Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
J Virol. 2013 Jan;87(2):882-9. doi: 10.1128/JVI.02363-12. Epub 2012 Oct 31.
The replication mechanism of bluetongue virus (BTV) has been studied by an in vivo reverse genetics (RG) system identifying the importance of certain BTV proteins for primary replication of the virus. However, a unique in vitro cell-free virus assembly system was subsequently developed, showing that it did not require the same set of viral components, which is indicative of differences in these two systems. Here, we studied the in vivo primary replicase complex more in-depth to determine the minimum components of the complex. We showed that while NS2 is an essential component of the primary replication stage during BTV infection, NS1 is not an essential component but may play a role in enhancing BTV protein synthesis. Furthermore, we demonstrated that VP7, a major structural protein of the inner core, is not required for primary replication but appears to stabilize the replicase complex. In contrast, VP3, the other major structural core protein, is an essential component of the complex, together with the three minor enzymatic proteins (VP1, VP4, and VP6) of the core. In addition, our data have demonstrated that the smallest minor protein, VP6, which is known to possess an RNA-dependent helicase activity, may also act as an RNA translocator during assembly of the primary replicase complex.
蓝舌病毒（BTV）的复制机制已通过体内反向遗传学（RG）系统进行了研究，该系统确定了某些 BTV 蛋白对病毒初次复制的重要性。然而，随后开发了一种独特的体外无细胞病毒组装系统，表明它不需要相同的一组病毒成分，这表明这两个系统存在差异。在这里，我们更深入地研究了体内初级复制酶复合物，以确定复合物的最小组成部分。我们表明，尽管 NS2 是 BTV 感染期间初级复制阶段的必需组成部分，但 NS1 不是必需组成部分，但可能在增强 BTV 蛋白合成中发挥作用。此外，我们证明，作为内部核心主要结构蛋白的 VP7 对于初级复制不是必需的，但似乎可以稳定复制酶复合物。相比之下，另一种主要的核心结构蛋白 VP3 是该复合物的必需组成部分，与核心的三个次要酶蛋白（VP1、VP4 和 VP6）一起。此外，我们的数据表明，最小的次要蛋白 VP6 已知具有 RNA 依赖性解旋酶活性，在初级复制酶复合物组装过程中也可能充当 RNA 转位酶。
