Real-time PCR per HBV DNA: valutazione del nuovo sistema automatizzato COBAS AMPLIPREP™/COBAS TAQMAN™ HBV

Success of antiviral therapy for chronic hepatitis B is supported by highly sensitive PCR-based assays for Hepatitis B virus (HBV) DNA. Nucleic acid extraction from biologic specimens is technically demanding and reliable PCR results depend it. Performances of the fully automatic system COBAS AmpliPrep™/COBAS TaqMan™ 48 (CAP/CTM) (Roche, Branchburg, NJ) for HBV DNA extraction and real -time PCR quantification were assessed and compared with the end-point PCR COBAS AMPLICOR HBV Monitor (CAHBM, Roche). Analytical evaluation with a proficiency panel showed that CAP/CTM quantitated HBV DNA levels in one single run over a wide dynamic range (7 logs) with a close correlation between expected and observed values (r=0.976, interassay variability below 5%). Clinical evaluation as tested with samples from 92 HBsAg-positive patients, demonstrated excellent correlation with CAHBM (r=0.966, mean difference in quantitation: 0.36 log10 IU/ml). CAP/CTM detected 10% more viremic patients and longer period of residual viremia in those on therapy. In lamivudine (LAM)-resistant patients, reduction of HBV DNA after 12 months of Adefovir (ADF) was higher in the combination (LAM+ADF) schedule than in ADF monotherapy (5.1 vs. 3.5 logs) suggesting a benefit in continuing LAM. In conclusion,CAP/CTM can improve the management of HBV infection, the assessment of antiviral therapy and drug resistance, supporting further insights in the emerging area of drug resistance.