Comparison of two commercial quantitative PCR assays and correlation with the first WHO International Standard for human CMV.

Comparability between CMV assays could be facilitated by the first WHO International Standard for human CMV (standard). Standard dilutions were submitted to nucleic acid extraction with Versant kPCR Molecular systems SP or MagNA Pure LC System followed by the kPCR PLX™ CMV DNA (kPCR) or the CMV R-gene™ assay (R-gene), respectively; 139 clinical specimens were tested. Both assays correlated well with the standard (R2 > 0.96) and a matrix effect was observed. Quantitative results correlated reasonably between both assays for whole blood (R2 = 0.79) and well for other specimen types (R2 = 0.93). Quantification differences were within one log10 of the averaged log10 results for 25/27 blood specimens and for 32/33 other specimens. Calibration to the standard did not increase this percentage. In conclusion, results of both assays showed reasonable correlation with each other and good correlation with the standard. Calibration to the standard did not improve comparability of quantitative results.

Comparison of two commercial quantitative PCR assays for EBV DNA detection and their correlation with the first WHO International Standard for EBV.

PURPOSE: There are few data on the performance of automated Epstein-Barr virus (EBV) PCR assays. This study compared EBV quantification for the kPCR PLX EBV DNA (kPCR; Siemens, France) and the EBV R-gene (R-gene; Argene, Biomerieux, France) assays and their correlation with the World Health Organization (WHO) standard. METHODOLOGY: WHO International Standard for EBV (WHO standard) dilution panels in different matrices were submitted to nucleic acid extraction with Versant kPCR Molecular Systems SP followed by the kPCR assay, or to nucleic acid extraction with the MagNA Pure LC System or NucliSENS easyMag followed by the R-gene assay. Seventy-four clinical specimens were tested in both assays. Bland-Altman analysis and linear regression analysis were performed. RESULTS: The correlation between the WHO standard diluted in different matrices and the R-gene and kPCR assays was good (R2 >0.96 and R2 >0.92, respectively). A matrix effect was observed. The correlation of quantitative results between both assays yielded a coefficient of determination R2 higher than 0.74. The quantification differences were within one log10 of the averaged results for 34 of the 38 specimens (89 %). Calibration to the WHO standard did not increase the comparability of quantitative results. CONCLUSIONS: The quantitative results of both assays showed reasonable correlation with each other and a good correlation with the WHO standard.