疟疾仍是严重威胁人类健康的传染病之一，恶性疟原虫是其最致命的病原体。Var基因家族是其抗原变异和致病相关的关键毒力因子，约含60个成员，每个生活史只表达其中一个，即"相互排斥性"表达。现有观点认为，var基因的表达调控过程主要发生在转录水平：核周定位、染色质修饰、非编码序列等表观遗传学因素控制var基因启动子的转录状态。最近，我们通过基因敲除技术初步发现RNA外切酶体（Exosome）相关蛋白也参与var基因的转录沉默，提示var基因的表达还存在转录后水平的调控，即Exosome复合体介导的RNA降解途径，但是相关的机制尚不清楚。本课题拟利用多种转基因技术、免疫共沉淀、染色质免疫沉淀以及高通量的DNA/RNA深度测序等，对恶性疟原虫外切酶体(PfExosome)的组成和功能开展系统研究，为阐明恶性疟原虫var基因变异机制提供新的实验和理论依据，也将为恶性疟疾的防治提供新的思路和靶点。

Var multigene family is the major virulence factor associated with antigenic variation and pathogenesis of Plasmodium falciparum, the most lethal pathogen of malaria which is still being one of the public threats of human health. Only one out of the 60 members could be expressed in this gene family,which points to the "mutually exclusive expression" system. The regulation process of var gene expression is believed to occur at transcriptional level by epigenetic factors including perinuclear localization, chromatin modification, non-coding sequences, etc. Recently, preliminary experiments with gene knock out strategy revealed that the Exosome-associated protein was involved in the transcriptional silencing of var genes, indicated the existence of post-transcriptional regulation pathway of var expression. However, the related mechanism is still unclear. In this study, we aim to systematically analyze the composition of P.falciparum Exosome complex (PfExosome) and its regulatory functions of var expression by techniques as transgene,co-immuno-precipitation,chromatin immuno-precipitaion,high resolution sequencing, etc. The accomplishment of this project will dramatically contribute to elucidation of variation mechanism of var gene family, and also provide new ideas and targets of defence against severe malaria.