New gene expression vector using duck hepatitis B virus

利用鸭乙肝病毒（DHBV）动物模型研究了新的嗜肝基因表达载体。将含有野生型DHBV DNA的质粒DNA与脂质体络合，注入1日龄北京鸭外周静脉。DHBV DNA仅在肝细胞中表达，并检测到病毒复制。通过在前体细胞ORF中插入一个碱基，构建了前体细胞缺陷突变体。接种2周后血清中检测到DHBV突变体DNA的表达和复制，但接种16周后血清中的病毒滴度远低于野生型。对preore突变体感染肝脏的组织学分析显示，部分动物出现相当于慢性肝炎的炎症和轻微纤维化，提示可能与preore蛋白有关的发病机制有待进一步分析。构建了在前胚ORF中插入24个碱基的克隆，并将其接种于野鸭体内，得到了野生型病毒的复制。外源基因插入DHBV DNA的稳定性和能力有待分析。

New hepatotropic gene expression vector using the animal model of hepatitis B virus, duck hepatitis B virus (DHBV) was investigated. Plasmid DNA containing wild type of DHBV DNA was complexed with liposome, and injected into the peripheral vein of one-day-old Pekin duck. DHBV DNA was expressed exclusively in the hepatocytes and virus replication was detected. Precore defective mutant was constructed by one base insertion into precore ORF.The mutant DHBV DNA was also expressed and replicated virus was detected in the serum 2 weeks after inoculation, but virus titer in the serum was much less than wild type after 16 weeks. Histological analysis of precore mutant infected liver showed that some of the animals had the inflammation and slight fibrosis which equivalent to the chronic hepatitis, indicating that the pathogenesis related to the precore protein would be suggested and should be analyzed for the next step. The clone with 24 bases insertion in the precore ORF was constructed and inoculated into the ducks resulted the wild type virus replication. The stability and the capacity of foreign gene inserted into DHBV DNA needed to be analyzed.