Comparative quantitation of cytomegalovirus (CMV) DNA in solid organ transplant recipients with CMV infection by using two high-throughput automated systems

Abstract

Cytomegalovirus (CMV) DNA quantitation in clinical specimens is progressively becoming a cornerstone in the diagnosis and management of CMV infection in the immunocompromised host. We evaluated two automated and reproducible PCR tests, the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and the COBAS AMPLICOR CMV Monitor (Roche Diagnostics, Pleasanton, Calif.), for the detection of CMV DNA in blood samples from transplant recipients with CMV infection as determined by shell vial culture. Following a log transformation analysis, the mean CMV DNA in plasma (PL), whole blood (WB), peripheral blood leukocytes (PBL), and peripheral blood mononuclear cells (PBMC) using the LightCycler was 6.79 copies per ml, 7.23 copies per ml, 6.38 copies per 2 x 10(6) cells, and 6.27 copies per 2 x 10(6) cells, respectively. This compares to 7.86 copies per ml, 8.37 copies per ml, 7.59 copies per 2 x 10(6) cells, and 7.44 copies per 2 x 10(6) cells, respectively, using COBAS AMPLICOR CMV Monitor. While higher CMV DNA levels were observed for the various blood compartments analyzed using COBAS AMPLICOR CMV Monitor, a high degree of correlation was evident between the two automated systems (jackknife correlation r = PL 0.77 [95% confidence interval (CI); 0.64, 0.90], WB 0.77 [95% CI; 0.62, 0.92], PBL 0.77 [95% CI; 0.67, 0.88], and PBMC 0.81 [95% CI; 0.72, 0.89], all P < 0.001). Therefore, we conclude that either automated diagnostic system is accurate for CMV DNA quantitation.

FIG. 1

Comparison between the LightCycler and COBAS AMPLICOR CMV Monitor mean CMV DNA levels in WB during CMV infection and/or disease and its treatment. Note: i.v. GCV was administered immediately following the collection of the first blood sample for CMV DNA quantitation and for a duration of 14 days.

FIG. 2

Jackknife analysis of correlation of the CMV DNA levels in different blood compartments (PL [A], WB [B], PBL [C], and PBMC [D]) as assessed by the LightCycler and COBAS AMPLICOR CMV Monitor. Note: Each point in the graphs represents an individual sample that was tested for CMV DNA using both the LightCycler (LC) and COBAS AMPLICOR CMV Monitor (COBAS). The x axis represents the log values of CMV DNA per milliliter of WB or PL and per 2 × 10⁶ PBL or PBMC as assessed by the COBAS, and the y axis represents the log values of CMV DNA per milliliter of WB or PL and per 2 × 10⁶ PBL or PBMC as assessed by the LC.