Understanding the Pseudodiploidy of the Retroviral Genome

逆转录病毒科在病毒科中是独特的，因为一个病毒粒子包装了其基因组的两个全长拷贝。然而，每次感染事件只产生一种原病毒；因此，逆转录病毒是假二倍体。我们不完全了解假二倍体的好处，我们建议检查在一个病毒粒子中包装两个rna的好处。此外，逆转录病毒用来包装两种rna的确切机制目前还不清楚。我们进行了实验，研究了共包装RNA伴侣选择的机制，并证明了DIS序列在这一过程中起着重要作用。在我们的实验系统中，我们可以通过操纵两种病毒的DIS序列来增加或减少杂合病毒的形成。这些结果表明Gag识别和包装一个RNA二聚体而不是两个单体。我们将继续剖析对RNA二聚体包装重要的元件，包括顺式作用元件，如DIS和反式作用元件，如Gag蛋白。使用细胞融合实验，我们将阐明何时何地选择共包装RNA伴侣发生。这些研究将揭示逆转录病毒复制的最基本特征之一，并将说明假二倍体的优点和局限性。[对应于2007年4月HIV耐药项目实地考察报告中的胡项目2]

Retroviridae are unique among virus families in that one virion packages two full-length copies of its genome. However, each infectious event generates only one provirus; thus, retroviruses are pseudodiploid. We do not fully understand the benefit of pseudodiploidy, and we propose to examine the benefit of packaging two RNAs in one virion. Additionally, the exact mechanisms that retroviruses use to package two RNAs are not currently understood. We have performed experiments examining the mechanisms of copackaged RNA partner selection and have demonstrated that the DIS sequence plays an important role in this process. In our experimental system, we can increase or decrease heterozygous virus formation by manipulating the DIS sequences of the two viruses. These results suggest that Gag recognizes and packages an RNA dimer rather than two monomers. We will continue to dissect elements important to packaging the RNA dimer, including cis-acting elements such as DIS and trans-acting elements such as Gag proteins. Using a cell-fusion assay, we will elucidate when and where selection of copackaged RNA partners occur. These studies will shed light on one of the most fundamental features of retroviral replication and will illustrate both the advantages and the limitations of pseudodiploidy. [Corresponds to Hu Project 2 in the April 2007 site visit report of the HIV Drug Resistance Program]