High prevalence of TT virus infection in French blood donors revealed by the use of three PCR systems

Torque Teno Virus load in lung cancer patients correlates with age but not with tumor stage

Background

Torque teno virus (TTV) is a ubiquitous non-pathogenic virus, which is suppressed in immunological healthy individuals but replicates in immune compromised patients. Thus, TTV load is a suitable biomarker for monitoring the immunosuppression also in lung transplant recipients. Since little is known about the changes of TTV load in lung cancer patients, we analyzed TTV plasma DNA levels in lung cancer patients and its perioperative changes after lung cancer surgery.

Material and methods

Patients with lung cancer and non-malignant nodules as control group were included prospectively. TTV DNA levels were measured by quantiative PCR using DNA isolated from patients plasma and correlated with routine circulating biomarkers and clinicopathological variables.

Results

47 patients (early stage lung cancer n = 30, stage IV lung cancer n = 10, non-malignant nodules n = 7) were included. TTV DNA levels were not detected in seven patients (15%). There was no significant difference between the stage IV cases and the preoperative TTV plasma DNA levels in patients with early stage lung cancer or non-malignant nodules (p = 0.627). While gender, tumor stage and tumor histology showed no correlation with TTV load patients below 65 years of age had a significantly lower TTV load then older patients (p = 0.022). Regarding routine blood based biomarkers, LDH activity was significantly higher in patients with stage IV lung cancer (p = 0.043), however, TTV load showed no correlation with LDH activity, albumin, hemoglobin, CRP or WBC. Comparing the preoperative, postoperative and discharge day TTV load, no unequivocal pattern in the kinetics were.

Conclusion

Our study suggest that lung cancer has no stage dependent impact on TTV plasma DNA levels and confirms that elderly patients have a significantly higher TTV load. Furthermore, we found no uniform perioperative changes during early stage lung cancer resection on plasma TTV DNA levels.

Assessment of prevalence and load of torquetenovirus viraemia in a large cohort of healthy blood donors

OBJECTIVES

Torquetenovirus (TTV) is an emerging marker of functional immune competence with the potential to predict transplant-related adverse events. A large-scale epidemiological study was performed to understand how basal values vary in healthy individuals according to age and gender.

METHODS

We tested plasma from 1017 healthy blood donors aged 18-69 years. The presence and load of TTV were determined by a real-time PCR assay. A sub-cohort of 384 donors was tested for anti-cytomegalovirus IgG antibodies, and 100 participants were also tested for TTV viraemia on a paired whole blood sample.

RESULTS

The overall prevalence of TTV was 65% (657/1017) with a mean (±SD) growth of 5 ± 4% every 10 years of age increase, but stably higher in males (465/690, 67%) than in females (192/327, 59%). Mean (±SD) TTV load was 2.3 ± 0.7 Log copies/mL with no sex difference. TTV viraemia showed modest increases along 10-year age intervals (mean ± SD: 0.3 ± 0.1). TTV viraemia in donors sampled 2 years later remained stable (mean ± SD: 2.3 ± 0.8 versus 2.2 ± 0.7 Log copies between samples). Twenty-six per cent (9/34) of blood donors with TTV-negative plasma scored positive when whole blood was tested, and the donors with positive plasma showed a mean (±SD) 1.4 ± 0.5 Log increase in copy numbers when whole blood was tested.

CONCLUSIONS

This study establishes the mean value of TTV viraemia in plasma in healthy blood donors and suggests that ageing causes only minimal increases in TTV viraemia.

Monitoring of alphatorquevirus DNA levels for the prediction of immunosuppression-related complications after kidney transplantation

The replication kinetics of nonpathogenic anelloviruses belonging to the Alphatorquevirus genus (such as torque teno virus) might reflect the overall state of posttransplant immunosuppression. We analyzed 221 kidney transplant (KT) recipients in whom plasma alphatorquevirus DNA load was quantified by real-time polymerase chain reaction at baseline and regularly through the first 12 posttransplant months. Study outcomes included posttransplant infection and a composite of opportunistic infection and/or de novo malignancy (immunosuppression-related adverse event [iRAE]). Alphatorquevirus DNA loads at month 1 were higher among patients who subsequently developed posttransplant infection (P  = .023) or iRAE (P  = .009). Likewise, those with iRAE beyond months 3 and 6 also exhibited higher peak viral loads over the preceding periods. Areas under the curve for log₁₀ alphatorquevirus DNAemia estimated by months 1 or 6 were significantly higher in patients experiencing study outcomes. Alphatorquevirus DNA loads above 3.15 and 4.56 log₁₀ copies/mL at month 1 predicted the occurrence of posttransplant infection (adjusted hazard ratio [aHR]: 2.88; 95% confidence interval [CI]: 1.13-7.36; P  = .027) and iRAE (aHR: 5.17; 95% CI: 2.01-13.33; P  = .001). In conclusion, posttransplant monitoring of plasma alphatorquevirus DNA kinetics may be useful to identify KT recipients at increased risk of immunosuppression-related complications.

Global occurrence of Torque teno virus in water systems

Bacterial indicator organisms are used globally to assess the microbiological safety of waters. However, waterborne viral outbreaks have occurred in drinking water systems despite negative bacterial results. Using viral markers may therefore provide more accurate health risk assessment data. In this study, fecal, wastewater, stormwater, surface water (fresh and salt), groundwater, and drinking water samples were analyzed for the presence or concentration of traditional indicators, innovative indicators and viral markers. Samples were obtained in the United States, Italy, and Australia and results compared to those reported for studies conducted in Asia and South America as well. Indicators included total coliforms, Escherichia coli, enterococci, male-specific coliphages, somatic coliphages and microviradae. Viral markers included adenovirus, polyomavirus, and a potential new surrogate, Torque teno virus (TTV). TTV was more frequently found in wastewaters (38-100%) and waters influenced by waste discharges (25%) than in surface waters used as drinking water sources (5%). TTV was also specific to human rather than animal feces. While TTV numbers were strongly correlated to other viral markers in wastewaters, suggesting its utility as a fecal contamination marker, data limitations and TTV presence in treated drinking waters demonstrates that additional research is needed on this potential viral indicator.

Describing the silent human virome with an emphasis on giant viruses

Viruses are the most abundant obligate intracellular entities in our body. Until recently, they were only considered to be pathogens that caused a broad array of pathologies, ranging from mild disease to deaths in the most severe cases. However, recent advances in unbiased mass sequencing techniques as well as increasing epidemiological evidence have indicated that the human body is home to diverse viral species under non-pathological conditions. Despite these studies, the description of the presumably healthy viral flora, i.e. the normal human virome, is still in its infancy regarding viral composition and dynamics. This review summarizes our current knowledge of the human virome under non-pathological conditions.

Virus contaminations of cell cultures - A biotechnological view

In contrast to contamination by microbes and mycoplasma, which can be relatively easily detected, viral contamination present a serious threat because of the difficulty in detecting some viruses and the lack of effective methods of treating infected cell cultures. While some viruses are capable of causing morphological changes to infected cells (e.g. cytopathic effect) which are detectable by microscopy some viral contaminations result in the integration of the viral genome as provirus, this causes no visual evidence, by means of modification of the cellular morphology. Virus production from such cell lines, are potentially dangerous for other cell cultures (in research labs)by cross contaminations, or for operators and patients (in the case of the production of injectable biologicals) because of potential infection. The only way to keep cell cultures for research, development, and the biotech industry virus-free is the prevention of such contaminations. Cell cultures can become contaminated by the following means: firstly, they may already be contaminated as primary cultures (because the source of the cells was already infected), secondly, they were contaminated due to the use of contaminated raw materials, or thirdly, they were contaminated via an animal passage. This overview describes the problems and risks associated with viral contaminations in animal cell culture, describes the origins of these contaminations as well as the most important virsuses associated with viral contaminations in cell culture. In addition, ways to prevent viral contaminations as well as measures undertaken to avoid and assess risks for viral contaminations as performed in the biotech industry are briefly described.

Association of torque teno virus (TTV) and torque teno mini virus (TTMV) with liver disease among patients coinfected with human immunodeficiency virus and hepatitis C virus

Torque teno virus (TTV) and torque teno mini virus (TTMV) have been potentially related to liver diseases. The aim of the study was to quantify TTV and TTMV in human immunodeficiency virus (HIV)/hepatitis C virus (HCV)-coinfected patients to study the relationship between the TTV and TTMV viral loads and the severity of liver disease. We carried out a cross-sectional study in 245 patients coinfected with HIV and HCV (HIV/HCV-group), 114 patients monoinfected with HIV (HIV-group), and 100 healthy blood donors (Control-group). Plasma samples were tested for TTV and TTMV by quantitative real-time polymerase chain reaction (PCR). The prevalences of TTV and TTMV infections in the HIV/HCV-group and the HIV-group were significantly higher than the Control-group (p < 0.05). Furthermore, TTV and TTMV coinfections were found in 92.2 % (226/245) in the HIV/HCV-group, 84.2 % (96/114) in the HIV-group, and 63 % (63/100 %) in the Control-group (p ≤ 0.05). HIV/HCV-coinfected patients with HIV viral load ≥50 copies/mL and patients with severe activity grade had the highest viral loads of TTV and TTMV (p ≤ 0.05). HIV/HCV-coinfected patients with high TTV load (>2.78 log copies/μL) had increased odds of having advanced fibrosis or severe necroinflammatory activity grade in the liver biopsy. Moreover, HIV/HCV-coinfected patients with high TTMV load (>1.88 log copies/μL) had decreased odds of having no/minimal fibrosis and no/mild activity grade, and increased odds of having a high fibrosis progression rate. In conclusion, TTV and TTMV might play a role in the development of liver disease in immunodeficiency patients, such as the patients coinfected with HIV and HCV.

Detection of TT virus by single-primer sequence-independent amplification in multiple samples collected from an outbreak of gastroenteritis

A panel of gastroenteritis outbreak samples was subjected to a virus purification and concentration algorithm followed by a sequence-independent amplification method devised to detect viral enteric pathogens. The application of these methods allowed the identification of torque teno virus (TTV) in one outbreak. The complete genome sequence of 3,260 nt was obtained through "genome walking", and four open reading frames were deduced from the genomic sequence. Phylogenetic analysis grouped this virus in TTV genetic group 3, clustering with genotype 27, with 85% similarity at the nt level with strain SAa-01.

Torque Teno Virus: any pathological role in liver transplanted patients?

Few studies have been performed on the prevalence of Torque Teno Virus (TTV) infection in liver transplant (LT) recipients. The aim of this study was to assess the prevalence, viremia and genogroup pattern of TTV among LT patients and to ascertain whether TTV causes liver damage in liver transplanted patients with biochemical and histological changes of unknown origin. Twenty-five patients were evaluated before and after LT; 80 healthy subjects were considered as controls. Serum samples were serially obtained from all the patients before LT and thereafter at 3, 6 and 12 months post-transplant. Serum TTV-DNA and genogroups were assessed by PCR. Patients underwent protocol serial liver biopsies at 6 and 12 months after LT. Results were compared using the Chi-squared tests, McNemar's and Student's t-tests. TTV-DNA was found in 25/25 patients before LT and in 60/80 blood donors (P < 0.01). The TTV-DNA load increased significantly after LT (P < 0.001). TTV-DNA was significantly higher in patients on calcineurin inhibitors (CNI) and azathioprine or mycophenolate mofetil than in patients on CNI alone (P = 0.04) at 3 months after LT. Genogroup analysis showed a significant increase in genogroup 5 positivity after LT. No differences were seen in the viremia of patients compared according to their viral versus other etiologies of their liver disease before transplantation. Viremia and TTV genotype patterns did not correlate with the presence of hypertransaminasemia or histological liver damage of unknown etiology. The prevalence of TTV-DNA was significantly higher in patients with liver cirrhosis than in controls and the viral load was significantly higher after LT than beforehand. On the basis of our data, TTV does not seem to cause liver damage following LT, although larger studies with a long-term follow up are needed to confirm these findings.

Development of PCR assays with nested primers specific for differential detection of three human anelloviruses and early acquisition of dual or triple infection during infancy

We recently identified a novel human virus classifiable into a third group in the genus Anellovirus, tentatively designated torque teno midi virus (TTMDV), with a circular DNA genome of 3.2 kb and genomic organization resembling those of torque teno virus (TTV) (3.8 to 3.9 kb) and torque teno mini virus (TTMV) (2.8 to 2.9 kb). TTMDV was characterized by extreme genetic diversity similar to the TTV and TTMV genomes. Taking advantage of universal and virus species-specific primers derived from a highly conserved area located just downstream of the TATA box of the TTV, TTMDV, and TTMV genomes, a PCR method with simultaneous amplification of the genomic DNAs of these three anelloviruses in the first round and subsequent differential amplifications of these viruses in the second round was developed. High prevalence of TTMDV viremia was seen in adults (75/100 [75%]), comparable with the prevalences of TTV viremia (100%) and TTMV viremia (82%). Although none of 10 cord blood samples had detectable TTV, TTMDV, and TTMV DNAs, the prevalences of these three anelloviruses increased with the number of months after birth of the individual and reached 100% for individuals at one year of age. Dual or triple infection of TTV, TTMDV, and/or TTMV was seen in 10 (47.6%) of 21 infants 9 to 180 days of age and more frequently among infants 181 to 364 days of age (20/23 [86.9%]), comparable with the 93.1% (243/261) prevalence among subjects 1 to 81 years of age, indicating early acquisition of dual or triple anellovirus infection during infancy.

Performance of three PCR methods targeting different regions of viral genome for the detection of TTV in Non A-E hepatitis, chronic B and C hepatitis and healthy blood donors

TT virus (TTV) was suggested to be the etiologic agent for non A-E hepatitis but this could not yet be proven due to high detection rates not only in hepatitis but also in healthy persons and sensitivity differences of PCR methods employed. The aim of this study was to evaluate TTV DNA positivity in non A-E hepatitis cases, chronic HBV and HCV hepatitis cases and healthy blood donors via PCR systems that target all regions of the viral genome used for viral detection. 23 non A-E hepatitis, 28 chronic HCV, 21 chronic HBV cases and 56 healthy blood donors were included in the study and evaluated by PCR protocols that target 5′-UTR, 3′-UTR and N22 (ORF1) regions. As a result, 3′-UTR and 5′-UTR PCR had comparable detection rates that were higher than N22 PCR. Differences in detection rates among study groups were not statistically significant for any PCR method. Hepatic enzyme levels of the patients were not correlated with the presence of TTV DNA. Detection rate was significantly higher for Non A-E hepatitis group when positivity rates from all methods were combined. These results suggest an alteration of viral genotypes in Non A-E hepatitis which might be associated with pathogenesis.

Transfusion-transmitted virus prevalence in Turkish patients with thalassemia

In hematology patients on chronic transfusion regimes, liver diseases are frequent, and mostly related to the agents transmitted by blood products and concominant iron deposition in liver. Besides hepatitis B (HBV) and C (HCV) viruses, new viral agents like hepatitis G virus (HGV) and TorqueTeno virus (TTV) are identified in these patients, although their association with any pathology or disease is not yet proved. In the present work, the authors studied the clinical importance of TTV in Turkish multitransfused patients with thalassemia. Forty-six healthy and 57 thalassemic patients were enrolled in the study. TTV was detected in serum samples by 3'-UTR nested PCR. Transaminase and ferritin levels, hepatitis B and C virus markers and number of transfusions were interpreted for possible association with TTV infection. As a result, TTV was detected in 63% of the thalassemia and 54% of the control patients. Prevalence of TTV infection, clinical features, laboratory data, and annual transfusion numbers of TTV-positive and -negative patients were not observed to be statistically significant. In conclusion, in Turkish patients with thalassemia, TTV infection cannot be considered as a risk factor for liver disease.

Relationships between total plasma load of torquetenovirus (TTV) and TTV genogroups carried

In 239 torquetenovirus-positive people, multiple-genogroup infections were common and associated with higher viral loads than would be expected from simple additive effects. The latter observation was restricted to the infections which included both genogroups 1 and 3, pointing to the possible existence of some kind of infection facilitation between these genogroups.

A multiplex PCR assay able to simultaneously detect Torque teno virus isolates from phylogenetic groups 1 to 5

Torque teno virus (TTV) is a circular, single-stranded DNA virus that chronically infects healthy individuals of all ages worldwide. TTV has an extreme genetic heterogeneity which is reflected in its current classification into five main phylogenetic groups (1-5). Using specific PCR assays, it has been shown that many individuals are co-infected with TTV isolates belonging to different phylogenetic groups. Here, a multiplex PCR assay was developed, using five recombinant plasmids. Each plasmid carried an insert of different size issued from a TTV isolate belonging to a different group. The assay was able to simultaneously amplify DNAs of TTV isolates belonging to all five phylogenetic groups. Multiplex PCR was then tested satisfactorily on DNAs extracted from 55 serum samples (47 health care workers and 8 AIDS patients). All individuals but nine were infected with at least one TTV isolate. Co-infection with multiple isolates was found in 29/47 (62%) health care workers and in 8/8 (100%) AIDS patients. A number of discrepancies were observed when results obtained with three thermostable DNA polymerases were compared. For example, four TTV phylogenetic groups were detected in a particular serum sample by using one of the three DNA polymerases, whereas the other two enzymes were able to detect only three TTV groups. However, none of the three enzymes used could be broadly considered to be more efficient than the others. Despite its limitations, the assay described here constitutes a suitable tool to visualize the degree of co-infection of a given population, avoiding time-consuming experiments.

Distribution and genetic analysis of TTV and TTMV major phylogenetic groups in French blood donors

TTV and TTMV (recently assigned to the floating genus Anellovirus) infect human populations (including healthy individuals) at high prevalence (>80%). They display notably high levels of genetic diversity, but very little is known regarding the distribution of Anellovirus genetic groups in human populations. We analyzed the distribution of the major genetic groups of TTV and TTMV in healthy voluntary blood donors using group-independent and group-specific PCR amplifications systems, combined with sequence determination and phylogenetic analysis. Analysis of Anellovirus groups revealed a non-random pattern of group distribution with a predominant prevalence of TTV phylogenetic groups 1, 3, and 5, and of TTMV group 1. Multiple co-infections were observed. In addition, TTMV sequences exhibiting a high genetic divergence with reference sequences were identified. This study provided the first picture of the genetic distribution of the major phylogenetic groups of members of the genus Anellovirus in a cohort of French voluntary blood donors. Obtaining such data from a reference population comprising healthy individuals was an essential step that will allow the subsequent comparative analysis of cohorts including patients with well-characterized diseases, in order to identify any possible relationship between Anellovirus infection and human diseases.

Prevalence and partial characterization of genotypes of the human TT virus infecting Portuguese individuals

The prevalence and genotype distribution of human TT viruses (TTV) were analyzed in 312 Portuguese individuals. Detection of TTV DNA was carried out by polymerase chain reaction (PCR) through the combined use of N22 and UTR-specific primers and revealed a prevalence of infection of 74%. Detection of TTV DNA was not statistically associated to the use of intravenous drugs, infection with HBV, HCV, HIV-1, HIV-1 viral load or CD4 cell count (in HIV-1 infected individuals). Our data suggest that, in the population studied, the prevalence of TTV infection does not seem to be related to intravenous viral transmission. Phylogenetic analysis of 49 plasmid clones harboring N22-specific sequences revealed the circulation of genotypes: 1 (27%, subtype G1a and G1b), 2 (51%, subtype G2b and G2c) and 4 (22%), as well as multiple genotype infections (G1b-G2b and G1a-G4). To our knowledge, this is the first report of TTV detection and partial characterization of TTV genetic variants in Portuguese individuals. Our results show that TTV infection is widespread in Portugal as in other parts of the world.

Human circoviruses

TT virus (TTV) and TTV-like mini virus (TLMV) represent the first described human circoviruses. They do not show significant sequence homology with any other animal circovirus identified to date. They are both detected with high prevalences in various body fluids. The spread mode may include the parenteral way, the transmission by saliva droplets and the fecal-oral route. Genetic variability within a viral group is high and the co-infection by distinct viral strains is common in a given individual. The description of several messenger RNAs obtained after multiple splicing revealed a specific transcription profile. Despite apparent asymptomatic infections, the possible association of variants of TTV and TLMV with a given pathology cannot be formally ruled out.

High prevalence of transfusion-transmitted virus infection in patients with chronic liver diseases in an endemic area of hepatitis B and C virus

OBJECTIVE

To determine the prevalence and clinical impact of transfusion-transmitted virus (TTV) DNA in patients with chronic liver diseases in the Southeast Anatolia region of Turkey where hepatitis B and C viral infections are endemic.

SUBJECTS AND METHODS

Patients diagnosed with chronic liver disease by clinical, biochemical and histologic means were enrolled in the study. Serum samples of 60 patients (19 males, 41 females) with chronic liver diseases, and of 45 healthy volunteer blood donors as a control group were collected. The chronic liver disease group consisted of 11 patients with hepatitis B, 44 with hepatitis C and 5 with chronic liver disease of unknown etiology. Presence of TTV DNA was investigated by the polymerase chain reaction. Using a scoring system histological grading of inflammation and staging of fibrosis were performed only in the chronic hepatitis C group.

RESULTS

TTV DNA was detected in 47 (78%) patients with chronic liver disease and 5 (11%) volunteers in the control group. The difference was statistically significant (p < 0.001). Ten of the 11 (91%) patients with hepatitis B, 32 of 44 (73%) of those with hepatitis C-related chronic liver disease, and 5 of 5 (100%) of the patients with cryptogenic liver disease were positive for TTV DNA.

CONCLUSION

TTV is highly prevalent in patients with chronic liver diseases in Southeast Anatolia, Turkey but no pathogenic effect attributable to TTV infection was detected.

Distribution of TT virus genomic groups 1-5 in Brazilian blood donors, HBV carriers, and HIV-1-infected patients

Human isolates of the highly prevalent TT virus (TTV) have been classified into five major genomic groups (1-5). The geographical distribution of the groups throughout the world is not well known. Five different PCR assays were developed in an attempt to amplify specifically TTV DNAs of each genomic group. Serum samples collected from 72 Brazilian adults (24 voluntary blood donors, 24 hepatitis B virus (HBV) carriers, and 24 human immunodeficiency virus type 1 (HIV-1)-infected patients) were tested. TTV DNA from at least one genomic group was detected in 11 (46%) blood donors, 13 (54%) HBV carriers, and 24 (100%) HIV-1 patients. All five genomic groups were detected in the three populations, with the exception of group 2 in blood donors. Some samples, negative with all five specific assays, were positive with the commonly used untranslated region (UTR) PCR system. On the other hand, TTV DNA was detected in some samples by using specific assays but not with the UTR PCR. Mixed infections with 2-5 TTV isolates from different groups were detected in 21% blood donors, 29% HBV carriers, and 71% HIV-1 patients. Fifteen PCR products (three obtained with each assay) were sequenced. Most sequences showed high (>86%) homology with those of TTV isolates belonging to their presumed groups. However, three sequences had low homology with all TTV sequences available from the DNA databanks. In conclusion, TTV isolates belonging to all five known genomic groups circulate in Brazil, and the results suggest the existence of new and as yet uncharacterised major genomic groups.

High genetic diversity revealed by the study of TLMV infection in French hemodialysis patients

TT virus-like minivirus (TLMV) was recently discovered as a human circovirus. Little is known about its natural history and molecular epidemiology. A study of TLMV infection is described in a population of French hemodialysis patients. TLMV DNA was tested by seminested PCR system located in the noncoding region in 81 patients divided into seven groups according to the origin of their renal disease. Quantitation of TLMV DNA in serum was carried out. Sequences from 28 patients were compared with 40 sequences retrieved from databases and 53 TLMV sequences cloned from the serum of a single patient. The prevalence of TLMV DNA in hemodialysis patients was 95.1%. In this study, 24 samples (29.6%) presented viral loads of > 125 equivalents of plasmid (Ep)/ml, and only 6 (7.8%) had viral loads of > 125 x 10(2) Ep/ml. A significant correlation (P < 0.029) was found between viral loads of > 125 x 10(2) Ep/ml and the neoplastic origin of end-stage renal disease. Analysis of 53 sequences cloned from a single individual demonstrated high sequence variability, as shown by the genetic distance of 40.2%. This genetic distance is comparable to that between the most divergent sequences of TLMV reported to date (43.5%). These data suggest that TLMV viral load is possibly related to the level of immunocompetence of hemodialysis patients; the genetic diversity of TLMV is extremely high; and co-infection by different strains is possible.

Prevalence and genomic variability of transfusion transmitted virus in Italian cryptogenic chronic liver disease and healthy blood donors

BACKGROUND

Infection with transfusion transmitted virus, a new member of the Parvoviridae family, has been found in patients both with chronic and fulminant post-transfusion cryptogenic hepatitis.

AIM

To evaluate the prevalence and clinical impact of transfusion transmitted virus infection in Italy.

PATIENTS AND METHODS

Studies were carried out on 256 patients and control subjects from three centres from Northern, Central and Southern Italy (92 nonA-nonC chronic hepatitis, 10 acute non fulminant cryptogenic hepatitis, 41 hepatitis C virus-related chronic hepatitis and 113 blood donors). Serum transfusion transmitted virus was detected by nested polymerase chain reaction using two overlapping sets of primers.

RESULTS

A total of 52 of the 92 patients (54.3%) with chronic cryptogenic liver disease and 17 of the 41 hepatitis C virus chronic hepatitis patients (41.4%) were transfusion transmitted virus-DNA positive. Transfusion transmitted virus co-infection in hepatitis C virus patients was not associated with either a higher severity of liver histology or higher alanine transaminase levels or signs of cholestasis, transfusion transmitted virus was found in 48 out of 113 (42.4%) blood donors. In the majority of samples, transfusion transmitted virus DNA was detected with only one of the two sets of primers used. Genotyping and phylogenetic analysis performed on 21 randomly selected viral isolates showed the presence of both type 1 and type 2 transfusion transmitted virus and allowed identification of two isolates with high homology to genotype 6, described, so far, mostly in Japan.

CONCLUSIONS

Transfusion transmitted virus type 1 and 2 infection is common among blood donors and patients with liver disease in Italy. The pathogenic potential of transfusion transmitted virus type 1 and 2 in nonA-nonC hepatitis patients is unlikely but further studies are needed to evaluate the epidemiological and clinical impact of other transfusion transmitted virus subtypes.

Clinicopathological study on TTV infection in hepatitis of unknown etiology

AIM: To investigate the state of infection, replication site, pathogenicity and clinical significance of transfusion transmitted virus (TTV) in patients with hepatitis, especially in patients of unknown etiology.

METHODS: Liver tissues taken from 136 cases of non-A non-G hepatitis were tested for TT virus antigen and nucleic acid by in situ hybridization (ISH) and nested-polymerase chain reaction (PCR). Among them, TT virus genome and its complemental strand were also detected in 24 cases of autopsy liver and extrahepatic tissues with ISH. Meanwhile, TTV DNA was detected in the sera of 187 hepatitis patients by nested-PCR. The pathological and clinical data of the cases infected with TTV only were analyzed.

RESULTS: In liver, the total positive rate of TTV DNA was 32.4% and the positive signals were located in the nuclei of hepatocytes. In serus, TTV DNA was detected in 21.4% cases of hepatitis A-G, 34.4% of non-A non-G hepatitis and 15% of healthy donors. The correspondence rate of TTV DNA detection between liver tissue with ISH and sera with PCR was 63.2% and 89.3% in the same liver tissues by ISH and by PCR, respectively. Using double-strand probes and single-strand probes designed to detect TTV genome, the correspondence rate of TTV DNA detected in liver and extrahepatic tissues was 85.7%. Using single-strand probes, TTV genome could be detected in liver and extrahepatic tissues by PCR, but its complemental strands (replication strands) could be observed only in livers. The liver function of most cases infected with TTV alone was abnormal and the liver tissues had different pathological damage such as ballooning, acidophilia degeneration, formation of apoptosis bodies and focus of necrosis, but the inflammation in the lobule and portal area was mild.

CONCLUSION: The positive rate of TTV DNA among cases of hepatitis was higher than that of donors, especially in patients with non-A non-G hepatitis, but most of them were coinfected with other hepatitis viruses. TTV can infect not only hepatocytes, but also extrahepatic tissues. However, the chief replication place may be liver. The infection of TTV may have some pathogenicity. Although the pathogenicity is comparatively weak, it can still damage the liver tissues. The lesions in acute hepatitis (AH) and chronic hepatitis (CH) are mild, but in severe hepatitis (SH), it can be very serious and cause liver function failure, therefore, we should pay more attention to TTV when studying the possible pathogens of so-called “Liver hepatitis of unknown etiology”.

Frequent detection of the replicative form of TT virus DNA in peripheral blood mononuclear cells and bone marrow cells in cancer patients

The TT virus (TTV), a member of a family of human viruses related to the circoviridae viruses, was associated initially with acute and chronic liver diseases. TTV consists of a single-stranded, circular DNA genome of 3.8 kilobases (kb) and at least three open reading frames (ORFs). The objective of the present study was to determine whether or not TTV replicated in peripheral blood mononuclear cells (PBMCs) and bone marrow cells (BMCs). DNA was extracted from the PBMCs or BMCs of 153 cancer patients and from the PBMCs of 50 healthy blood donors (the controls). By using a single round of polymerase chain reaction (PCR), TTV was detected in 98.6% (141 of 143) of the PBMCs and in 90% (9 of 10) of the BMCs from cancer patients. TTV DNA was detected in significantly fewer control subjects at 86% (43 of 50; P < 0.05). Strand-specific PCR (SSPCR) targeting the ORF2 of the common genotypes of TTV was developed specifically to detect TTV positive or negative strand DNA and to examine TTV replication. TTV positive strand DNA, which may be an intermediate of viral replication, was detected in 55.3% (78 of 141) of the TTV-infected PBMCs of the cancer patients and in 7% (3 of 43) of the controls (P < 0.001). The replicative form of TTV was also detectable in 55.6% (5 of 9) of the TTV-infected BMCs. The existence of double-strand (positive and negative strands) TTV DNA in PBMCs and BMCs of the cancer patients was also supported by the finding that TTV DNA extracted from these cells was resistant to S1 nuclease. Using in situ hybridization, TTV DNA was also demonstrated to be present in the nucleus of PBMCs. It is concluded that replicative intermediate forms of TTV DNA are present in both PBMCs and BMCs, indicating that blood cells may be a site of TTV replication.

Early acquisition of TT virus in infants: possible minor role of maternal transmission

This study assessed the prevalence of TT virus (TTV) viremia in pregnant women and evaluated the role of maternal transmission in early acquisition of TTV in infants in Taiwan. Two groups of pregnant women were screened for TTV using polymerase chain reaction. The first group included 135 healthy pregnant women attending the obstetrics department for routine prenatal care and the second group from 25 GB virus-C/hepatitis G virus (GBV-C/HGV)-infected mothers. In both groups, when TTV infection was found in mothers, serial serum samples were collected for the infants at regular intervals until 1 year of age and were tested for TTV DNA. The results showed that 40% (54/135) of the women undergoing routine prenatal care and 56% (14/25) of GBV-C/HGV-infected pregnant women were positive for TTV DNA (P = 0.137). Of the 54 TTV-infected mothers in the routine prenatal group, 29 and their 30 infants received regular follow-up. The positive rate of TTV DNA in infants was 40% (12/30) in the routine prenatal group and 29% (4/14) in the group with GBV-C/HGV-infected mothers (P = 0.463). All but 2 of the 16 TTV-infected infants had normal serum alanine aminotransferase levels during follow-up. The phylogenetic analysis in 7 mother-infant pairs showed that the homology was diverse in each pair and a close genetic relatedness was found in 2 mother-infant pairs. In conclusion, TTV viremia is common in pregnant Taiwanese women and their infants. However, the results suggest that maternal transmission may play only a minor role in early acquisition of TTV in infants.

Lack of transmission of TT virus through immunoglobulins

BACKGROUND

A high prevalence of TT virus (TTV) infection has been found in patients who received blood or blood components. Viral DNA was demonstrated in commercial preparations of FVIII and F IX, but very few data have been reported on immunoglobulins. The risk of TTV infection associated with intramuscular or IV immunoglobulin administration is unclear.

STUDY DESIGN AND METHODS

The prevalence of TTV infection in a group of patients undergoing lifelong therapy because of congenital immunodeficiency has been evaluated in a long term follow-up (median, 6 years). Seventeen patients with congenital immunodeficiency receiving monthly administration of IVIG were included in the study. TTV DNA was repeatedly evaluated by PCR in serum samples from each patient during the follow-up. Research of antibodies against TTV was not applicable, as the patients studied were unable to produce antibodies. The presence of TTV was also evaluated in 15 IVIG lots.

RESULTS

The total amount of immunoglobulin administered was 18,773 g. TTV infection was not found in any patients included in the study. None of the 15 immunoglobulin preparations analyzed was found positive for TTV DNA.

CONCLUSION

Despite the high prevalence of TTV in blood donors, commercial immunoglobulins are safe and unable to transmit TTV.

Prevalence of TT virus in healthy children and thalassemic pediatric and young adult patients

BACKGROUND

The recently discovered TT virus (TTV) has been shown to be highly prevalent in patients with cryptogenetic chronic liver disease and fulminant hepatitis. To study the frequency of TTV and to evaluate the possible association with liver disease, 37 pediatric and young adult patients with thalassemia, and 36 healthy children were included in the study. The sera of 100 blood donors selected randomly in the same period were also tested for TTV DNA.

METHODS

The TTV amplification by polymerase chain reaction (PCR) was performed using a first set of primers that recognize an internal sequence into N22 and a second set of primers amplifying a sequence within 5;NCR (5; noncoding region).

RESULTS

The first set of primers revealed TTV DNA in 73% of thalassemic patients, in 8% of healthy children, and in 5% of healthy blood donors. With the second set of primers, the prevalence of TTV DNA was, respectively, 100% in thalassemic patients, 44.5% in healthy pediatric patients, and 87% in healthy blood donors. All individuals who tested positive for TTV by the first set of primers were also positive by the second primer set. The TTV infection seemed not to be the cause of altered transaminase levels. Sequencing of TTV clones from thalassemic patients showed the presence of different TTV variants in the same serum.

CONCLUSION

The prevalence of TTV in polytransfused children is similar to that detected in blood donors. Moreover, TTV can be detected in healthy children of all ages. The presence of TTV seems to have no clinical significance.

Prevalence and genotypic distribution of TT virus in Athens, Greece

The prevalence of TT virus (TTV) infection in various population groups from Athens, Greece, was assessed by the polymerase chain reaction (PCR) using two primer sets from distinct regions of the genome: the conventional set derived from the open reading frame-1 (ORF-1) and the new, highly sensitive set targeting the region that includes the TATA signal localized upstream of ORF-2. Based on both primer sets, TTV DNA was detected in 42/50 (84.0%) healthy individuals, 42/50 (84.0%) chronic hepatitis C patients, 31/39 (79.5%) acute non-A-E hepatitis patients (group I), 14/16 (87.5%) renal failure patients with acute non-A-E hepatitis (group II), 47/50 (94.0%) intravenous drug users (IVDU), 36/50 (72.0%) hemophiliacs, and 21/31 (67.7%) hemodialysis patients. The presence of TTV was not associated with any particular risk group, and no differences were observed in relation to demographic, biochemical and virological characteristics between TTV DNA-positive and -negative patients. TTV did not seem to have a profound effect on the course of chronic C or acute non-A-E hepatitis either. Phylogenetic analysis revealed that TTV strains circulating in the greater metropolitan area of Athens belong not only to the G1 and G2 genotypes that are encountered worldwide, but also to G3 and to G5 that are found mainly in Europe and Asia, respectively. Further studies will shed light on the role of this highly prevalent virus.

Gross elevation of TT virus genome load in the peripheral blood mononuclear cells of cancer patients

TT virus (TTV) is a recently described circular DNA virus of about 3.8 kb, which is related to the circoviridae viruses. It is commonly detected in healthy subjects and no association with any specific disease has been established. TTV was initially thought to be hepatotropic, but subsequent reports have shown that it is detectable in other tissues, including kidney, prostate, mammary gland, brain, bone marrow, and peripheral blood mononuclear cells. Plasma samples from cancer patients and healthy subjects were tested for the presence or absence of TTV by heminested polymerase chain reaction (PCR). We also developed a quantitative competitive PCR (QC-PCR) assay for TTV that permits accurate measurement of TTV DNA load. Using this assay, the TTV genome load in peripheral blood mononuclear cells (PBMCs) of healthy control subjects (n = 50) and patients with various types of cancer (n = 148), including breast cancer, non-Hodgkin's lymphoma, colon cancer, hepatocellular carcinoma, nasopharyngeal carcinoma, and other cancers, was measured. TTV DNA was detected in 69 of 100 plasma samples (69%) of cancer patients tested and in 39 of 100 plasma samples (39%) randomly selected from 1000 plasma samples of blood donors (p < 0.05). TTV DNA was detectable in the PBMCs of 99% of the cancer patients and 86% of the controls. However, the median virus load was more than 100-fold higher in the cancer patients (3599 copies/100,000 cells) than among the controls (30 copies/100,000 cells; p < 0.0001). There was no significant difference in TTV load among the different cancer types. Using a cutoff value of >250 copies per 100,000 PBMCs, 93.2% of cancer patients were "positive" compared to only 4% of healthy control subjects. Almost all the cancer patients have TTV infection and their TTV genome load in PBMCs is significantly higher than that in control subjects. It remains to be elucidated whether such findings are specific to cancer patients or occur in all seriously ill subjects.

Comparison of systems performance for TT virus detection using PCR primer sets located in non-coding and coding regions of the viral genome

BACKGROUND

the heterogeneity of the TT virus (TTV) DNA prevalence values reported from comparable human cohorts suggests that diagnostic PCR protocols still require to be optimized.

OBJECTIVES

to design TTV PCR primer sets with low genotype restriction and to compare their performances with commonly used amplification systems.

STUDY DESIGN

we compared full length TTV genomic sequences and identified conserved nucleotide patterns in the 5' and 3' non-coding regions of the viral genome. This permitted to design two new primer sets usable for the PCR amplification of the most divergent human isolates of TTV described to date. The performances of these amplification systems were compared with those of three other PCR systems earlier used for prevalence studies.

RESULTS

the primer systems P5Bx and P3Bx exhibited higher PCR scores than the other systems tested; 14 to 34% improvement values were obtained, and divergent positive results of earlier described PCR systems were confirmed systematically by our new detection assays.

CONCLUSIONS

an optimized detection of TT virus DNA is a pre-requisite for the accurate epidemiological survey of viral infection and for the realization of phylogenetic studies. Such PCR systems with low genotype restriction will be helpful in the future for a better knowledge of natural history of TT virus infection.

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.

TT virus infection: prevalence of elevated viraemia and arguments for the immune control of viral load

BACKGROUND

The most recent polymerase chain reaction (PCR) detection protocols for the TT virus (TTV) permit one to identify the presence of viral DNA in the serum of a majority of healthy individuals, in the absence of any particular risk factor. This is in contrast with previous epidemiological studies that reported a higher prevalence of TTV infection in populations such as haemodialysis patients (HD), haemophiliacs, intravenous drug users or diabetics.

OBJECTIVES

To show that these discrepant results were due to the different sensitivity (number of viral copies detected) of the detection protocols used in initial and more recent epidemiological studies.

STUDY DESIGN AND RESULTS

We designed a standardised primary PCR assay that detects only viraemia >5x10(3) to 5x10(4) copies/ml for genotypes 1, 2 and 3, and compared the results of this test with those of a nested PCR assay which is 100-fold more sensitive. Viraemia >5x10(3) to 5x10(4) copies/ml were statistically more frequent in HD patients (54.3%), diabetics (54.7%), and HIV-infected patients with CD4 cells <200/mm(3) (69%) than in blood donors (37%) or HIV-infected patients with CD4 cells >500/mm(3) (33%).

CONCLUSIONS

These data suggest a possible relationship between the prevalence of elevated viral loads and the level of immunocompetence of the populations studied, and therefore that of an immune control of TTV viraemia. This corroborates previous findings showing that the stimulation of the immune system by an interferon treatment was able to clear TTV viraemia.

Inverse relationship between the titre of TT virus DNA and the CD4 cell count in patients infected with HIV

OBJECTIVES

To investigate the prevalence and relative titre of TT virus (TTV) DNA, and to examine the relationship between the extent of TTV viraemia and the immune status among 144 patients with HIV infection; 178 age- and sex-matched healthy individuals were also studied.

METHODS

TTV DNA was detected quantitatively by two distinct polymerase chain reaction (PCR) methods [untranslated region (UTR) and N22]. UTR PCR detects all TTV genotypes, and N22 PCR can primarily detect four major TTV genotypes (1-4).

RESULTS

Using UTR PCR and N22 PCR, respectively, TTV DNA was detected significantly more frequently in HIV-infected patients than in controls (99 versus 91%, P < 0.001; 56 versus 27%, P < 0.0001), and the relative titre (10N/ml) was significantly higher in HIV-infected patients [4.5 +/- 1.2 (mean +/- SD) versus 3.1 +/- 0.9, P < 0.0001; 2.6 +/- 1.5 versus 1.5 +/- 0.9, P < 0.0001]. Age, sex, co-infection with hepatitis B or C virus, and risk factors for HIV transmission did not appear to be significant factors associated with the titre of TTV viraemia. However, the titre of TTV DNA was significantly higher in HIV-infected patients with AIDS (P < 0.0001), those with low CD4 T cell count (P < 0.0001), or those with high HIV viral loads (P = 0.0047).

CONCLUSION

TTV is highly prevalent and high-titred in HIV-infected patients. The TTV viral load may reflect the degree of immune status of these immunocompromised hosts.

Genetic analysis of full-length genomes and subgenomic sequences of TT virus-like mini virus human isolates

The phylogenetic relationship between the complete genomic sequences of ten Japanese and one French isolate of TT virus-like mini virus (TLMV) was investigated. Analysis of the variability of the nucleotide sequences and the detection of signature patterns for overlapping genes suggested that ORFs 1 and 2 are probably functional. However, this was not the case for a putative third ORF, ORF3. Throughout the viral genome, several nucleotide or amino acid motifs that are conserved in circoviruses such as TT virus (TTV) and chicken anaemia virus were identified. Phylogenetic analysis distinguished three main groups of TLMV and allowed the identification of putative recombination breakpoints in the untranslated region. TLMV genomes were detected by PCR in the plasma of 38/50 French blood donors tested and were also identified in peripheral blood mononuclear cells, faeces and saliva. A phylogenetic study of 37 TLMV strains originating from France, Japan and Brazil showed that groupings were not related to geographical origin.