[Comparative study on clearance dynamics of hepatitis B virion and cccDNA in blood]

To confirm whether it is feasible to detect HBV cccDNA based on an analysis of its stability and clearance dynamics in the blood of ducks.

Twelve 1-week-old ducklings were randomized into group A and group B, and each duckling was intravenously injected with 1 milliliter of serum containing 1.2 x 10(9) copies of HBV virion (group A) or plasmid pBS HBV 3.6 II (group B). At 0.25, 2, 4, 6, 8, 12, 24 and 32 h post-injection, serum HBV DNA level in each duckling was quantified by Real-time fluorescent PCR.

Both of HBV virion and plasmid pBS HBV 3.6 II could be detected from 0.25 h to 24 h after intravenous administration, and declined approximately by 1 log(10) every 2 hours within 8 h and was more slowly cleared at 8 h, and became undetectable at 32 h. Both of them are characteristic of one-phase exponential decay, as indicated by the relative index of the one-phase exponential curve ranging from 0.9593 to 0.9976. The mean half-life of HBV virion and plasmid (cccDNA) was 4.536 +/- 0.769 h (range: 3.5 - 5.4 h) and 4.5 +/- 0.8 h (range: 3.9 - 6.1 h) respectively. No significant difference was observed in the half-life between HBV virion and plasmid/cccDNA (t = 0.0523, P = 0.9593).

HBV cccDNA is similar to HBV virion in its characteristics of clearance dynamics in blood. Thus it is feasible to detect serum HBV cccDNA. The clearance half-life of Hepatitis B virus in serum is not as long as previously believed at 1.0 - 1.2 d.