DETERMINATION OF CMV VIRAL LOAD BY ARTUS (QIAGEN) CMV REAL-TIME PCR ANALYTE-SPECIFIC REAGENT USING LIGHTCYCLER

Background: Infection with CMV is a major cause of disease and death in immunocompromised individuals including: neonates, AIDS patients, and organ and bone marrow transplant recipients.

Aim: The aim of this study was to validate the performance of the Artus CMV LightCycler Analyte-Specific Reagnet (CMV LC ASR) for quantitative detection of CMV from plasma specimens.

Methods: Specimens were extracted by Qiagen QIAamp DNA Mini kit, then amplified and detected on the Roche LightCycler using the Artus CMV LC ASR. Analytical Sensitivity, Analytical Specificity, Precision and Accuracy were determined. Interlaboratory comparison of viral load was completed using 58 specimens. 35 of these were plasma specimens previously extracted by the Roche MagNA Pure and tested by the same ASR by another laboratory. 5 of the other laboratory’s MagNA Pure extractions were also tested. In addition, 18 plasma specimens were extracted and tested that were previously tested using the Roche Cobas Amplicor.

Results: About 2.5 copies per reaction (125 copies/ml) were reliably detected. No cross-reactivity was found for 16 organisms tested. Precision of viral load over a range of CMV standards (10⁵ to 10² copies/ml) run over a 10 day period was as follows: 9.76 % CV for 10⁵, 10.90 % CV for 10⁴, 11.52 % CV for 10³ and 9.40 % CV for 10². Accuracy of duplicate CMV quant standards at two concentrations (10⁵ and 10³ copies/ml) were run on 3 different days was as follows: 2.39 % CV for 10⁵,and 10.79 % CV for 10³. 32/40 specimens tested by Artus CMV LC ASR were comparable (log ₁₀ value differences < 0.5) to the same ASR tested by another laboratory using a different extraction method. Similarly Artus CMV LC ASR viral loads from 16/18 specimens were comparable to viral load reported by Roche Cobas Amplicor assay. 

Conclusions:  The viral load determination between different assay platforms and laboratories were comparable. The results of this study conclude that the Artus CMV LC ASR is a sensitive, specific, reliable, and easy to use ASR for CMV viral load testing from plasma.