Torque Teno Virus Load Is Associated With Centers for Disease Control and Prevention Stage and CD4+ Cell Count in People Living With Human Immunodeficiency Virus but Seems Unrelated to AIDS-Defining Events and Human Pegivirus Load.

BACKGROUND: Torque teno virus (TTV) is part of the human virome. TTV load was related to the immune status in patients after organ transplantation. We hypothesize that TTV load could be an additional marker for immune function in people living with HIV (PLWH). METHODS: In this analysis, serum samples of PLWH from the RESINA multicenter cohort were reanalyzed for TTV. Investigated clinical and epidemiological parameters included human pegivirus load, patient age and sex, HIV load, CD4+ T-cell count (Centers for Disease Control and Prevention [CDC] stage 1, 2, or 3), and CDC clinical stage (1993 CDC classification system; stage A, B, or C) before initiation of antiretroviral therapy. Regression analysis was used to detect possible associations among parameters. RESULTS: Our analysis confirmed TTV as a strong predictor of CD4+ T-cell count and CDC class 3. This relationship was used to propose a first classification of TTV load with regard to clinical stage. We found no association with clinical CDC stages A-C. The human pegivirus load was inversely correlated with HIV load but not TTV load. CONCLUSIONS: TTV load was associated with immunodeficiency in PLWH. Neither TTV nor HIV load were predictive for the clinical categories of HIV infection.

Longitudinal monitoring of Torque Teno virus DNAemia in kidney transplant recipients correlates with long-term complications of inadequate immunosuppression.

Optimization of individual immunosuppression, which reduces the risks of both graft loss and patients' death, is considered the best approach to improve long-term outcomes of renal transplantation. Torque Teno Virus (TTV) DNAemia has emerged as a potential biomarker reflecting the depth of therapeutic immunosuppression during the initial year post-transplantation. However, its efficacy in long-term monitoring remains uncertain. In a cohort study involving 34 stable kidney transplant recipients and 124 healthy volunteers, we established lower and upper TTV DNAemia thresholds (3.75-5.1 log10 cp/mL) correlating with T-cell activatability, antibody response against flu vaccine, and risk for subsequent serious infections or cancer over 50 months. Validation in an independent cohort of 92 recipients confirmed that maintaining TTV DNAemia within this range in >50% of follow-up time points was associated with reduced risks of complications due to inadequate immunosuppression, including de novo DSA, biopsy-proven antibody-mediated rejection, graft loss, infections, or cancer. Multivariate analysis highlighted "in-target" TTV DNAemia as the sole independent variable significantly linked to decreased risk for long-term complications due to inadequate immunosuppression (odds ratio [OR]: 0.27 [0.09-0.77]; p = 0.019). Our data suggest that the longitudinal monitoring of TTV DNAemia in kidney transplant recipients could help preventing the long-term complications due to inadequate immunosuppression.

TTV and CMV viral load dynamics: Which emerges first during immunosuppression?

Novel biomarkers reflecting the degree of immunosuppression in transplant patients are required to ensure eventual personalized equilibrium between rejection and infection risks. With the above aim, Torque Teno Virus (TTV) viremia was precisely examined in a large cohort of transplanted immunocompromised patients (192 hematological and 60 solid organ transplant recipients) being monitored for Cytomegalovirus reactivation. TTV load was measured in 2612 plasma samples from 448 patients. The results revealed a significant increase in TTV viral load approximately 14 days following CMV reactivation/infection in solid organ transplant (SOT) patients. No recognizable difference in TTV load was noted among hematological patients during the entire timeframe analyzed. Furthermore, a temporal gap of approximately 30 days was noted between the viral load peaks reached by the two viruses, with Cytomegalovirus (CMV) preceding TTV. It was not possible to establish a correlation between CMV reactivation/infection and TTV viremia in hematological patients. On the other hand, the SOT patient cohort allowed us to analyze viral kinetics and draw intriguing conclusions. Taken together, the data suggest, to our knowledge for the first time, that CMV infection itself could potentially cause an increase in TTV load in the peripheral blood of patients undergoing immunosuppressive therapy.

High Torque teno virus load and outcome of patients undergoing allogeneic hematopoietic cell transplantation.

Quantification of Torque teno virus (TTV) load emerged as a marker of immunosuppression. Associations of TTV load with complications and survival after allogeneic hematopoietic cell transplantation (allo-HCT) were controversial in published studies. In this prospective study, we aimed to identify factors influencing TTV load after allo-HCT and to determine whether the TTV load is associated with complications or outcomes. Seventy allo-HCT recipients were included. TTV DNA load was quantified in 469 plasma samples of 70 patients from Day (D) 15 before D120 after transplantation. The influence of transplant characteristics on TTV load and the associations of TTV load with viral infections, acute graft versus host disease, mortality, and relapse were analyzed. More than 80% of patients were TTV DNA positive from D30 after transplantation onwards. Median TTV load increased between D30 and D60 post-transplantation. Patients with lymphoid malignancies had higher TTV load than those with myeloid malignancies. Myeloablative conditioning was associated with higher TTV loads. Patients with no measurable residual disease at transplant had higher TTV loads. High TTV load at D90 post-transplantation was associated with lower overall survival and at D120 post-transplantation was associated with higher relapse rate. In conclusion, TTV load at time points later than D90 after allo-HCT may be useful to assess prognosis.

Torque teno virus load as marker of rejection and infection in solid organ transplantation - A systematic review and meta-analysis.

Balancing immunosuppression to prevent rejection in solid organ transplant (SOT) recipients remains challenging. Torque teno virus (TTV), a commensal non-pathogenic virus, has been proposed as marker of functional immunity: higher loads correspond to over-immunosuppression, and lower loads to under-immunosuppression. This review offers an overview of the current evidence of the association between TTV-load and infection and rejection after SOT. A systematic literature search strategy, deposited in the PROSPERO registry, resulted in 548 records. After screening, 23 original and peer-reviewed articles were assessed investigating the association between TTV-load, infection and/or rejection in SOT. The Quality in Prognostic Studies (QUIPS)-tool was used to assess the risk of bias. Meta-analysis with random-effects was performed on results with similar outcomes and exposure measures. Most of the included studies involved retrospective cohorts in which the TTV-load was measured longitudinally, within the first 2 years post-transplantation. Infection outcomes differed between studies and included viral, bacterial, parasitic and fungal infections. Rejection was defined by biopsy confirmation or initiation of rejection treatment. Twelve out of 16 studies reported an association between high TTV-load and infections, whereas 13 out of 15 reported an association between low TTV-load and rejection. Meta-analysis showed an increased risk of infection (OR: 1.16, 95% CI: 1.03-1.32; HR: 1.05, 95% CI: 0.97-1.14) and a decreased risk of rejection (OR: 0.90, 95% CI: 0.87-0.94; HR: 0.74, 95% CI: 0.71-0.76) per 1 log TTV-load increase. The qualitative assessment showed varying risks of bias in the included studies. This systematic review and meta-analysis indicates that blood TTV-load measured within the first 2 years after SOT is associated with the risk of infection or allograft rejection, although substantial risk of bias in the studies included warrant cautious interpretation. The results in this review provide a rationale for larger, prospective, studies into TTV as marker of infection and rejection after SOT.

The assessment of microbial infection in children with autism spectrum disorders and genetic folate cycle deficiency.

BACKGROUND: The results of disparate clinical studies indicate abnormally frequent cases of certain microorganisms in children with autism spectrum disorders (ASD). However, these data require clarification and systematization. The study aims to study the structure of the microbial profile in children with ASD and genetic folate cycle deficiency (GFCD) and consider differences in diagnostic approaches for identifying microorganisms of different types. METHODS: The study analyzed medical data from 240 children (187 boys and 63 girls) with GFCD aged 2 to 9 years. The children had clinical manifestations of ASD (the study group, SG). The control group (CG) included 53 clinically healthy children (37 boys and 16 girls) of the same age but without GFCD. Both groups of children were tested on active herpetic infections (HSV-1/2, VZV, EBV, CMV, HHV-6, HHV-7, HHV-8), ТТV, Streptococcus pyogenes, Candida albicans, Borrelia burgdorferi, Mycoplasma pneumoniae, Chlamydia pneumoniae, Yersinia enterocolitica, Toxoplasma gondii, congenital CMV neuroinfection and postnatal HSV-1/2 encephalitis. The testing used diagnostic methods specified in PubMed-indexed studies. RESULTS: In the SG, TTV was found in 196 children (82%), HHV-7 - in 172 (72%), HHV-6 - in 162 (68%), EBV - in 153 (64%), Streptococcus pyogenes - in 127 (53%), Candida albicans - in 116 (48%), Borrelia - in 107 (45%), Mycoplasma pneumoniae - in 94 (39%), Chlamydia pneumoniae - in 85 (35%), Yersinia entеrocolitica - in 71 (30%), Toxoplasma gondii - in 54 (23%), congenital CMV neuroinfection - in 26 (11%), and postnatal HSV-1/2 encephalitis - in 11 children (5% of cases) (p < p0.05; Z < Z0.05). In the SG, there was a higher microbial load in older children (p < p0.05; Z < Z0.05). No gender differences were found. CONCLUSIONS: The study described and characterized a specific abnormal microbial spectrum with a predominance of viral opportunistic agents in children with ASD associated with GFCD.

Torque teno virus (TTV): A gentle spy virus of immune status, predictive marker of seroconversion to COVID-19 vaccine in kidney and lung transplant recipients.

To date, no comprehensive marker to monitor the immune status of patients is available. Given that Torque teno virus (TTV), a known human virome component, has previously been identified as a marker of immunocompetence, it was retrospectively investigated whether TTV viral load may also represent a marker of ability to develop antibody in response to COVID-19-BNT162B2 vaccine in solid organ transplant recipients (SOT). Specifically, 273 samples from 146 kidney and 26 lung transplant recipients after successive doses of vaccine were analyzed. An inverse correlation was observed within the TTV copy number and anti-Spike IgG antibody titer with a progressive decrease in viremia the further away from the transplant date. Analyzing the data obtained after the second dose, a significant difference in TTV copy number between responsive and nonresponsive patients was observed, considering a 5 log10 TTV copies/mL threshold to discriminate between the two groups. Moreover, for 86 patients followed in their response to the second and third vaccination doses a 6 log10 TTV copies/mL threshold was used to predict responsivity to the booster dose. Although further investigation is necessary, possibly extending the analysis to other patient categories, this study suggests that TTV can be used as a good marker of vaccine response in transplant patients.

Assessment of the potential value of plasma Torque Teno virus DNA load monitoring to predict cytomegalovirus DNAemia in patients with hematological malignancies treated with small molecule inhibitors: A proof-of-concept study.

It is unknown whether Torque Teno virus (TTV) DNA load monitoring could anticipate the development of infectious events in hematological patients undergoing treatment with small molecular targeting agents. We characterized the kinetics of plasma TTV DNA in patients treated with ibrutinib or ruxolitinib and assessed whether TTV DNA load monitoring could predict the occurrence of Cytomegalovirus (CMV) DNAemia or the magnitude of CMV-specific T-cell responses. Multicenter, retrospective, observational study, recruiting 20 patients treated with ibrutinib and 21 with ruxolitinib. Plasma TTV and CMV DNA loads were quantified by real-time PCR at baseline and days +15, +30, +45, +60, +75, +90, +120, +150, and +180 after treatment inception. Enumeration of CMV-specific interferon-γ (IFN-γ)-producing CD8+ and CD4+ T-cells in whole blood was performed by flow cytometry. Median TTV DNA load in ibrutinib-treated patients increased significantly (p = 0.025) from baseline (median: 5.76 log10 copies/mL) to day +120 (median: 7.83 log10 copies/mL). A moderate inverse correlation (Rho = -0.46; p < 0.001) was found between TTV DNA load and absolute lymphocyte count. In ruxolitinib-treated patients, TTV DNA load quantified at baseline was not significantly different from that measured after treatment inception (p ≥ 0.12). TTV DNA load was not predictive of the subsequent occurrence of CMV DNAemia in either patient group. No correlation was observed between TTV DNA loads and CMV-specific IFN-γ-producing CD8+ and CD4+ T-cell counts in either patient group. The data did not support the hypothesis that TTV DNA load monitoring in hematological patients treated with ibrutinib or ruxolitinib could be useful to predict either the occurrence of CMV DNAemia or the level of CMV-specific T-cell reconstitution; nevertheless, due to the small sample size, further studies involving larger cohorts are warranted to elucidate this issue.

Monitoring of plasma Torque teno virus, total Anelloviridae and Human Pegivirus 1 viral load for the prediction of infectious events and acute graft versus host disease in the allogeneic hematopoietic stem cell transplantation setting.

Anelloviridae and Human Pegivirus 1 (HPgV-1) blood burden have been postulated to behave as surrogate markers for immunosuppression in transplant recipients. Here, we assessed the potential utility plasma Torque teno virus (TTV), total Anelloviridae (TAV), and HPgV-1 load monitoring for the identification of allogeneic hematopoietic stem cell transplantation recipients (allo-HSCT) at increased risk of infectious events or acute graft versus host disease (aGvHD). In this single-center, observational study, plasma TTV DNA, TAV DNA, and HPgV-1 RNA loads were monitored in 75 nonconsecutive allo-HSCT recipients (median age, 54 years). Monitoring was conducted before at baseline or by days +30, +60, +90, +120, and +180 after transplantation. Pneumonia due to different viruses or Pneumocystis jirovecii, BK polyomavirus-associated haemorrhagic cystitis (BKPyV-HC), and Cytomegalovirus DNAemia were the infectious events considered in the current study. Kinetics of plasma TTV, TAV DNA, and HPgV-1 RNA load was comparable, with though and peak levels measured by days +30 and day +90 (+120 for HPgV-1). Forty patients (53%) developed one or more infectious events during the first 180 days after allo-HSCT, whereas 29 patients (39%) had aGvHD (grade II-IV in 18). Neither, TTV, TAV, nor HPgV-1 loads were predictive of overall infection or CMV DNAemia. A TTV DNA load cut-off ≥4.40 log10 (pretransplant) and ≥4.58 log10 (baseline) copies/mL predicted the occurrence of BKPyV-HC (sensitivity ≥89%, negative predictive value, ≥96%). TTV DNA loads ≥3.38 log10 by day +30 anticipated the occurrence of aGvHD (sensitivity, 90%; negative predictive value, 97%). Pretransplant HPgV-1 loads were significantly lower (p = 0.03) in patients who had aGvHD than in those who did not. Monitoring of TTV DNA or HPgV-1 RNA plasma levels either before or early after transplantation may be ancillary to identify allo-HSCT recipients at increased risk of BKPyV-HC or aGvHD.

Better detection of Torque teno virus in children with leukemia by metagenomic sequencing than by quantitative PCR.

Torque teno virus (TTV) is a group of chronically persisting viruses with a short circular DNA genome. TTV demonstrates a wide sequence diversity and a large majority of humans are chronically infected by one or more types of TTV. As TTV is ubiquitous, and viral replication correlates with immune status, TTV has been studied as a marker to assess global functional immune competence in transplant recipients. Most studies of the prevalence, amounts, and variation in TTV have been performed using PCR assays. We here present a comparison of the most frequently used quantitative PCR (qPCR) assay for TTV with shotgun metagenomic sequencing for detection and characterization of TTV in a cohort of pediatric cancer patients. The results show that TTV is more common than the qPCR assays indicate, and analysis of the TTV genome sequences indicate that a qPCR with primers and probe designed on a conserved region of the TTV genome may fail to detect some of the TTV strains found in this study.

Viruses, friends, and foes: The case of Torque Teno Virus and the net state of immunosuppression.

New reliable biomarkers are needed to improve individual risk assessment for post-transplant infection, acute graft rejection and other immune-related complications after solid organ transplantation (SOT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). One promising strategy relies on the monitoring of replication kinetics of virome components as functional surrogate for the net state of immunosuppression. Torque Teno Virus (TTV) is a small, non-enveloped, circular, single-stranded DNA anellovirus with no attributable pathological effects. A major component of the human blood virome, TTV exhibits various features that facilitate its application as immune biomarker: high prevalence rates, nearly ubiquitous distribution, stable viral loads with little intra-individual variability, insensitivity to antiviral drugs, and availability of commercial PCR assays for DNA quantification. The present review summarizes the available studies supporting the use of post-transplant TTV viremia to predict patient and graft outcomes after SOT and allo-HSCT. Taken together, this evidence suggests that high or increasing TTV DNA levels precede the occurrence of infectious complications in the SOT setting, whereas low or decreasing viral loads are associated with the development of acute rejection. The interpretation in allo-HSCT recipients is further complicated by complex interplay with the underlying disease, conditioning regimen, and timing of recovery of lymphocyte counts, although TTV kinetics may act as a marker of immunological reconstitution at the early post-transplant period. The standardization of PCR methods and reporting units for TTV DNAemia and the results from ongoing interventional trials evaluating a TTV load-guided strategy to adjust immunosuppressive therapy are achievements expected in the coming years.

Association of post-transplantation anellovirus viral load with kidney transplant rejection in children.

BACKGROUND: Post-transplantation immunosuppressive therapy reduces the risk of graft rejection but raises the risk of infection and malignancy. A biomarker of the level of immunosuppression can be helpful in monitoring immunosuppressive therapy. Inverse correlation between Torque teno virus (TTV) from the Anelloviridae (AV) family load and immune competence was described in previous studies. The aim of this study was to analyze the association between AV family viruses' kinetics and the risk for graft rejection in the first year after kidney transplantation in children. METHODS: The titers of three genera (TTV, TTMDV, and TTMV) from the AV family were monitored by real-time PCR in consecutive samples from children before and after kidney transplantation. RESULTS: Twenty-one children who underwent kidney transplantation were enrolled. Five out of 21 patients experienced acute graft rejection within a year from transplantation. We found that in patients who experienced graft rejection, the median titers of TTV and total AV titers at 5-6 months post-transplantation were lower than in those who did not. Using a threshold determined by ROC analysis, significant differences in TTV and total AV load were found between patients who had or did not have graft rejection (p = 0.002 and 0.004, respectively). No association was found between the dominance of any AV genus titer and the likelihood of rejection. CONCLUSION: This pilot study suggests that children after kidney transplantation with low TTV and total AV titers 5-6 months post-transplantation are at increased risk for graft rejection within a year after transplantation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Kinetics of Torque Teno virus DNA in stools may predict occurrence of acute intestinal graft versus host disease early after allogeneic hematopoietic stem cell transplantation.

Torque Teno virus (TTV) DNA load in blood may act as a marker of immune competence after allogeneic hematopoietic stem cell transplant recipients (allo-HSCT). Conflicting data have been reported as to the value of this biomarker for anticipating acute Graft versus host disease (aGvHD) occurrence. Here, we hypothesized that quantitation of TTV DNA load in stool specimens early after allo-HSCT could be used to identify patients at high risk of acute intestinal graft versus host disease (aIGvHD). In this prospective two-center study, we recruited a total of 83 nonconsecutive adult patients undergoing allo-HSCT. The study period comprised the first 120 days after allo-HSCT. TTV DNA was quantitated in paired stool samples collected at a median of 2 days prior to cell infusion and at a median of 14 days after allo-HSCT by real-time PCR. Thirty-seven patients developed aGVHD, of whom 25 had aIGVHD (diagnosed at a median of 42 days after allo-HSCT). Median TTV DNA load values in posttransplant stools specimens were comparable (P = .34) in patients with or without subsequent aIGvHD; nevertheless, a falling trajectory (decrease in TTV DNA load >0.5 log10 copies/0.1 g) in paired pretransplant and posttransplant specimens was independently associated with the occurrence of aIGvHD (OR, 5.2; 95% CI, 1.3-21.3; P = .02). Notably, displaying a rising trajectory had a negative predictive value of 87.5% for aIGvHD. In summary, in this hypothesis-generating study, we suggest that the decrease in TTV DNA load from baseline in stool specimens may identify patients at risk of aIGVHD.

Torque teno viral load reflects immunosuppression in paediatric kidney-transplanted patients-a pilot study.

BACKGROUND: Chronic deterioration of kidney graft function is related to inadequate immunosuppression (IS). A novel tool to assess the individual net state of IS in transplanted patients might be the monitoring of Torque teno virus (TTV) viral load. TTV is a non-pathogen virus detectable in almost all individuals. TTV level in the peripheral blood has been linked to the immune-competence of its host and should thus reflect IS after solid organ transplantation. METHODS: TTV plasma load was quantified monthly by RT-PCR for a period of 1 year in 45 kidney-transplanted children. Post-transplant time was at least 3 months. The relation of the virus DNA levels to IS and transplant-specific clinical and laboratory parameters was analysed longitudinally. RESULTS: TTV DNA was detectable in 94.5% of the plasma samples. There was a significant association with the post-transplant follow-up time as well as with the type of IS regimen, with lower virus loads in patients after longer post-transplant time and mTOR inhibitor-based IS. Furthermore, a significant positive correlation with the dose of prednisolone and mycophenolate mofetil was found. CONCLUSIONS: TTV levels show an association/correlation with the strength of IS. Further studies are needed in order to evaluate TTV measurement as a tool for IS monitoring for hard clinical outcomes such as presence of donor-specific antibodies, rejections or infections-common consequences of insufficient or too intense IS.

The Value of Torque Teno Virus (TTV) as a Marker for the Degree of Immunosuppression in Adult Patients after Hematopoietic Stem Cell Transplantation (HSCT).

Torque teno virus (TTV) is a nonenveloped, single-stranded, circular DNA virus of the family of Anelloviridae. The first contact with TTV usually occurs in early childhood, followed by persistent infection in bone marrow and lymphocytes. Increased levels of TTV-DNA are found in the serum in various states of immune deficiency. The objective of this study was to assess if monitoring of TTV viremia after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a predictive marker for immune-related clinical complications. In a retrospective study, 2054 whole-blood samples from 123 patients were tested for viral loads of TTV-DNA by real-time PCR within 345 days after allo-HSCT. We enrolled all patients who underwent allo-HSCT between September 2015 and April 2018. Clinical and laboratory data were collected and statistically analyzed. Patients with an underlying lymphatic malignancy had significantly higher torque teno (TT) viral loads compared with patients with an underlying malignant myeloid disease (P < .05). Complete remission before allo-HSCT correlated significantly with higher TT viral loads after allo-HSCT (P < .05). Myeloablative conditioning regimens led to significantly higher TT viral loads than reduced-intensity conditioning regimens (P < .05). A higher anti-thymocyte globulin (ATG) dose was associated with a significantly higher TT viral load. We did not observe any significant differences of TT viral load correlating with accompanying clinically relevant events such as virus reactivations (cytomegalovirus, Epstein-Barr virus, Adenovirus), acute graft-versus-host disease (aGVHD), relapse, or death. TT viral load after allo-HSCT did weakly correlate with T cell, T suppressor cell, T helper cell, and natural killer and B cell count. Although statistically significant differences between study groups were observed, virus reactivations, aGVHD, and clinical outcomes could not be predicted by monitoring TTV viremia. Therefore, TTV seems not to be suitable as a marker for the degree of immunosuppression or as a prognostic marker for clinically critical events in patients after allo-HSCT.

Kinetics of Alphatorquevirus plasma DNAemia at late times after allogeneic hematopoietic stem cell transplantation.

Torque teno virus (TTV) plasma DNA load has been consistently shown to be a surrogate biomarker of immunosuppression in solid organ transplant recipients. It is uncertain whether it may behave similarly in allogeneic hematopoietic stem cell transplant recipients (allo-HSCT). Here, we characterized the dynamics of TTV DNAemia in patients undergoing T-cell replete allo-SCT at late times after transplantation (> day + 100). This retrospective single-center observational study included 33 allo-HSCT patients. Plasma TTV DNA loads were quantified by real-time PCR before initiating the conditioning regimen and at different time points after transplant. Absolute lymphocyte counts (ALC) were measured by flow cytometry. Overall, TTV DNA load increased steadily after engraftment, reaching a peak by day + 90; afterwards, it remained relatively constant until day + 210. TTV DNA loads measured within days + 120 and + 210 correlated inversely with paired ALC, while both parameters did correlate directly within days + 20 and + 60. The median TTV DNA area under a curve between days + 90 and + 210 [(AUC)90-210] was significantly higher in patients who received corticosteroids within this time frame for treatment of graft versus host disease (either acute, chronic or both) than in controls (P = 0.025). In summary, TTV DNA load may mirror the degree of immunosuppression at late times after allo-HSCT.

Torquetenovirus Dynamics and Immune Marker Properties in Patients Following Allogeneic Hematopoietic Stem Cell Transplantation: A Prospective Longitudinal Study.

Torquetenovirus (TTV) has been proposed as a marker of immune function in patients receiving immunosuppression after solid organ transplantation. This study aimed to define TTV plasma dynamics and investigate clinical associations in patients following allogeneic hematopoietic stem cell transplantation (HSCT). This was a single-center prospective longitudinal study involving 50 consecutive patients treated with HSCT between March 2015 and April 2016. TTV plasma DNA levels were measured with quantitative PCR at 12 consecutive time points during the first year after HSCT. Forty of the 50 patients (80%) had detectable TTV viremia before HSCT (median level, 5.37 log10 copies/mL; interquartile range [IQR], 3.51-6.44 log10 copies/mL). All patients subsequently developed TTV viremia during the follow-up period. Plasma viral loads evolved dynamically over time, with a peak of 8.32 log10 copies/mL (IQR, 7.33-9.35 log10 copies/mL) occurring at 79 days (IQR, 50-117 days) following HSCT and a stable plateau toward the end of the follow-up period. The type of malignancy, the use of antithymocyte globulin during conditioning, and the occurrence of acute graft-versus-host disease requiring systemic therapy had temporary effects on TTV dynamics. TTV levels showed a significant correlation with absolute lymphocyte counts following engraftment (rs = -.27; P < .01) and with cytomegalovirus (CMV; rs=.39; P < .01) and Epstein-Barr virus (EBV; rs=.45; P = .02) viral loads during phases of viremia. Immune-related clinical events were not predicted by TTV levels. TTV viremia occurred universally and was sustained throughout the first year after HSCT. Several variables and events before and after HSCT were correlated with TTV levels and hint toward immune marker properties of TTV, but their complex interactions might perturb the capability of TTV to predict immune-related complications in this population.

Kinetics of torque teno virus DNA load in saliva and plasma following allogeneic hematopoietic stem cell transplantation.

Plasma torque teno virus (TTV) DNA load directly correlates with the degree of T-cell immune reconstitution early after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, the kinetics of oral TTV DNA shedding was examined to assess whether quantitation of TTV DNA load in saliva may either replace or complement that in plasma for predicting lymphocyte (ALC) reconstitution after engraftment. This prospective observational study enrolled 38 nonconsecutive allo-HSCT recipients. Saliva and plasma specimens were collected at baseline (pretransplant) and at around days +30, +50, and +90 after allo-HSCT. TTV DNA was quantitated in both specimen types by real-time PCR. ALCs were measured by cytometry. A total of 104 paired saliva and plasma specimens were available for TTV PCR analyses. TTV DNA was detected more frequently in saliva than in plasma specimens at all time points (overall, 94.2% vs 86.5%). Increasing levels of TTV DNA were seen in both specimen types from day +30 to day +90 after transplantation. Overall, TTV DNA loads were significantly higher in saliva than in plasma specimens (P = .0002) and correlated significantly (P ≤ .0001). A direct correlation between TTV DNA loads in saliva and plasma and ALCs was observed after engraftment (P = .034 and P = .002, respectively). Future studies should be aimed at determining whether monitoring of oral TTV DNA shedding may be of any utility for inference of immune reconstitution after allo-HSCT.

Torque teno virus dynamics during the first year of life.

BACKGROUND: Torque teno virus is a small chronically persisting circular negative ssDNA virus reaching near 100% prevalence. It is reported to be a marker for immune function in immunocompromised patients. The possibility of vertical maternal-fetal transmission remains controversial but incidence rate of TTV DNA in children increased with age. TTV dynamics well studied for allogeneic hematopoietic stem cell transplantation as a predictor of post-transplant complications but there is no viral proliferation kinetics data for other patient groups or healthy individuals. The aim of this study was to determine TTV dynamics during the first year of life of healthy infants. METHODS: Ninety eight clinically healthy breastfeeding infants (1-12 months of age) were analyzed by quantitative PCR for the whole blood TTV load with the test sensitivity of about 1000 viral copies per milliliter of blood (total number of samples including repeatedly tested infants was 109). RESULTS: 67% of all analyzed samples were TTV-positive demonstrating significant positive correlation between age and TTV load (r = 0.81, p < 0.01). CONCLUSIONS: This is the first study to suggest that viral load increases during the first year of life reaching a plateau after 6 months with strong proliferation for the first 60 days. Our data well correlates with TTV dynamics in patients following allogeneic hematopoietic stem cell transplantation.

Prevalence of human anelloviruses in Romanian healthy subjects and patients with common pathologies.

BACKGROUND: Human anelloviruses (TTV, TTMDV and TTMV) are at high prevalence all across the globe, having also a controversial disease-inducing potential. This study aimed to estimate the prevalence of anelloviral DNA in the Romanian human population and to investigate the association of infections with common pathologies in Romanian population. METHODS: After informed consent, blood samples were collected from 2000 subjects represented by: clinically healthy individuals (n = 701) and a group of patients with pathologies linked to low grade inflammation or alteration of carbohydrate metabolism (n = 1299). All samples were analysed for the presence of TTV, TTMDV and TTMV DNA by hemi-nested PCR. RESULTS: The prevalence of TTV, TTMDV and TTMV in the studied population was 68.2, 54.4%, respectively 40.1%, lower than the recent reports from other geographic regions. The three viral species were significantly more frequent in the group of patients compared to the healthy subjects and were associated with type 2 diabetes mellitus. The presence of anelloviral DNA was also associated with medical procedures (e.g. haemodialysis/transfusions, surgical procedures) and previous hepatitis A virus infection. Lifestyle choices related to alcohol consumption, smoking, physical activity and living environment were not associated with differences in distribution of the three viruses. CONCLUSION: Further evidence is needed to establish a correlation between infection with human anelloviruses and a pathology or group of pathologies.