Prediction of Cytomegalovirus (CMV) Plasma Load from Evaluation of CMV Whole-Blood Load in Samples from Renal Transplant Recipients

Abstract

In a prospective cohort of 82 renal transplant recipients, we evaluated the capacity of the cytomegalovirus (CMV) load in whole blood (WB) to predict the plasma CMV load, aiming to identify active CMV infections by using WB samples only and to deduce a WB threshold. Using quantitative real-time PCR, a total of 1,474 WB samples were assayed, of which 279 were positive for CMV, and 140 out of the 276 paired plasma samples tested positive. Thirty (36.6%) patients presented with at least one positive plasma PCR result, and 21 infection episodes (19 patients) required curative treatment (median follow-up time, 12 months). When the plasma CMV load was >500 copies/ml (n ‫؍‬ 70), more than 94% (95% confidence interval, 86.0%, 98.4%) of WB samples had >500 copies/ml. Two prediction models were built: log 10 plasma viral load (VL) was calculated as ؊0.3777 ؉ 0.9342 ؋ log 10 WB VL and as ؊0.3777 ؉ 0.8563 ؋ log 10 WB VL for patients with and without treatment, respectively. In the validation sample (578 routine samples), 77.2% of the observed and expected plasma viral loads were concordant (95% confidence intervals, 73.5 and 80.5%). According to the model, the plasma viral load was >500 copies/ml when the WB load was >3,170 or >4,000 copies/ml in patients with or without treatment, respectively. WB seems to be an appropriate candidate for routine CMV monitoring of transplant recipients by using a single assay.Cytomegalovirus (CMV) remains a major opportunistic agent among transplant recipients, due to its direct and indirect effects and despite the use of different therapeutic strategies. While detection of CMV pp65 lower matrix protein (pp65 antigen [Ag]) has been widely performed for diagnosis of CMV infection, molecular assays based on quantitative PCR are now routinely used. Indeed, sensitive assays for the early detection of CMV infection are required for monitoring of patients and are essential for timely application of antiviral therapy (6,12,16,24,25,28,37).Commercial assays were first available for quantification of CMV DNA in plasma and peripheral blood leukocytes (PBL) (23,24,28,29,36). Then real-time PCR technology became available and represented a considerable improvement, since it was simpler, cheaper, and less time-consuming. In many laboratories, CMV infection diagnosis now relies on real-time PCR

Clinical Utility of Viral Load in Management of Cytomegalovirus Infection after Solid Organ Transplantation

“…Whole blood is easy to process because it does not require complex sample preparation compared to preparation of leukocyte subpopulations (126). While studies have shown good correlations in viral load values among the various compartments, significantly higher viral load levels have been detected in whole blood (91,126,128,130,131). Accordingly, many authorities have advocated the use of whole blood for CMV DNA detection due to its higher sensitivity and ability to detect low-copynumber viral reactivation.…”

Surveillance of γδ T Cells Predicts Cytomegalovirus Infection Resolution in Kidney Transplants

“…The CMV PCR assay was used as previously described. 38 CMV DNAemia was considered positive when detectable (namely, .500 copies per 1 ml). The assay was performed one time per week for the first 3 months, one time per month between months 3 and 6, and finally, every 2 months up to 1 year.…”

Rapid quantitation of cytomegalovirus DNA in whole blood by a new molecular assay based on automated sample preparation and real-time PCR

“…There is currently no consensus on the optimal blood compartment for routine molecular CMV DNA testing. In several studies, whole blood or plasma has been found to be superior to peripheral blood leukocytes [3,5,[17][18][19][20][21][22][23].…”