Clinical evaluation of a fully automated CMV PCR assay

BK Virus-Associated Nephropathy: Current Situation in a Resource-Limited Country

BACKGROUND

Data on BK virus-associated nephropathy (BKVAN) and treatment strategy in a resource-limited country are scarce. This study aimed to evaluate epidemiology of BKVAN and its situation in Thailand.

METHODS

A retrospective analysis was conducted among adult kidney transplant recipients at Ramathibodi Hospital from October 2011 to September 2016. Patients' demographic data, information on kidney transplantation, immunosuppressive therapy, cytomegalovirus and BK virus infections, and allograft outcomes were retrieved and analyzed.

RESULTS

This study included 623 kidney transplant recipients. Only 327 patients (52.49%) received BK virus infection screening, and 176 of 327 patients had allograft dysfunction as a trigger for screening. BKVAN was identified in 39 of 327 patients (11.93%). Deceased donor transplantation and cytomegalovirus infection were associated with a higher risk of BKVAN (odds ratio = 2.2, P = .024, 95% confidence intervals [1.1, 4.43], and odds ratio = 2.6, P = .006, 95% confidence intervals [1.29, 5.26], respectively). BKVAN patients were at significantly higher risk for allograft rejection (P < .001) and allograft failure (P = .036). At the end of the study, 4 graft losses were documented (12.12%).

CONCLUSIONS

BKVAN was associated with high rate of allograft rejection and failure. However, surveillance of its complications has been underperformed at our facility. Implementing a formal practice guideline may improve allograft outcome in resource-limited countries.

Evaluation of COBAS AmpliPrep/COBAS TaqMan CMV Test for use in hematopoietic stem cell transplant recipients

INTRODUCTION

Cytomegalovirus (CMV) is a common opportunistic infection that contributes to poor outcomes in hematopoietic stem cell transplant (HSCT) recipients. Prevention of CMV end-organ disease in allogeneic HSCT recipients is commonly achieved by preemptive antiviral therapy of asymptomatic CMV reactivation that is detected by serial nucleic acid testing (NAT). However, there was no standardized CMV NAT until the development of the World Health Organization (WHO) International Standard. Areas covered: This article provides a comprehensive review on COBAS AmpliPrep/TaqMan (CAP/CTM) CMV assay (Roche) and emphasizes the limitations in the clinical use of CMV NAT in HSCT recipients. Expert commentary: The CAP/CTM CMV Test is the first US FDA approved commercial quantitative NAT for CMV viral load monitoring of plasma samples in solid organ transplant and HSCT recipients. The CAP/CTM assay has wide linear range of DNA quantification and demonstrates colinearity to the WHO International Standard. Studies of CAP/CTM CMV assay in HSCT recipients are still limited, but are now being reported to define viral thresholds for diagnosis, surveillance and monitoring. Results from these early studies in HSCT recipients suggest that, while the WHO IS has improved the inter-laboratory result variances, there are still important factors that continue to contribute to assay variability. This lack of harmony among NAT highlights the need for further standardization.

Quantification of cytomegalovirus viral load

Cytomegalovirus (CMV), a member of the Herpesviridae family, is worldwide distributed. After the primary infection, CMV induces a latent infection with possible reactivation(s). It is responsible for severe to life-threatening diseases in immunocompromised patients and in foetuses and newborns of infected mothers. For monitoring CMV load, classical techniques based on rapid culture or pp65 antigenemia are progressively replaced by quantitative nuclear acid tests (QNAT), easier to implement and standardize. A large variety of QNAT are available from laboratory-developed assays to fully-automated commercial tests. The indications of CMV quantification include CMV infection during pregnancy and in newborns, and viral surveillance of grafted and non-grafted immunocompromised patients, patients with bowel inflammatory diseases and those hospitalised in intensive care unit. A close cooperation between virologists and clinicians is essential for optimizing the benefit of CMV DNA monitoring.

Comparative evaluation of the QIAsymphony RGQ system with the easyMAG/R-gene combination for the quantitation of cytomegalovirus DNA load in whole blood

Background

The detection of cytomegalovirus (CMV) DNA in blood is a key feature of the virological surveillance of immunocompromised patients.

Methods

The QIAsymphony RGQ system (QIAGEN S.A.S., France) combines the extraction/distribution steps on QIAsymphony SP/AS instruments with amplification on a Rotor-Gene Q RT-PCR machine. This system was compared to a strategy combining an extraction step on the NUCLISENS easyMAG platform (bioMérieux) with the CMV R-gene kit (Argene) on 100 whole blood specimens collected from immunocompromised patients of the University Hospital of Saint-Etienne, France.

Results

The overall agreement between the two strategies was 86% (kappa coefficient of 0.67); the 14 discrepant results corresponded to low DNA loads. The 62 samples found positive with both tests were correlated (Pearson r coefficient of 0.70, P < 0.01) despite an over quantitation of 0.25 log₁₀ copies/ml with the easyMAG/Argene strategy (P < 0.001). Very close results were also obtained with a commercial panel of 10 samples with CMV loads ranging from 2.36 to 6.41 log₁₀ copies/ml. The inter-run and intra-run variability was consistently lower with the QIAGEN platform.

Conclusions

These results validate the performance of the QIAsymphony RGQ system for the routine quantitation of CMV DNA. This fully-automated platform reduces the hands-on time and improves standardization, traceability and quality control assessment.

Comparative evaluation of three automated systems for DNA extraction in conjunction with three commercially available real-time PCR assays for quantitation of plasma Cytomegalovirus DNAemia in allogeneic stem cell transplant recipients

Limited data are available on the performance of different automated extraction platforms and commercially available quantitative real-time PCR (QRT-PCR) methods for the quantitation of cytomegalovirus (CMV) DNA in plasma. We compared the performance characteristics of the Abbott mSample preparation system DNA kit on the m24 SP instrument (Abbott), the High Pure viral nucleic acid kit on the COBAS AmpliPrep system (Roche), and the EZ1 Virus 2.0 kit on the BioRobot EZ1 extraction platform (Qiagen) coupled with the Abbott CMV PCR kit, the LightCycler CMV Quant kit (Roche), and the Q-CMV complete kit (Nanogen), for both plasma specimens from allogeneic stem cell transplant (Allo-SCT) recipients (n = 42) and the OptiQuant CMV DNA panel (AcroMetrix). The EZ1 system displayed the highest extraction efficiency over a wide range of CMV plasma DNA loads, followed by the m24 and the AmpliPrep methods. The Nanogen PCR assay yielded higher mean CMV plasma DNA values than the Abbott and the Roche PCR assays, regardless of the platform used for DNA extraction. Overall, the effects of the extraction method and the QRT-PCR used on CMV plasma DNA load measurements were less pronounced for specimens with high CMV DNA content (>10,000 copies/ml). The performance characteristics of the extraction methods and QRT-PCR assays evaluated herein for clinical samples were extensible at cell-based standards from AcroMetrix. In conclusion, different automated systems are not equally efficient for CMV DNA extraction from plasma specimens, and the plasma CMV DNA loads measured by commercially available QRT-PCRs can differ significantly. The above findings should be taken into consideration for the establishment of cutoff values for the initiation or cessation of preemptive antiviral therapies and for the interpretation of data from clinical studies in the Allo-SCT setting.