TABLE 3.

Summary of molecular quantitative CMV assays

Assay	Turnaround time (h)	Sample processing (blood)	Reporting of results	Batch testing	Lower limit of detection	Dynamic range for quantitation	Reproducibility (coefficient of variation)	Equipment and facilities needed	Advantages	Disadvantages
bDNA assay	24	Recovery of ≥2 × 106 PMN	No. of CMV copies per ml	≤41 specimens (+3 controls) (plate format)	4 × 103 copies/106 leukocytes (version 1); 9 × 102 copies/106 leukocytes (version 2)	3 log10 (36)	Intra- and interassay variabilities of 5.9 and 9.7% (high copy number) and 24.9 and 26.2% (low copy number) (121)	Quantiplex bDNA System	High reproducibility	Requires large number of PMNs; long initial incubation period (16–18 h)
Hybrid capture DNA assay	6	Whole blood (3.5 ml); delayed processing possible	pg of CMV DNA or no. of CMV copies per ml	≤48 specimens (+12 controls) per quantitative run (tube format)	5 × 103 copies/ml of whole blood (version 1); 7 × 102 copies/ml of whole blood (version 2)	2 log10 (16.6–1,660 pg of DNA [version 1]; 2.1–830 pg of DNA [version 2])	Intra- and interassay variabilities of 17.8 and 16.3%, respectively (115)	Luminometer	Rapidity of procedure (6 h); simple sample processing	Many controls required for quantitative testing
PCR assays	24–48a	Variable (PMN or plasma); delayed processing possible	No. of CMV copies per μl of plasma, per 105 PMN, or per μg of DNA	Variable (e.g., ≤21 samples and 3 controls per run in plate format for AMPLICOR MONITOR CMV test)	Variable (e.g., 5 × 102 [qualitative], 2.5 × 103 [quantitative] per ml of plasma [162]; 1 × 103 [qualitative], 4 × 102 [quantitative] per ml of plasma [AMPLICOR CMV test] [167])	2–3 log10 (23)	No data; higher if competitive assay used	Thermal cycler; detection devices (spectrophotometer, phosphorimager, etc.)	High sensitivity	Amplicon contamination; not well standardized; time-consuming

^aAmplification and detection.