[Comparison between the LightCycler CMV Quant Kit (Roche Diagnostics) with a standardized in-house Taqman assay for cytomegalovirus blood viral load quantification].
The broad use of cytomegalovirus (CMV) viral load quantification in blood to follow immunosuppressed patients need standardized assays. Choice of whole blood allows follow-up for several viruses and simplifies pretreatment and storage of samples.


METHODS
We therefore evaluated the LightCycler CMV Quant Kit (Roche Diagnostics) assay on whole blood after a manual extraction (High Pure viral nucleic acid kit, Roche Diagnostics), using as a reference an in-house Taqman assay (LC1UL83) which has been validated in various clinical situations. A panel obtained by serial dilutions of a virion stock in CMV whole blood, a commercial plasma quality control (VQC, Argène, France) crude or diluted in whole blood, infected cells extracts and 46 clinical samples from transplanted patients were tested simultaneously by both techniques.


RESULTS
For plasma quality controls, both PCR assays are correlated VQC (R(2)=0.93). On whole blood or infected cells dilutions, correlation shows an overestimation by the LC1UL83 assay (mean 1.2 log copies/ml) over 3 log though R(2)=0.94. Results with CMV Quant Kit are closer to expected values. Results on clinical samples are close to quality controls with a lower variation of quantification (0.76 log copies/ml).


CONCLUSIONS
CMV Quant Kit performs well when compared with a clinically validated PCR. Quality control results showed discrepancies between plasma and whole blood, demonstrating the need for whole blood standardized panels to compare the methods. This underlines the need to follow a patient with the same technique during his follow-up.
Alain
S
S
Centre national de référence des cytomégalovirus, CHU de Limoges, 2, avenue M.-L.-King, 87000 Limoges, France. sophie.alain@unilim.fr
Lachaise
V
V
Hantz
S
S
Denis
F
F
D001769:Blood / Q000821:virology; D003199:Computer Systems; D003587:Cytomegalovirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000097:blood / Q000821:virology*; D004279:DNA, Viral / Q000097:blood*; D005838:Genotype; D006801:Humans; D016377:Organ Transplantation; D010750:Phosphoproteins / Q000097:blood; D010949:Plasma / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011183:Postoperative Complications / Q000097:blood / Q000821:virology; D011786:Quality Control; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019914:Taq Polymerase; D019562:Viral Load; D014763:Viral Matrix Proteins / Q000097:blood; D014766:Viremia / Q000821:virology*
D004279:DNA, Viral; D010750:Phosphoproteins; D011933:Reagent Kits, Diagnostic; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D019914:Taq Polymerase