Analysis of packaging mechanism of influenza virus genome and the applications of viral vector

甲型流感病毒基因组由八个病毒RNA(VRNA)片段组成。虽然所有八个vRNA片段的产物都必须存在才能进行病毒复制，但人们对负责将这些片段整合到病毒中的机制(S)知之甚少。已经提出了两个模型来产生含有8个vRNA片段的感染性病毒粒子。随机掺入模型假定了所有vRNA的共同结构特征，使vRNA的任何组合都可以随机导入病毒粒子。选择性掺入模型预测每个vRNA片段中存在特定结构，导致一组八个vRNA片段掺入病毒粒子。我们证明了有效的病毒粒子形成必须存在八个不同的vRNA片段，并且神经氨酸酶vRNA编码区内的序列具有驱动该片段整合到病毒粒子中的信号。这些发现表明了单个vRNA片段的独特贡献，从而表明了vRNA重新募集到病毒粒子中的一种选择性机制。我们使用这些信号将外来基因整合到流感中。由于基因在感染细胞中得到了有效的表达，我们认为这是一种利用流感病毒作为表达载体的好方法。

The genome of influenza A virus is comprised of eight viral RNA (vRNA) segments. Although the products of all eight vRNA segments must be present for viral replication, little is known about the mechanism(s) responsible for incorporation of these segments into viricns. Two models have proposed for the generation of infectious virions containing eight vRNA segments. The random-incorporation model assumes a common structural feature in all the vRNAs, enabling any combination of vRNAs to be imported randomly into virions. The selective-incorporation model predicts the presence of specific structures in each vRNA segment, leading to the incorporation of a set of eight vRNA segments into virions. We demonstrate the eight different vRNA segments must be present for efficient virion formation and that sequences within the coding region of the neuraminidase vRNA possess a signal that drives incorporation of this segment into virions. These findings indicate a unique contribution from individual vRNA segments and thus suggest a selective mechanism of vRNA recruitment into virions. We used the signals to incorporate foreign genes into influenza. Because the genes are expressed effectively in the infected cells, we thought this is a good method to use influenza virus as an expressing vector.