Rapid quantification of hepatitis B virus DNA by real-time PCR using fluorescent hybridization probes

Abstract

A highly sensitive and rapid assay has been developed to quantify hepatitis B virus (HBV) DNA, based on the fluorescence resonance energy transfer principle and real-time PCR, using the LightCycler and a pair of specific fluorescent hybridization probes. This LightCycler real-time PCR assay (LC-PCR) detected HBV DNA in a linear range from 10 1 to 10 8 copies per reaction (250-2.5 × 10 9 copies ml -1), with a rapid PCR cycling time of 35 min. The assay was validated with two EUROHEP HBV DNA standards (ad and ay subtypes) and exhibited low intra-assay (< 6%) and inter-assay (< 16%) variation for both subtypes over the complete range of 7 orders of magnitude. The assay was evaluated clinically using serum samples from 120 HBsAg + individuals and 45 healthy controls who were negative for both HBsAg and anti-HBc. Levels of HBV DNA were measured in these samples using both the LC-PCR and Digene Hybrid Capture II HBV DNA (HCII) assays. The prevalence rates for HBV DNA in the HBsAg + serum samples were respectively 95% (114/120) and 56% (67/120) by LC-PCR and HCII (P < 0.01). All 67 HCII-positive samples tested positive with LC-PCR, while the 47 discordant samples showed low levels of HBV DNA (down to 265 copies ml -1), detectable only by the more sensitive LC-PCR assay. Levels of HBV DNA as measured by the two assays showed good correlation (r = 0.902; P < 0.001). The level of HBV DNA was significantly higher in HBeAg + than anti-HBe + samples (median 1.5 × 10 7 vs 4.6 × 10 4 copies ml -1; P < 0.01). It is concluded that this LC-PCR assay is clinically useful for the rapid, sensitive and accurate measurement of HBV DNA.