Nation-wide measure of variability in HCMV, EBV and BKV DNA quantification among centers involved in monitoring transplanted patients

Quantification of low-level human cytomegalovirus and Epstein-Barr virus DNAemia by digital PCR

BACKGROUND

Digital PCR (dPCR) can quantify cell-free viral DNA (DNAemia), a biomarker of active viral infection. To accelerate epidemiologic investigation into low-level viral reactivation in chronic disease, we have evaluated the performance of dPCR to detect cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNAemia across platforms and blood matrices.

METHODS

The droplet-based (BioRad) dPCR platform performance was compared to chip-based (BioMark), and assay validation followed dMIQE guidelines. CMV and EBV DNA reference materials were spiked into known negative plasma and serum samples. In addition, two independent cohorts of ovarian cancer patients were evaluated for viral DNAemia (n = 65 serum and 79 plasma samples).

RESULTS

The limit of quantification (LOQ) was at or slightly above 100 copies/mL for both instruments: 105-135 copies/mL for droplet-based detection and 100 copies/mL for chip-based detection. DNAemia in serum had a slightly lower LOQ (105-110 copies/mL) compared to plasma (LOQ; 115-135 copies/mL). The variation (CV) coefficients for each assay and machine were less than 5 %. In patient samples, CVs ranged from 4.5 - 7.4 % and were similar for cell-free DNA derived from serum or plasma. There was good correlation between DNAemia measurements in patient samples across dPCR platforms (r > 0.90 for each assay and matrix).

CONCLUSION

dPCR can quantify low-level herpes virus DNAemia with CVs below 8 %. Our results indicate that using serum-derived cell-free DNA and droplet-based dPCR is optimal for quantitating low-level viral DNAemia; however, plasma and chip-based approaches are acceptable alternatives and suitable for epidemiologic investigation.

The IPTA Nashville Consensus Conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: III - Consensus guidelines for Epstein-Barr virus load and other biomarker monitoring

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders after solid organ transplantation in children. In this report from the Viral Load and Biomarker Monitoring Working Group, we reviewed the existing literature regarding the role of Epstein-Barr viral load and other biomarkers in peripheral blood for predicting the development of PTLD, for PTLD diagnosis, and for monitoring of response to treatment. Key recommendations from the group highlighted the strong recommendation for use of the term EBV DNAemia instead of "viremia" to describe EBV DNA levels in peripheral blood as well as concerns with comparison of EBV DNAemia measurement results performed at different institutions even when tests are calibrated using the WHO international standard. The working group concluded that either whole blood or plasma could be used as matrices for EBV DNA measurement; optimal specimen type may be clinical context dependent. Whole blood testing has some advantages for surveillance to inform pre-emptive interventions while plasma testing may be preferred in the setting of clinical symptoms and treatment monitoring. However, EBV DNAemia testing alone was not recommended for PTLD diagnosis. Quantitative EBV DNAemia surveillance to identify patients at risk for PTLD and to inform pre-emptive interventions in patients who are EBV seronegative pre-transplant was recommended. In contrast, with the exception of intestinal transplant recipients or those with recent primary EBV infection prior to SOT, surveillance was not recommended in pediatric SOT recipients EBV seropositive pre-transplant. Implications of viral load kinetic parameters including peak load and viral set point on pre-emptive PTLD prevention monitoring algorithms were discussed. Use of additional markers, including measurements of EBV specific cell mediated immunity was discussed but not recommended though the importance of obtaining additional data from prospective multicenter studies was highlighted as a key research priority.

Herpes Virus Infection in Lung Transplantation: Diagnosis, Treatment and Prevention Strategies

Lung transplantation is an ultimate treatment option for some end-stage lung diseases; due to the intense immunosuppression needed to reduce the risk of developing acute and chronic allograft failure, infectious complications are highly incident. Viral infections represent nearly 30% of all infectious complications, with herpes viruses playing an important role in the development of acute and chronic diseases. Among them, cytomegalovirus (CMV) is a major cause of morbidity and mortality, being associated with an increased risk of chronic lung allograft failure. Epstein-Barr virus (EBV) is associated with transformation of infected B cells with the development of post-transplantation lymphoproliferative disorders (PTLDs). Similarly, herpes simplex virus (HSV), varicella zoster virus and human herpesviruses 6 and 7 can also be responsible for acute manifestations in lung transplant patients. During these last years, new, highly sensitive and specific diagnostic tests have been developed, and preventive and prophylactic strategies have been studied aiming to reduce and prevent the incidence of these viral infections. In this narrative review, we explore epidemiology, diagnosis and treatment options for more frequent herpes virus infections in lung transplant patients.

Performance Evaluation of the Fully Automated NeuMoDx RT-PCR Platform for the Quantification of CMV and EBV DNA in EDTA Plasma: Implications for Clinical Management and Establishment of a Conversion Formula

The NeuMoDx96 platform is a fully automated real-time PCR (RT-PCR) system. To provide continued testing quality with the introduction of new assays, the primary aim of this study was to evaluate the analytical and clinical performance of the NeuMoDx platform for the detection and quantification of CMV and EBV DNA in EDTA plasma. As no conversion from log₁₀ international units per milliliter to copies per milliliter was provided, the secondary aim was to calculate and establish a conversion factor for the output of results in copies per milliliter for CMV and EBV. Archived ETDA plasma samples (cytomegalovirus [CMV], n = 290; Ebstein-Barr virus [EBV], n = 254) were used to evaluate the analytical performance of the NeuMoDx96 platform against the routine real-time quantitative PCR (qPCR) assays. Additionally, the first WHO international standards (WHO-IS) for CMV (n = 70) and EBV (n = 72) were used for the calculation of the intra- and interassay variation. WHO-IS qualitative agreement between the assays was 100%. Intra-assay variability was low for both CMV assays (coefficient of variation [CV], phosphate-buffered saline [PBS], 3 log₁₀ IU/mL NeuMoDx, 3.67%; Abbott RealTime, CMV, 3.35%) and NeuMoDx EBV assay (CV, PBS, 3 log₁₀ IU/mL, 3.05%) but high for the Altona EBV assay (CV, PBS, 3 log₁₀ IU/mL, 26.13%). The overall qualitative concordance in clinical samples was 96.8% (270/279) for CMV and 96.7% (237/245) for EBV. The mean difference between the assays was -0.2 log₁₀ IU/mL (CMV) and -0.18 log₁₀ IU/mL (EBV). High qualitative concordance and a significant correlation of quantitative values for both assays make NeuMoDx CMV and EBV assays suitable for routine diagnostic testing. The new RT-PCR system and conversion formulas to report results in copies per milliliter are now applied in clinical routine testing. IMPORTANCE Clinical management of solid organ transplant (SOT) patients requires the careful monitoring of immunosuppression and viral infection or reactivation. qPCR is the gold standard for the detection and quantification of very small amounts of viral DNA and allows for an early assessment of viral load kinetics. The tested NeuMoDx 96 platform provides faster results than the previously used RT-PCR workflows for CMV (Abbott m2000 and RealTime CMV assay) and EBV (LightCycler 480 II, Roche high pure extraction, and Altona RealStar EBV assay) DNA detection. The implemented conversion formulas allow the continued reporting in clinically established copies per milliliter, important for long-term care of SOT patients.

Kinetics of cytomegalovirus and Epstein-Barr virus DNA in whole blood and plasma of kidney transplant recipients: Implications on management strategies

This retrospective multicenter cohort study investigated the kinetics (ascending and descending phases) of cytomegalovirus (CMV) and Epstein-Barr virus (EBV)-DNA in whole blood (WB) and plasma samples collected from adult kidney transplant (KT) recipients. CMV-DNA kinetics according to antiviral therapy were investigated. Three hundred twenty-eight paired samples from 42 episodes of CMV infection and 157 paired samples from 26 episodes of EBV infection were analyzed by a single commercial molecular method approved by regulatory agencies for both matrices. CMV-DNAemia followed different kinetics in WB and plasma. In the descending phase of infection, a slower decay of viral load and a higher percentage of CMV-DNA positive samples were observed in plasma versus WB. In the 72.4% of patients receiving antiviral therapy, monitoring with plasma CMV-DNAemia versus WB CMV-DNAemia could delay treatment interruption by 7–14 days. Discontinuation of therapy based on WB monitoring did not result in relapsed infection in any patients. Highly different EBV-DNA kinetics in WB and plasma were observed due to lower positivity in plasma; EBV positive samples with a quantitative result in both blood compartments were observed in only 11.5% of cases. Our results emphasize the potential role of WB as specimen type for post-KT surveillance of both infections for disease prevention and management.

CMV infection management in transplant patients in Italy

Transplant represents an effective strategy in the management of chronic organ dysfunction. Nonetheless, life threatening risks remain, especially in the post-transplant; among them, human cytomegalovirus (CMV) is a major concern, currently causing active infections in at least one-third of transplant recipients. Microbiologist and transplant scientific societies redefined guidance on CMV disease prevention and the best use for universal prophylaxis and pre-emptive virological monitoring. Developments in molecular diagnostic supported the spread of the pre-emptive strategy, and quantitative Real Time-PCR assays has unravelled the potential of viral load measurement as a predictor of the infection development in CMV post-transplant management. However, despite the WHO 1st CMV International Standard, the standardization of diagnostic and clinical practice has been limited by the absence of algorithms for calculating conversion factor to International Units and the lack of shared monitoring procedure, both at national and international level. At a regional level, the Italian scientific societies, AMCLI (Italian Clinical Microbiologist Association), SITO (Organ Transplant Italian Society), GITMO (Italian Group for Bone Marrow Transplant), recently tried to define a consensus for post-transplant monitoring. The concerted practice encompasses molecular quantitative PCR assays technical aspects and endorses the relevance of immunologic monitoring for improvement in patient risk stratification and prognosis. Here, we provide an overview of the state of the art of CMV management strategies, with a specific focus on the clinical practices and on the scientific societies' initiatives that aim to implement international standardization guidelines at a national level.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.