the first and/or second amplification are designated as positive. This protocol allows for the rapid and sensitive detection of TT virus in human plasma or serum.

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.