Modification of infection pattern of Duck hepatitis B virus by immuno regulatory durgs in both carrier and non-carrier ducks

为探讨鸭B肝炎病毒（DHBV）感染时间、感染方式与肝脏疾病的关系，进行了DHBV的实验传播。鸭乙型肝炎病毒（DHBV）在孵化后第1天和第3天接种，表现为持续感染，而在孵化后第5天和第5天后接种，则表现为一过性病毒血症。鸭肝炎病毒感染鸭孵化后3天和3天后看到肝炎活动，是非常弱的HBV相关的肝病相比。其次，研究了免疫调节药物对DHBV感染模式的改变。环磷酰胺免疫抑制治疗延长了病毒血症期，几乎没有肝脏炎症。类固醇治疗不能抑制肝炎，而且增加病毒复制和延长病毒血症期。OK-432免疫刺激治疗显示肝脏炎症增加，但不增加病毒复制。药物对DHBV感染模式的改变与HBV相似。宿主免疫反应似乎在确定感染模式和肝脏炎症活动方面具有相当大的作用。DHBV可作为研究HBV与宿主相互作用及病毒性肝炎免疫机制的一个有用模型。

To investigate the relationship among the time of viral infection, infection pattern and lever diseases experimental transmission of Duck hepatitis B virus (DHBV) was performed. Inoculation of DHBV into ducks on 1 day and 3 day posthatch revealed persistent infection, whereras inoculation into those on and after 5 day posthatch showed transient viremia. Hepatitis activity was seen in ducks inoculated with DHBV on and after 3 day posthatch and was very weak compared with HBV associated liver diseases. Second, alteration of infection pattern of DHBV by immuno regulatory drugs was investigated. Immunosuprresive treatment with cyclophosphamide extended viremic period and showed almost no hepatic inflammation. Treatment of steroid did not suppress the hepatitis and moreover increased viral replication and extended viremic period. Immuno stimmulation treatment with OK-432 showed increase in hepatic inflammation but did not increase viral replication. Alterations of infection pattern of DHBV with these drugs were quite similar to that of HBV. Host immune response seems to have a considerable role on determination of infection pattern and activity of hepatic inflammation. With these results DHBV can be a helpful model of HBV for studying host-viral interaction and immunological mechanism of viral hepatitis.