戊型肝炎病毒（HEV）的复制机制尚不清楚。病毒编码的microRNA可以通过调控宿主细胞靶基因和免疫系统而创造适宜病毒复制的环境。我们前期筛选到一条HEV编码的microRNA（miR-A6），过表达miR-A6可以显著增强HEV在体外细胞的复制；同时miR-A6在HEV感染的动物体内呈明显的组织特异性和时序性表达。通过荧光素酶活性实验发现，miR-A6对在天然免疫调节中发挥着重要作用的SIRP-α具有调控作用。据此推测miR-A6可能通过调控宿主的天然免疫系统从而介导HEV的复制过程。本项目拟利用云南优势流行HEV毒株通过实时定量PCR、流式细胞术、Western Blot和RNAi等技术进一步验证miR-A6促进HEV在A549和PLC/PRF/5细胞的复制，明确miR-A6促进HEV复制的作用；并探讨miR-A6通过调控SIRP-α逃逸宿主天然免疫的作用机制。

The mechanism of Hepatitis E virus (HEV) replication is still unclear. Viral encoded microRNAs may modulate both viral genes expression and host anti-viral defenses immunity system to benefit its replication. In our pervious study, a HEV encoded microRNA (miR-A6) was identified. Over-expression of miR-A6, HEV propagation was increased in vitro. The miR-A6 was expressed in special tissues during a productive viral infection in infected animals.In luciferase reporter assay, miR-A6 regulated the 3'UTR of SIRP-α, who play a critical role in innate immunity system against viral infection. Therefore, it is possible that miR-A6 regulate the innate immunity system to benefit the viral replication life cycles. In the present study, miR-A6 increase HEV replication in A549 and PLC/PRF/5 cells will be further identified by Real-Time qPCR, flow cytometry, western blot, and RNA interference (RNAi) by inoculated with HEV strain prevalent in Yunnan province. The role of miR-A6 in HEV replication, and how miR-A6 protect virus against innate immunity by regulation of SIRP-α will be found out.