Quantitation of Cytomegalovirus DNA Load in Dried Blood Spots Correlates Well with Plasma Viral Load

Abstract

An assay to accurately quantitate cytomegalovirus (CMV) load in finger-stick-collected dried blood spots (DBS) could potentially be useful for field studies or for analyzing patient self-collected specimens. We therefore assessed CMV DNA load in paired venipuncture-collected plasma samples and finger-stick DBS, using a previously validated quantitative PCR assay. Assay variability, sensitivity, and changes in viral load during antiviral therapy in finger-stick DBS were compared to the reference plasma quantitative PCR assay, using 106 prospectively collected pairs of finger-stick DBS and plasma samples from 35 solid-organ transplant (SOT) patients. The DBS assay showed good agreement with the reference plasma viral load assay on the log 10 scale (Pearson correlation coefficient, 0.92; P < 0.001). The 95% limit of detection of the DBS assay was estimated at 2,700 plasma copies/ml (675 plasma IU/ml). In 94% (76/81) of paired DBS and plasma samples above the limit of detection, the difference in CMV load was <1 log 10 . CMV viral load changes during antiviral treatment were comparable in plasma and DBS. We conclude that finger-stick DBS provides a convenient sample type for quantitation of CMV load that correlates well with plasma levels. Future studies to optimize and evaluate this methodology for patient self-collected samples are warranted.A ssessment of cytomegalovirus (CMV) load in blood has been shown to be clinically useful in various patient populations (1). In transplant recipients, quantitation of CMV load in blood (plasma, whole blood, peripheral blood mononuclear cells, or lymphocytes) is commonly used for diagnosis of CMV disease, as a marker for initiating antiviral therapy in patients receiving preemptive therapy, and for monitoring response to therapy (1). Typically, CMV quantitation is performed using blood collected by phlebotomy (venipuncture). However, this approach requires that patients have access to facilities and personnel where phlebotomy can be performed. This can be a limitation in situations where such access is not readily available (field studies in resourcelimited settings or for patients who live long distances from medical facilities).Several previous studies described the use of dried blood spots (DBS) for detection of CMV (2-12). However, most of these prior studies using DBS for detection of CMV focused on children with congenital CMV infection, where quantitation and monitoring of viral load over time are not routinely performed. Other limitations of prior studies have included relatively small numbers of patients, use of systematically spotted cards with known pipetted venipuncture-collected blood volumes (rather than utilizing actual finger-stick blood, in which precise volumes are not known and homogeneity of blood on cards is not ensured), lack of comparison with concomitantly collected blood samples, or lack of serially collected specimens for assessment of viral load changes during treatment. To our knowledge, there are no prior published studies that have specifically fo...

Incidence of Cytomegalovirus disease and viral replication kinetics in seropositive liver transplant recipients managed under preemptive therapy in a tertiary-care center in Mexico City: a retrospective cohort study

“…Preemptive therapy is logistically challenging. Novel platforms of viral load measurement such as dried-blood spots (DBS) have the potential to ease the burden of monitoring for patients and transplant centres [ 11 ].…”

Clinical characteristics and outcomes of late‐onset BK virus nephropathy in kidney and kidney‐pancreas transplant recipients

“…One of the challenges of this approach is adherence to screening late in the post‐transplant period, when patients might not be motivated to undergo frequent laboratory monitoring. Newer technologies such as self‐collected dried blood (or urine spots) that have been developed for other detection and quantitation of viral infections in transplant recipients might offer more convenient and feasible options for BKPyV monitoring in the future, and should be specifically studied.…”

An artesunate-containing antimalarial treatment regimen did not suppress cytomegalovirus viremia

“…However, CMV PCR results from DBS and plasma samples are highly correlated in transplant patients, including during ganciclovir treatment. 16 Finally, the effects of artesunate on CMV infection might differ between children with malaria and other populations, such as transplant patients. Our results do not preclude the possibility that artesunate may have a role in the treatment of CMV infection, but they strongly suggest that longer courses and/or higher doses than those used for malaria treatment are required to observe an effect on CMV viremia.…”

“…15, 16 The lower limit of detection was approximately 3 copies of CMV per reaction. Multiple negative controls were included in each PCR run.…”