miRNA在多种生物学过程中发挥重要的基因调控功能，最新发现MDV编码数十种miRNA，它们可能参与调控病毒的复制、潜伏感染、肿瘤发生等。MDV-1编码3个miRNA基因簇，其中Meq基因簇位于最重要的原癌基因Meq上游，它们在致病及致瘤中可能发挥关键作用。此前，我们已利用细菌人工染色体技术（BAC）和Rec E/T同源重组技术成功构建了这些miRNA单基因或基因簇的缺失毒株，经动物实验发现部分miRNA调控MDV-1的致病和致瘤表型。在此基础上，本项目拟重点开展Meq-clustered miRNA的宿主（鸡）靶基因的预测、筛选、鉴定，并对其调控的信号通路进行研究，以期为进一步阐明miRNA调控MDV-1致病及致瘤的分子机制奠定基础。MDV是目前唯一可用疫苗预防的致瘤性病毒，深入研究其编码的miRNA功能亦将为阐明miRNA调控肿瘤发生和发展的生物学、遗传学、免疫学等提供极好的动物模型。

MicroRNAs (miRNAs) are recently discovered small non-coding RNAs with important post-transcriptional regulatory roles in various cellular processes, including development, differentiation, and all aspects of cancer biology. Recently a large number of viral miRNAs have been reported to be encoded in the genomes of all three serotypes of Marek's disease virus (MDV) and several recent studies suggest that some of the MDV-1-encoded miRNAs have possible functions in the replication, latency, and oncogenesis of MDV. All of the MDV-1-encoded miRNAs are focused in three gene clusters, one of which is named as Meq-cluster for its location upstream of the oncogene Meq. Previously, we have constructed a serial of Meq-clustered miRNA-knocked out MDV strains using the bacterial artificial chromosomes (BAC) and Rec E/T homologous recombinant techniques and the animal experiments had showed that some of them are play important roles in regulating the phenotype of MDV pathogenesis and oncogenesis. For further revealing the biological regulatory roles of Meq-clustered miRNAs involved in the molecular pathogenesis and oncogenesis of MDV, we will focus on the prediction, screening, and characterization of their host (chicken) target mRNAs and related signal pathways. MDV-1 is one of the oncogenic herpesviruses and provided the first demonstration of the efficacy of anti-viral vaccination in the control of cancer in any species. As a consequence studies on MDV-encoded miRNAs provide an ideal model for investigating the possible regulatory roles of virus-encoded miRNAs in the biology, genetics, and immunology of tumorigenesis.