Performance of the Cobas AmpliPrep/Cobas TaqMan real-time PCR assay for hepatitis B virus DNA quantification.

Hepatitis B virus (HBV) DNA quantification is used to establish the prognosis of chronic HBV-related liver disease, to identify those patients who need to be treated, and to monitor the virologic response and resistance to antiviral therapies. Real-time PCR-based assays are gradually replacing other technologies for routine quantification of HBV DNA in clinical practice. The goal of this study was to evaluate the intrinsic characteristics and clinical performance of the real-time PCR Cobas AmpliPrep/Cobas TaqMan (CAP/CTM) platform for HBV DNA quantification. Specificity was satisfactory (95% confidence interval, 98.1 to 100%). Intra-assay coefficients of variation ranged from 0.22% to 2.68%, and interassay coefficients of variation ranged from 1.31% to 4.13%. Quantification was linear over the full dynamic range of quantification of the assay (1.7 to 8.0 log(10) IU/ml) and was not affected by dilution. The assay was accurate regardless of the HBV genotype. Samples containing HBV DNA levels above 4.5 log(10) IU/ml were slightly underestimated relative to another accurate assay based on branched-DNA technology, but this is unlikely to have noteworthy clinical implications. Thus, the CAP/CTM HBV DNA assay is sensitive, specific, and reproducible, and it accurately quantifies HBV DNA levels in patients chronically infected by HBV genotypes A to F. Samples with HBV DNA concentrations above the upper limit of quantification need to be diluted and then retested. Broad use of fully automated real-time PCR assays should improve the management of patients with chronic HBV infection.