Abbott RealTime HBV Assay Is More Sensitive in Detection of Low Viral Load and Little Impacted by Drug Resistant Mutation in Chronic Hepatitis B Patients under Nucleot(s)ide Analogues Therapy

BACKGROUND: Selection of drug-resistant strains may lead to failure of HBV antiviral therapy. There is little information whether there is detection difference in drug resistant mutations between different viral load assays of HBV. OBJECTIVES: This study is aimed to investigate whether there is drug-resistant strains related detection difference between Abbott RealTime HBV (RealTime) and CobasAmpliPrep/CobasTaqMan HBV assays 2.0 (TaqMan). STUDY DESIGN: One hundred and thirty-four CHB patients who received HBV anti-viral therapy were enrolled. HBV virological markers were tested 3 months apart regularly. Serum HBV DNA levels were determined using the TaqMan and RealTime. YMDD (rt180M and rt204V) mutation was checked in patients who experienced virologic breakthrough (VBT). RESULTS: The correlation of HBV DNA observed between the RealTime and TaqMan was good for all 571 samples (R(2) = 0.797; P<0.001). However, the correlation in the 434 samples with HBV DNA level <3 log(10) IU/ml was not as good as in all samples (R(2) = 0.457). Overall, 21.5% of samples had a detection difference of ≥1 log(10) IU/ml with 91.9% of these having HBV DNA level <3 log(10) IU/ml. Twenty-four patients experiencedVBT. Three of these patients had acquired the YMDD mutation and exhibited discordant viral load results between the two methods tested. In each case, persistent HBV DNA was detected by RealTime and undetectable with TaqMan. Of the patients who experienced a VBT and had acquired YMDD mutation, 4.7% had undetectable HBV DNA by TaqMan while all were detectable with RealTime. CONCLUSIONS: RealTime assay is more sensitive and is little impacted by the development of drug resistant mutation.