Hepatitis B virus DNA quantification with the three-in-one (3io) method allows accurate single-step differentiation of total HBV DNA and cccDNA in biopsy-size liver samples

Abstract

Background: Hepatitis B virus (HBV) replicates via reverse transcription converting its partially double stranded genome into the covalently closed circular DNA (cccDNA). The long-lasting cccDNA serves as a replication intermediate in the nuclei of hepatocytes. It is an excellent, though evasive, parameter for monitoring the course of liver disease and treatment efficiency.

Objective: To develop and test a new approach for HBV DNA quantification in serum and small-size liver samples.

Study design: The p3io plasmid contains an HBV fragment and human β-actin gene (hACTB) as a standard. Respective TaqMan probes were labeled with different fluorescent dyes. A triplex real-time PCR for simultaneous quantification of total HBV DNA, cccDNA and hACTB could be established.

Results: Three-in-one method allows simultaneous analysis of 3 targets with a lower limit of quantification of 48 copies per 20 μl PCR reaction and a wide range of linearity (R(2)>0.99, p<0.0001) for all measured sequences. The method showed a pan-genotypic specificity among genotypes A-F with serum DNA samples from HBV infected patients. Total HBV DNA and cccDNA could be quantified in 32 and 22 of 33 FFPE preserved liver specimens, respectively. Total HBV DNA concentrations quantified by the 3io method remained comparable with Cobas TaqMan HBV Test v2.0.

Conclusions: The three-in-one protocol allows the single step quantification of viral DNA in samples from different sources. Therefore lower sample input, faster data acquisition, a lowered error and significantly lower costs are the advantages of the method.

Keywords: FFPE; HBV DNA; HBsAg; Quantification; Real-time PCR; cccDNA.