Petersen J, Dandri M, Gupta S, Rogler C E
Marion Bessin Liver Research Center, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Proc Natl Acad Sci U S A. 1998 Jan 6;95(1):310-5. doi: 10.1073/pnas.95.1.310.
To investigate host and viral mechanisms determining hepadnaviral persistence and hepatocarcinogenesis, we developed a mouse model by transplanting woodchuck hepatocytes into the liver of mice that contain the urokinase-type plasminogen activator transgene (uPA) and lack mature B and T lymphocytes due to a recombination activation gene 2 (RAG-2) gene knockout. The woodchuck hepatocytes were transplanted via intrasplenic injection and were found to integrate into the recipient mouse liver cord structure. Normal adult woodchuck hepatocytes proliferated and reconstituted up to 90% of the uPA/RAG-2 mouse liver. uPA/RAG-2 mice containing woodchuck hepatocytes were infectable with woodchuck hepatitis virus (WHV) and showed WHV replication for at least 10 months with titers up to 1 x 10(11) virions per ml in the peripheral blood. WHV-infected hepatocytes from chronic carrier woodchucks also established a persistent infection in uPA/RAG-2 mice after an 8- to 12-week lag period of viremia. Although WHV envelope, core, and X proteins were produced in the uPA/RAG-2 mice, no inflammatory host immune response was observed in the liver of WHV-replicating mice. A first antiviral test demonstrated a greater than four orders of magnitude drop in WHV titer in response to interferon alpha treatment. WHV replication was up-regulated by dexamethasone treatment. Comparison of precancerous lesions in donor woodchucks versus recipient uPA/RAG-2 mice revealed an enrichment of dysplastic precancerous hepatocytes in transplanted mice. Clonal amplification of hepatocytes from a woodchuck with hepatocellular carcinomas was demonstrated by the detection of unique WHV DNA integration patterns in hepatocellular carcinomas that arose in uPA/RAG-2 mice. In the absence of B or T cell-mediated immune responses, WHV establishes a persistent noncytotoxic infection of woodchuck hepatocytes in uPA/RAG-2 chimeric mouse livers. Further studies of the kinetics of hepadnavirus infection and replication in quiescent and proliferating hepatocytes should increase our understanding of hepadnavirus spread and aid in the design of therapies to block or cure persistent infection.
为了研究决定嗜肝DNA病毒持续存在和肝癌发生的宿主及病毒机制，我们通过将土拨鼠肝细胞移植到含有尿激酶型纤溶酶原激活剂转基因（uPA）且由于重组激活基因2（RAG-2）基因敲除而缺乏成熟B和T淋巴细胞的小鼠肝脏中，建立了一种小鼠模型。土拨鼠肝细胞通过脾内注射进行移植，并被发现整合到受体小鼠肝索结构中。正常成年土拨鼠肝细胞增殖并重建了高达90%的uPA/RAG-2小鼠肝脏。含有土拨鼠肝细胞的uPA/RAG-2小鼠可感染土拨鼠肝炎病毒（WHV），并显示WHV复制至少10个月，外周血中病毒滴度高达每毫升1×10¹¹个病毒粒子。来自慢性携带土拨鼠的WHV感染肝细胞在病毒血症8至12周的滞后期后，也在uPA/RAG-2小鼠中建立了持续感染。尽管在uPA/RAG-2小鼠中产生了WHV包膜、核心和X蛋白，但在WHV复制小鼠的肝脏中未观察到炎症性宿主免疫反应。首次抗病毒试验表明，干扰素α治疗后WHV滴度下降超过四个数量级。地塞米松治疗上调了WHV复制。比较供体土拨鼠与受体uPA/RAG-2小鼠的癌前病变发现，移植小鼠中发育异常的癌前肝细胞有所富集。通过检测uPA/RAG-2小鼠中发生的肝细胞癌中独特的WHV DNA整合模式，证实了来自患有肝细胞癌的土拨鼠的肝细胞的克隆扩增。在没有B或T细胞介导的免疫反应的情况下，WHV在uPA/RAG-2嵌合小鼠肝脏中建立了土拨鼠肝细胞的持续非细胞毒性感染。对嗜肝DNA病毒在静止和增殖肝细胞中感染和复制动力学的进一步研究，应会增加我们对嗜肝DNA病毒传播的理解，并有助于设计阻断或治愈持续感染的疗法。
