Prevalence of transfusion transmitted virus infection and its effect on renal graft survival in renal transplant recipients

Torque teno virus viremia and QuantiFERON®-CMV assay in prediction of cytomegalovirus reactivation in R+ kidney transplant recipients

Introduction

Cytomegalovirus (CMV) is the most frequent infectious complication following solid organ transplantation. Torque teno viruses (TTV) viremia has been proposed as a biomarker of functional immunity in the management of kidney transplant recipients (KTR). The QuantiFERON^®-CMV (QF-CMV) is a commercially available assay that allows the assessment of CD8⁺ T-cell responses in routine diagnostic laboratories.

Methods

In a prospective national multicenter cohort of 64 CMV-seropositive (R+) KTR, we analyzed the value of TTV load and the two markers of the QF-CMV assay [QF-Ag (CMV-specific T-cell responses) and QF-Mg (overall T-cell responses)], alone and in combination, in prediction of CMV reactivation (≥3 log₁₀ IU/ ml) in the first post-transplant year. We compared previously published cut-offs and specific cut-offs optimized from ROC curves for our population.

Results

Using the conventional cut-off (3.45 log₁₀ copies/ml), TTV load at D0 [inclusion visit on the day of transplantation before induction (D0)], or at M1 (1-month post-transplant visit) perform better in predicting CMV viremia control than CMV reactivation. Survival analyses suggest a better performance of our optimized TTV cut-offs (3.78 log₁₀ copies/ml at D0 and 4.23 log₁₀ copies/ml at M1) for risk stratification of CMV reactivation in our R+ KTR cohort. The QF-CMV (QF-Ag = 0.2 IU/ml, and QF-Mg = 0.5 IU/ml) also appears to better predict CMV viremia control than CMV reactivation. Moreover, survival analyses suggest that the QF-Mg would perform better than the QF-Ag in stratifying the risk of CMV reactivation. The use of our optimized QF-Mg cut-off (1.27 IU/ml) at M1 further improved risk stratification of CMV reactivation. Using conventional cut-offs, the combination of TTV load and QF-Ag or TTV load and QF-Mg did not improve prediction of CMV viremia control compared to separate analysis of each marker but resulted in an increase of positive predictive values. The use of our cut-offs slightly improved risk prediction of CMV reactivation.

Conclusion

The combination of TTV load and QF-Ag or TTV load and QF-Mg could be useful in stratifying the risk of CMV reactivation in R+ KTR during the first post-transplant year and thereby have an impact on the duration of prophylaxis in these patients.

Clinical trial registration

ClinicalTrials.gov registry, identifier NCT02064699.

Development of a standardized real time PCR for Torque teno viruses (TTV) viral load detection and quantification: A new tool for immune monitoring

BACKGROUND

Torque teno viruses (TTV) are small DNA viruses whose replication is closely linked to immune status. A growing number of publications underlined the potential of TTV viral load as an indicator of immunosuppression.

OBJECTIVES

To demonstrate the analytical performance of the first standardized RUO (Research Use Only) assay to detect and quantify human TTV DNA in whole blood and plasma.

STUDY DESIGN

We established analytical performances for TTV load measurement in various populations. The TTV kinetics were followed in kidney recipients. TTV viral load was analyzed on whole blood samples from 42 kidney recipients follow-up, 53 kidney deceased donors and 31 healthy volunteers.

RESULTS

The qPCR TTV assay detects the most prevalent human TTV genotypes and does not cross react with other viruses. Limit of detection was 2.2 log₁₀ copies/mL in whole blood and plasma, linearity and precision were demonstrated over the range 1.61 to 10.61 log₁₀ copies/mL in whole blood. Prevalence of TTV DNA in blood differed significantly among groups: 45% in healthy volunteers, 74% in donors and 83% in kidney recipients. In kidney recipients, early TTV kinetics were comparable to those previously observed with in-house assays in other transplant settings: viral load increased from an average of 4.3 log₁₀ to 7.9 log₁₀ copies/mL within the first 75 days post transplantation.

CONCLUSION

This TTV assay showed high analytical sensitivity, specificity, linearity and precision. It is a useful standardized tool to further evaluate TTV load as a biomarker of immune status that could improve individual treatment strategy.

Reduced maternal levels of common viruses during pregnancy predict offspring psychosis: potential role of enhanced maternal immune activity?

Viral infections during the prenatal or early childhood periods are one of the environmental factors which might play an etiological role in psychoses. Several studies report higher antibody levels against viruses during pregnancy in blood of mothers of offspring with psychotic disorders, but the presence of such viruses has never been demonstrated. The goal of this study was to investigate the potential association between viral infections during pregnancy and progeny with psychotic disorders and, for this purpose, we performed a nested case-control study involving pregnant mothers of offspring with schizophrenia or bipolar disorder with psychotic features (cases, N=43) and pregnant women with healthy offspring (controls, N=95). Since several potential viral candidates have been suggested in prior work, a broad-spectrum virus detection system was necessary. A metagenomic analysis performed with the virus discovery method VIDISCA-454 revealed only common blood-associated viruses in all cohorts. However, a significantly lower viral prevalence was detected in the group of cases and in the sub-population of pregnant mothers of offspring with schizophrenia (p<0.05). Consistent with the existing inverse correlation between the level of these viruses and the immunocompetence of an individual, we hypothesized the presence of a higher immune activity during pregnancy in mothers whose offspring later develop a psychotic disorder as compared to controls. Combining our results with previously available literature data on antibody levels during the gestation period suggests that a more prominent maternal immune activity can be considered a risk factor for developing psychosis.

Emerging viral diseases in kidney transplant recipients

Viruses are the most important cause of infections and a major source of mortality in Kidney Transplant Recipients (KTRs). These patients may acquire viral infections through exogenous routes including community exposure, donor organs, and blood products or by endogenous reactivation of latent viruses. Beside major opportunistic infections due to CMV and EBV and viral hepatitis B and C, several viral diseases have recently emerged in KTRs. New medical practices or technologies, implementation of new diagnostic tools, and improved medical information have contributed to the emergence of these viral diseases in this special population. The purpose of this review is to summarize the current knowledge on emerging viral diseases and newly discovered viruses in KTRs over the last two decades. We identified viruses in the field of KT that had shown the greatest increase in numbers of citations in the NCBI PubMed database. BKV was the most cited in the literature and linked to an emerging disease that represents a great clinical concern in KTRs. HHV-8, PVB19, WNV, JCV, H1N1 influenza virus A, HEV, and GB virus were the main other emerging viruses. Excluding HHV8, newly discovered viruses have been infrequently linked to clinical diseases in KTRs. Nonetheless, pathogenicity can emerge long after the discovery of the causative agent, as has been the case for BKV. Overall, antiviral treatments are very limited, and reducing immunosuppressive therapy remains the cornerstone of management.

Human anelloviruses and the central nervous system

Torque teno virus and related anelloviruses are a recent addition to the list of agents that cause chronic productive infections and high levels of plasma viraemia in humans. Many aspects of the natural history and pathogenesis of these under many respects surprising viruses are still poorly understood. In this review, we briefly outline the general properties of anelloviruses, examine what is currently known about the interactions they establish with the central nervous system (CNS), and discuss the possible pathological consequences.

Hepatitis C virus infection in dialysis patients

Hepatitis C virus (HCV) infection is a global health problem, common worldwide, leading to acute and chronic hepatitis and its consequences of hepatocirrhosis and hepatocellular carcinoma. Patients on hemodialysis belong to the high-risk group of HCV infection. The prevalence of HCV infection in dialysis patients ranges from 4% to more than 70% in some countries. The main reasons for such a high incidence of infections are a high prevalence of HCV infection in the general population, lack of standard infection precautions and effective vaccination, inadequate disinfection procedures of dialysis machines and other medical equipment, as well as spread of infection from patient to patient, especially in dialytic centers with a high percentage of infected patients. The diagnostic procedures useful in the evaluation of HCV infection are detection of anti-HCV antibodies, identification of HCV RNA, counts of virus copies, and identification of its genome. From the 6 major genotypes and multiple subtypes of the HCV, genotypes 1a and 1b are the most common in Europe and Japan, and 1b is responsible for more severe liver disease and aggressive course leading to liver fibrosis. Antiviral therapy of HCV+ dialysis patients with interferon-alpha (INF-alpha) gives slightly better results than in the general population, but is poorly tolerated and associated with side effects. Although ribavirin in not recommended for dialysis patients, the addition of small doses of this compound to pegylated INF is discussed, especially for patients in whom previous infection treatment failed.

Outcome of Renal Allograft in Turkish Patients With Pretransplantation Hepatitis C Virus Infection

BACKGROUND

The aim of the present study was to investigate the impact of hepatitis C virus (HCV) infection on the long-term survival of renal transplant recipients.

METHODS

Outcomes and survivals among 325 patients who received renal allografts from July 1991 to September 2005 were compared between those known to have pretransplantation HCV infection (Group I, HCV+ group, n = 33) versus a matched cohort of those without this infection (Group II, HCV- control group, n = 33). Allograft performance, liver function, cholesterol, and glucose levels were determined both at transplantation and at a mean of postgrafting year 8. A one-way analysis of variance (ANOVA) statistical method was used for multivariate analysis.

RESULTS

Thirty-three patients (10.15%, 19 women and 14 men) were positive for HCV antibody. The mean follow-up period was 8 years (range, 0.5-14 years). The mean survival rates were similar in Groups I and II (96.6% and, 100%, respectively). Although the allograft survival rate was lower in Group I (84.8% vs 90.9%), the rejection rate among the HCV- group was 6%; only 1 patient died of hepatic failure. In spite of a significant rise in both total and direct bilirubin values (P < .01) in both groups, we failed to observe an adverse effect on graft survival. A significant rise in the fasting glucose level was seen in both HCV+ and HCV- patients.

CONCLUSIONS

Chronic HCV infection before transplantation did not have a significant impact on graft survival or mortality compared with noninfected patients.

[Transfusion-transmitted virus (TTV) and renal failure]

In 1997, a new DNA virus, designated TTV "Transfusion Transmitted Virus", was isolated and seemed to be associated with non A-G post-transfusion hepatitis. The virus infects mainly patients at risk for parenteral exposure and hence, prone to develop chronic liver disease, as well as healthy populations worldwide. Few reports, however, have been published on the epidemiology and potential significance of TTV infection in patients with renal disease. This paper reviews, characterization of the virus, the history of its discovery, taxonomy and identification. Current status of TTV infection in patients with renal diseases are also summarised.