Department of Infectious Diseases, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China.
Virol J. 2013 Jun 28;10:214. doi: 10.1186/1743-422X-10-214.
It has been suggested that different hepatitis B virus (HBV) genotypes may have distinct virological characteristics that correlate with clinical outcomes during antiviral therapy and the natural course of infection. Hydrodynamic injection (HI) of HBV in the mouse model is a useful tool for study of HBV replication in vivo. However, only HBV genotype A has been used for studies with HI.
We constructed 3 replication-competent clones containing 1.1, 1.2 and 1.3 fold overlength of a HBV genotype B genome and tested them both in vitro and in vivo. Moreover, A HBV genotype B clone based on the pAAV-MCS vector was constructed with the 1.3 fold HBV genome, resulting in the plasmid pAAV-HBV1.3B and tested by HI in C57BL/6 mice. Application of siRNA against HBx gene was tested in HBV genotype B HI mouse model.
The 1.3 fold HBV clone showed higher replication and gene expression than the 1.1 and 1.2 fold HBV clones. Compared with pAAV-HBV1.2 (genotype A), the mice HI with pAAV-HBV1.3B showed higher HBsAg and HBeAg expression as well as HBV DNA replication level but a higher clearance rate. Application of two plasmids pSB-HBxi285 and pSR-HBxi285 expressing a small/short interfering RNA (siRNA) to the HBx gene in HBV genotype B HI mouse model, leading to an inhibition of HBV gene expression and replication. However, HBV gene expression may resume in some mice despite an initial delay, suggesting that transient suppression of HBV replication by siRNA may be insufficient to prevent viral spread, particularly if the gene silencing is not highly effective.
Taken together, the HI mouse model with a HBV genotype B genome was successfully established and showed different characteristics in vivo compared with the genotype A genome. The effectiveness of gene silencing against HBx gene determines whether HBV replication may be sustainably inhibited by siRNA in vivo.
有人认为，不同的乙型肝炎病毒（HBV）基因型可能具有不同的病毒学特征，这些特征与抗病毒治疗期间和感染自然过程中的临床结果相关。在小鼠模型中，HBV 的水力注射（HI）是研究体内 HBV 复制的有用工具。然而，仅使用 HBV 基因型 A 进行了 HI 研究。
我们构建了 3 个含有 1.1、1.2 和 1.3 倍 HBV 基因型 B 基因组全长的复制型克隆，并在体外和体内进行了测试。此外，我们基于 pAAV-MCS 载体构建了一个含有 1.3 倍 HBV 基因组的 A 基因型 B 克隆，导致质粒 pAAV-HBV1.3B，并通过 C57BL/6 小鼠的 HI 进行了测试。我们还在 HBV 基因型 B HI 小鼠模型中测试了针对 HBx 基因的 siRNA 的应用。
1.3 倍 HBV 克隆的复制和基因表达水平均高于 1.1 和 1.2 倍 HBV 克隆。与 pAAV-HBV1.2（基因型 A）相比，用 pAAV-HBV1.3B 进行 HI 的小鼠显示出更高的 HBsAg 和 HBeAg 表达以及 HBV DNA 复制水平，但清除率更高。应用两个表达小/短干扰 RNA（siRNA）的质粒 pSB-HBxi285 和 pSR-HBxi285 到 HBV 基因型 B HI 小鼠模型中的 HBx 基因，导致 HBV 基因表达和复制受到抑制。然而，尽管最初有延迟，但一些小鼠中的 HBV 基因表达可能会恢复，这表明 siRNA 对 HBV 复制的短暂抑制可能不足以阻止病毒传播，特别是如果基因沉默效果不高。
总之，成功建立了携带 HBV 基因型 B 基因组的 HI 小鼠模型，与基因型 A 基因组相比，在体内显示出不同的特征。针对 HBx 基因的基因沉默的有效性决定了 siRNA 是否可以在体内持续抑制 HBV 复制。
