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

Gene expression of the human Torque Teno Virus isolate P/1C1

Torque Teno Virus (TTV) has been assigned to the floating genus Anellovirus. TTV ssDNA genomes have a size of 3.6 to 3.8 kb and display up to 30% nucleotide diversity. The pathogenic potential of TTV is under investigation. To address a putative link of pathogenicity with the observed sequence variations, the transcription profile of P/1C1 (genogroup 1) isolated from a patient diseased with a non A-G hepatitis was analysed. Four mRNAs were identified, which encoded the seven proteins ORF1, ORF1/1, ORF1/2, ORF2, ORF2/2, ORF3 and ORF4. Expression of the ORF1 protein and its splice variant ORF1/1 in cell culture was detected by an ORF1-specific antiserum. Analysis of N-terminal tagged P/1C1-encoded proteins revealed that ORF1, ORF1/1 and ORF1/2 were localised in the nucleoli, ORF3 and ORF4 resided in the nucleoplasm, ORF2/2 appeared either in the nucleoli or the whole nucleus while ORF2 was the only protein seen in the cytoplasm.

Unraveling the puzzle of human anellovirus infections by comparison with avian infections with the chicken anemia virus

Current clinical studies on human annelloviruses infections are directed towards finding an associated disease. In this review we have emphasized the many similarities between human anellovirus and avian circoviruses and the cell and tissue types infected by these pathogens. We have done this in order to explore whether knowledge acquired from natural and experimental avian infections could reflect and be extrapolated to the less well-characterized human annellovirus infections. The knowledge gained from the avian system may provide suggestions for decoding the enigmatic human anellovirus infections, and finding the specific disease or diseases caused by these human anellovirus infections. Each additional parallelism between chicken anemia virus (CAV) and Torque teno virus (TTV) further strengthens this premise. As we have seen information from human infections can also be used to better understand avian infections as well. Increased attention must be focused on the "hidden" or unrecognized, seemingly asymptomatic effects of circovirus and anellovirus infections. Understanding the facilitating effect of these infections on disease progression caused by other pathogens may help to explain differences in outcome of complicated poultry and human diseases. The final course of a pathogenic infection is determined by variations in the state of health of the host before, during and after contact with a pathogen, in addition to the phenotype of the pathogen and host. The health burden of circoviridae and anellovirus infections may be underestimated, due to lack of awareness of the need to search past the predominant clinical effect of identified pathogens and look for modulation of cellular-based immunity caused by co-infecting circoviruses, and by analogy, human anneloviruses.

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.

Functionality of the immune system in patients with chronic hepatitis C: trial by superinfections and vaccinations

Viral infections, specifically chronic, markedly influence the host response to subsequent infections and vaccinations. Does this apply to chronic hepatitis C (CHC)? The review considers this question with implications for the immune status and functionality of the immune system of a chronically HCV-infected host. The data collected here indicate that CHC may increase the risk of viral superinfections and modify their course by immunocompromising the host. Patients with CHC do not lose the 'memory' of previous infections and vaccinations but, apparently, have problems with building such immunity anew, as illustrated by their impaired response to hepatitis A and B vaccinations. This underlines the necessity of extra protection of CHC patients against blood-borne diseases, hepatitis A, possibly also varicella, influenza, tetanus, and diphtheria - immunity to which, in the Western population, appears to falter. Such immune protection has to be adapted to selective impairments of immune response characteristic to CHC. Some approaches to this are reviewed here and more need to be elaborated. Special attention has to be given to CHC patients who do not respond to common vaccines; further studies in this field are of great interest.

TT virus (TTV) genotyping in blood donors and multiple transfused patients in Brazil

TT virus (TTV) is widely distributed in the general population. The objective of the present study was to investigate the prevalence and distribution of TTV genotypes among blood donor candidates and multiple transfused patients in the Southeast region of the state of São Paulo, Brazil. TTV-DNA detection by amplification of a segment of the ORF-1 region, presented a prevalence of 11.9% in 270 serum samples from blood donors, of 46.2% in 18 samples from patients with coagulopathies, and of 31.8% in 15 samples from patients with hemoglobinopathies. When specific primers for the non-coding (UTR) region of the TTV genome were used the prevalences were 50.5%, 95.0%, and 82.0% for blood donors, patients with coagulopathies and patients with hemoglobinopathies, respectively. Positive samples from 49 individuals were sequenced and partial segments of 230 base pairs referring to the ORF-1 region of the TTV genome were used for the determination of their genotypes with the aid of phylogenetic analysis. The most frequent genotype was 1 (74.0%), followed by genotype 2 (26.0%). These data indicate a high prevalence of this virus in the populations of blood donors and transfused patients, providing further evidence for the role of transfusions as an efficient pathway in the transmission chain.

Comparison of tissue distribution, persistence, and molecular epidemiology of parvovirus B19 and novel human parvoviruses PARV4 and human bocavirus

Background. PARV4 and human bocavirus (HBoV) are newly discovered human parvoviruses with poorly understood epidemiologies and disease associations. We investigated the frequencies of persistence, tissue distribution, and influence of immunosuppression on replication of these viruses.

Methods. At autopsy, bone marrow, lymphoid tissue, and brain tissue from human immunodeficiency virus (HIV)—infected individuals with acquired immunodeficiency syndrome (AIDS) and those without AIDS and from HIV-uninfected individuals were screened for parvovirus B19, PARV4, and HBoV DNA by means of quantitative polymerase chain reaction analyses.

Results. B19 DNA was detected both in HIV-infected study subjects (13 of 24) and in HIV-uninfected study subjects (8 of 8), whereas PARV4 DNA was detected only in HIV-infected study subjects (17 of 24). HBoV DNA was not detected in any study subjects. The degree of immunosuppression with HIV infection did not influence B19 or PARV4 viral loads. B19 or PARV4 plasma viremia was not detected in any study subjects (n = 76; viral load <25 DNA copies/mL). A significantly older age distribution was found for study subjects infected with B19 genotype 2, compared with those infected with B19 genotype 1. Two genotypes of PARV4 were detected; study subjects carrying prototype PARV4 (genotype 1) were younger (all born after 1958) than those infected with genotype 2 (PARV5; study subjects born between 1949 and 1956).

Conclusions. Tight immune control of replication of B19 and PARV4 was retained despite profound immunosuppression. Recent genotype replacement of PARV4, combined with absent sequence diversity among genotype 1 sequences, suggests a recent, epidemic spread in the United Kingdom, potentially through transmission routes shared by HIV.

Torque teno virus (TTV): current status

Torque teno virus (TTV), currently classified into the family Circoviridae, genus Anellovirus, was first found in a patient with non-A-E hepatitis. TTV has a single stranded circular DNA of approximately 3.8 kb. TTVs are extraordinarily diverse, spanning five groups including SANBAN and SEN viruses. Torque teno mini virus (TTMV) with approximately 2.9 kb genome also has wide variants. Recently, two related 2.2- and 2.6-kb species joined this community. Recombinations between variants are frequent. This extensive TTV diversity remains unexplained; it is unclear how TTVs could be viable, and why they require such genetic variation. An unequivocal culture system is still not available. TTVs are ubiquitous in > 90% of adults worldwide but no human pathogenicity of TTV has been fully established. Epidemiological surveys need to specify the variants being studied and clinical targets, and must calibrate the sensitivity of the assay used. Potentially interesting observations include a higher viral load in patients with severe idiopathic inflammatory myopathies, cancer and lupus. Active replication was also found in infants with acute respiratory diseases. TTV/TTMV-related viruses were found in chimpanzees, apes, African monkeys and tupaias, and also in chickens, pigs, cows, sheep and dogs. Experimentally, rhesus monkeys were persistently infected by TTV, but only 1/53 chimpanzees. TTV transcribes three species of mRNAs, 3.0-, 1.2- and 1.0-kb in the ratio of 60:5:35. Recently, at least three mRNAs were shown in chicken anaemia virus. The genomic region -154/-76 contains a critical promoter. TTV seems to have at least three proteins; however, the definite functions of these proteins await further research work.

Transfusion transmitted virus: A review on its molecular characteristics and role in medicine

The present review gives an updated overview of transfusion transmitted virus (TTV), a novel agent, in relation to its molecular characteristics, epidemiological features, modes of transmission, tissue tropism, pathogenesis, role in various diseases and its eradication from the body. TTV, a DNA virus, is a single stranded, non-enveloped, 3.8 kb long DNA virus with a small and covalently closed circular genome comprising 3852 bases. It was tentatively designated Circinoviridae virus. TTV genome sequence is heterogeneous and reveals the existence of six different genotypes and several subtypes. TTV has been reported to transmit not only via parenteral routes, but also via alternate routes. This virus has been detected in different non-human primates as well. At present, TTV is detected by polymerase chain reaction (PCR) with no other available diagnostic assays. It shows its presence globally and was detected in high percent populations of healthy persons as well as in various disease groups. Initially it was supposed to have strong association with liver disease; however, there is little evidence to show its liver tropism and contribution in causing liver diseases. It shows high prevalence in hemodialysis patients, pointing towards its significance in renal diseases. In addition, TTV is associated with several infectious and non-infectious diseases. Though, its exact pathogenesis is not yet clear, TTV virus possibly resides and multiplies in bone marrow cells and peripheral blood mononuclear cells (PBMCs). Recently, attempts have been made to eradicate this virus with interferon treatment. More information is still needed to extricate various mysteries related to TTV.

Progression towards AIDS leads to increased torque teno virus and torque teno minivirus titers in tissues of HIV infected individuals

Torque teno virus (TTV) and Torque teno minivirus (TTMV) are highly prevalent in the general population and although no disease has been associated with these viruses yet, co-infections with other pathological viruses are frequent. Both viruses are extremely heterogeneous, especially for DNA viruses, and the role of the immune system in controlling the infections has yet to be established. In this study the TTV/TTMV viral loads in HIV positive tissues have been investigated for the first time. The titers of both TTV and TTMV were compared in the bone marrow and spleen tissues from three groups: HIV negative individuals, HIV positive individuals and HIV positive individuals who had progressed to AIDS, leading to immunosuppression. Limiting dilution PCR using primers situated in the UTR region of the genome were used to semi-quantitate the virus, and TTV and TTMV were differentiated using melting curve analysis of the PCR product. The AIDS group had significantly higher titers compared with both the HIV positive and negative groups for both bone marrow (AIDS vs. HIV positive P = 0.006, AIDS vs. HIV negative P < 0.001) and spleen (AIDS vs. HIV positive P = 0.022, AIDS vs. HIV negative P < 0.001). Analysis of TTV/TTMV titer with CD4 T lymphocyte count showed a significant inverse correlation however neither HCV co-infection or type of Anellovirus infection (single TTV or TTMV, or mixed TTV/TTMV) showed any significant correlation with virus titer. The results show a link between deterioration of the immune system and increased the viral loads in studied tissues.

Molecular epidemiology and clinical implications of TT virus (TTV) infection in Indian subjects

GOALS

This study was aimed at obtaining data on the epidemiology and clinical course of TT virus (TTV) infections among Indian subjects.

BACKGROUND

The TTV is a nonenveloped DNA virus, first identified in the peripheral blood of individuals with posttransfusion hepatitis of unknown etiology. There has been much conjecture regarding the disease association of this virus.

STUDY

A total of 494 serum specimens from various groups of high-risk and control subjects were screened for TTV DNA by a semi-nested PCR, using the ORF1-derived N22 primers. The sera were also screened for the HBsAg surface antigen by an ELISA, HCV RNA by a 5' NCR-based RT-PCR and GBV-C/HGV RNA by a 5' UTR-based RT-PCR. The clinical and hepatic profiles of the various subjects were also studied. Seventy-one randomly picked TTV isolates were directly sequenced and their phylogeny was studied.

RESULTS

TTV showed an overall positivity rate of 45.34% with a significant higher prevalence of 52.9% among the high-risk subjects as against a prevalence of 28% among healthy control subjects (P < 0.001). Abnormal liver function profiles were frequent among TTV viremic individuals and among the acute hepatitis cases studied a higher mortality rate correlated with a superimposed TTV infection. The 71 TTV isolates sequenced were found to belong to genotype 1a being closely homologous to TTV prototype TA278.

CONCLUSION

The TT virus shows a significant prevalence in the Indian population, particularly among subjects at risk for acquiring parenterally transmitted infections. Our study corroborates a putative role of the virus in the etiology of liver disease, particularly in coinfection with other agents.

Frequency of hepatitis G virus and transfusion-transmitted virus infection in type II diabetes mellitus

The hepatitis G virus (HGV) and transfusion-transmitted virus (TTV) are recently defined hepatitis viruses that the pathogenic roles in liver diseases are still not clear. It has been well known that some hepatitis virus, such as hepatitis C, might have an affinity to pancreatic islet cells. To investigate the relationship between the newly defined hepatitis viruses and diabetes mellitus (DM), we studied the prevalence of TTV and HGV in a type 2 diabetic patient population. Serum samples of 60 patients with DM and 45 healthy volunteers as control were taken. HGV RNA and TTV DNA was investigated by polymerase chain reaction. HGV was detected in none of diabetic patients (0%) and only one in control group (2.2%). However, TTV DNA was detected in 16 patients with DM (26%) and in five controls (11%). TTV was more prevalent in diabetic patients, but the difference between groups was not statistically significant (p > 0.05). These results revealed that TTV is more common in diabetic patients than in controls. At present, we don't know if this result is only a coincidence or a sign of potential association between TTV and DM. Further studies are certainly needed to elucidate a potential relationship.

Age-specific prevalence, transmission and phylogeny of TT virus in the Czech Republic

Background

TT virus is prevalent worldwide, but its prevalence and genotype distribution in Central and East-Europe has not been determined. The high prevalence of TTV in multiply-transfused patients points to the importance of a parenteral mode of transmission, but since more than half of the general population is infected other possible routes of transmission must be considered.

Methods

In our study, we investigated the epidemiology, transmission and phylogeny of TTV in the Czech Republic. The following groups were selected: a control group of 196 blood donors, 20 patients with hemophilia, 49 intravenous drug users, 100 sex workers, 50 penitentiary prisoners, 208 healthy children aged 1 to 14 years, 54 cord blood samples, 52 patients with non-A-E hepatitis, 74 patients with hepatitis C, and 51 blood donors with increased ALT levels. Primers specific for the non-coding region were used. The genotype distribution was studied in 70 TTV-positive samples.

Results

The prevalence rate of TTV among the Czech population was 52.6%. We have shown that TTV is not transmitted prenatally. Children were infected after birth with two peaks: one at the age of two years and the other after the beginning of primary school. Adults have shown a further increase in the TTV prevalence with age. The highest TTV prevalence was found in the group of patients who had received multiple blood transfusions. The TTV prevalence rate in subjects at an increased risk of sexual transmission was not significantly higher than in the general population. Genotypes G2 and G1 were most prevalent among the Czech population, followed by G8 and G3. The subjects positive for markers of HBV and/or HCV infection tested significantly more often TTV DNA positive, which is suggestive of a common route of transmission of these three infections.

Conclusions

This study on TTV prevalence, mode of transmission and age-specific prevalence is the most extensive study performed in Central and Eastern Europe. It showed insights into the epidemiology of TTV infection, but failed to associate TTV infection with clinical manifestations.

Genomic characterization of a Brazilian TT virus isolate closely related to SEN virus-F

SEN virus (SENV) is a circular, single stranded DNA virus that has been first characterized in the serum of a human immunodeficiency virus type 1 (HIV-1)-infected patient. Eight genotypes of SENV (A-H) have been identified and further recognized as variants of TT virus (TTV) in the family Circoviridae. Here we describe the first genomic characterization of a SENV isolate (5-A) from South America. Using 'universal' primers, able to amplify most, if not all, TTV/SENV genotypes, a segment of > 3 kb was amplified by polymerase chain reaction from the serum of an HIV-1 infected patient. The amplicon was cloned and a 3087-nucleotide sequence was determined, that showed a high (85%) homology with the sequence of the Italian isolate SENV-F. Proteins encoded by open reading frames (ORFs) 1 to 4 consisted of 758, 129, 276, and 267 amino acids, respectively. By phylogenetic analysis, isolate 5-A was classified into TTV genotype 19 (phylogenetic group 3), together with SENV-F and TTV isolate SAa-38.

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.

TT virus loads and lymphocyte subpopulations in children with acute respiratory diseases

TT virus (TTV) produces chronic plasma viremia in around 90% of healthy individuals of all ages and has, therefore, been proposed as a commensal human virus. We recently demonstrated that in children hospitalized for acute respiratory diseases high TTV loads were associated with severe forms of disease. Here, we report that in such children TTV loads showed an inverse correlation with the percentage of circulating total T and helper T cells and a direct correlation with the percentage of B cells. Thus, florid TTV replication might contribute to lymphocyte imbalances and, possibly, immunosuppressive effects, thus resembling related animal viruses.

TT virus infection in patients with chronic hepatitis B and response of TTV to lamivudine

AIM: To investigate the responses of TT virus (TTV) and hepatitis B virus (HBV) to a long-term lamivudine therapy.

METHODS: Sixteen patients infected with both TTV and HBV were treated with lamivudine 100 mg daily for 30 mo. Blood samples were drawn at the beginning of the therapy and subsequently at month 3, 6, 9, 12 and 30. Serum TTV was quantified by real time PCR and serum HBV was detected by hybridization assay and nested polymerase chain reaction.

RESULTS: TTV infection was detected in 100% of HBV-infected patients. Loss of serum TTV DNA after one year of treatment occurred in 1/16 (6%) patients. At the end of therapy, TTV DNA was positive in 94% of them. The decline of HBV viremia was evident at 3 mo after therapy and the response rate was 31%, 44%, 63%, 50% and 50% at month 3, 6, 9, 12 and 30, respectively.

CONCLUSION: TTV replication is not sensitive to lamivudine and is highly prevalent in HBV-infected patients.

Effect of immune modulation on TT virus (TTV) and TTV-like-mini-virus (TLMV) viremia

The present study was designed to investigate how two chronically replicating viruses, TT virus (TTV) and TTV-like mini virus (TLMV), interact with host defence systems. Successive serum samples from three groups of subjects, undergoing modifications of their antiviral defence, were tested by real-time PCR to measure changes in viral titers, and by sequence analyses to indicate whether increases in viremia could be attributed to infection with an unfamiliar strain: 1) in patients receiving immunosuppressants subsequent to kidney transplantation, viral titers tended to increase; 2) in soldiers undergoing extreme training known to cause immunosuppression, insignificant increases in titers were observed; and 3) interferon treatment of patients with hepatitis C virus caused a temporary decrease in TTV and TLMV titers. Increases in viremia were associated only occasionally with the appearance of novel strains. The above results add to knowledge on how these viruses are influenced by the host.

Serum concentrations of TT virus and TT virus-like mini virus in patients developing AIDS

Changes in viraemia of two chronically replicating circoviruses, TT virus (TTV) and TTV-like mini virus (TLMV), were investigated in patients developing HIV-related immune deficiency. In a few cases, episodes of a considerable increase in viraemia were observed, but in most patients there were no discernible increases as immune deficiency progressed. The deterioration of immune function associated with AIDS did not by itself have any obvious effect on TTV and TLMV.

High TT virus load as an independent factor associated with the occurrence of hepatocellular carcinoma among patients with hepatitis C virus-related chronic liver disease

The TT virus (TTV) load was estimated in sera obtained from 237 patients with hepatitis C virus (HCV)-related chronic liver disease including 42 patients with hepatocellular carcinoma (HCC), by real-time detection PCR using primers and a probe derived from the well-conserved untranslated region of the TTV genome, which can detect all known TTV genotypes. Of the 237 patients studied, 18 (8%) were negative for TTV DNA, 87 (37%) had low TTV viremia (1.3 x 10(2)-9.9 x 10(3) copies/ml), and 132 (56%) had high TTV viremia (1.0 x 10(4)-2.1 x 10(6) copies/ml). Various features were compared between the patients with high TTV load (n = 132) and those with no TTV viremia or low viral load (n = 105). High TTV viremia (> or =10(4) copies/ml) was significantly associated with higher age (P < 0.05), past history of blood transfusion (P < 0.001), complication of cirrhosis (P < 0.05) or HCC (P < 0.0005), lower HCV RNA titer (P < 0.05), and lower platelet count (P < 0.01). On multivariate logistic regression analysis, high TTV viral load was a significant risk factor for HCC (P < 0.05), independent from known risk factors such as complication of liver cirrhosis (P < 0.0001) and high age (> or =65 years, P < 0.05), among all 237 patients. Furthermore, high TTV viral load was an independent risk factor for HCC among the 90 cirrhotic patients (P < 0.05). These results suggest that a high TTV viral load is associated independently with the complication of HCC and may have prognostic significance in patients with HCV-related chronic liver disease, although whether high TTV viremia mediates the progression of HCV-related chronic liver disease remains to be defined.

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.

TTV viral load as a marker for immune reconstitution after initiation of HAART in HIV-infected patients

PURPOSE

To investigate whether TT virus (TTV) viral load may be used as a surrogate marker for functional immune reconstitution in HIV-infected patients receiving highly active antiretroviral therapy (HAART).

METHOD

Fifteen protease inhibitor-naïve HIV-infected patients were included in a longitudinal study. From each patient, three serum samples taken before HAART initiation and three samples taken during HAART were analyzed. TTV was detected by polymerase chain reaction (PCR) and was quantitated by competitive PCR. TTV viral heterogeneity was determined by restriction fragment length polymorphisms (RFLPs) and sequencing.

RESULTS

All 15 HIV-infected patients were TTV positive. No significant change in HIV RNA or TTV viral load was observed at the three time points before HAART initiation. Even though HAART lead to an immediate and significant reduction in HIV RNA (p =.0001), a significant reduction in TTV viral load (p =.0002) was not observed until after 3-5 months of HAART. Four patients did not have an increase in CD4+ T cell count after 1 year of HAART; however, a decrease in TTV viral load was still observed, and three of these patients had a reduction in HIV RNA. RFLPs and sequencing revealed that TTV is represented as a heterogeneous population of virus in HIV-infected patients.

CONCLUSION

This pilot study suggests that HAART leads to improved immunological responses, even in patients who do not have an increase in CD4+ T cell counts. We propose that the change in TTV viral load may be useful in the evaluation of cellular immune response at a functional level in HIV-infected patients who receive HAART.