乙型肝炎病毒与cccDNA在血液中的清除动力学比较研究

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

目的以HBV为对照观察HBVcccDNA在外周血中的血液清除动力学特征，探讨在外周血中检测cccDNA的可行性。方法将12只1周龄上海麻鸭随机分为A、B两组，A组和B组每只鸭分别以1.2×10^9拷贝／ml的HBV携带者血清和含1．2×10^9拷贝／ml pBSHBV3．6Ⅱ质粒（模拟cccDNA）的人血清1ml颈静脉注射。在注射后0．25、2．4、6．8、12、24和32h，分别采静脉血进行HBVDNA定量检测。结果在注射后0．25～24h内血液中均可检测到HBV颗粒和质粒（cccDNA）。在注射后0．25～8h时间段内，血清HBV颗粒或pBSHBV3．6II质粒载量每2h下降1个数量级左右，8h后下降趋势明显减慢，32h后则未能检出。HBV和pBSHBV3．6Ⅱ质粒在鸭血液中载量的动态变化均符合单相指数衰减曲线模型，拟合曲线的相关指数在0．9593～0．9976之间。HBV和质粒（cccDNA）在鸭血液中的平均清除半衰期分别为3．5～5．4（4．5±0．8）h和3．9～6．1（4．5±0．8）h，二者差异无统计学意义（t=0．0523，P=0．9593）。结论①HBV cccDNA在血液中的清除动力学特征与HBV相似，血清HBV cccDNA检测在技术上具有可行性。②乙型肝炎病毒在血液中的清除半衰期远短于1．0～1．2d。

Objective To confirm whether analysis of its stability and clearance dynamics in it is feasible to detect HBV cccDNA based on an the blood of ducks. Methods 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 1.2×10^9 copies of HBV virion （group A） or plasmid pBS HBV 3.6 11 （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. Results 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 log10 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）. Conclusions 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.