PERFORMANCE OF THE COBAS AMPLIPREP/COBAS TAQMAN (CAP/CTM) REAL-TIME POLYMERASE CHAIN REACTION ASSAY FOR HEPATITIS B VIRUS DNA QUANTIFICATION

French National Reference Center for Viral Hepatitis B, C and delta, Department of Virology, Hôpital Henri Mondor, Université Paris 12, Créteil, France; INSERM U841, Créteil, France; French National Reference Center for Hepatitis B, C and delta in Blood Transfusion, Institut National de la Transfusion Sanguine, Paris, France

^* To whom correspondence should be addressed. Email: jean-michel.pawlotsky{at}hmn.aphp.fr.

	Abstract

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 polymerase chain reaction (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: 98.1-100%). Intra-assay coefficients of variation ranged from 0.22% to 2.68% and inter-assay coefficients of variation from 1.31% to 4.13%. Quantification was linear over the full dynamic range of quantification of the assay (1.7 to 8.0 Log₁₀ international units (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 Log₁₀ 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 accurately quantifies HBV DNA 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 then retested. Broad use of fully automated real-time PCR assays should improve the management of patients with chronic HBV infection.