Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
J Gen Virol. 2010 Feb;91(Pt 2):313-28. doi: 10.1099/vir.0.017608-0. Epub 2009 Dec 2.
The negative-sense RNA genome of influenza A virus is composed of eight segments, which encode 12 proteins between them. At the final stage of viral assembly, these genomic virion (v)RNAs are incorporated into the virion as it buds from the apical plasma membrane of the cell. Genome segmentation confers evolutionary advantages on the virus, but also poses a problem during virion assembly as at least one copy of each of the eight segments is required to produce a fully infectious virus particle. Historically, arguments have been presented in favour of a specific packaging mechanism that ensures incorporation of a full genome complement, as well as for an alternative model in which segments are chosen at random but packaged in sufficient numbers to ensure that a reasonable proportion of virions are viable. The question has seen a resurgence of interest in recent years leading to a consensus that the vast majority of virions contain no more than eight segments and that a specific mechanism does indeed function to select one copy of each vRNA. This review summarizes work leading to this conclusion. In addition, we describe recent progress in identifying the specific packaging signals and discuss likely mechanisms by which these RNA elements might operate.
流感 A 病毒的负义 RNA 基因组由八个片段组成，它们在它们之间编码 12 种蛋白质。在病毒装配的最后阶段，这些基因组病毒（v）RNA 作为病毒从细胞的顶端质膜出芽时被整合到病毒中。基因组分段赋予病毒进化优势，但在病毒装配过程中也带来了问题，因为至少需要每个片段的一个副本才能产生完全有感染力的病毒颗粒。从历史上看，有人提出了有利于特定包装机制的论点，该机制确保了完整基因组的互补，以及另一种模型，其中片段随机选择，但包装数量足以确保相当比例的病毒颗粒具有活力。近年来，这个问题重新引起了人们的兴趣，导致大多数人达成共识，即绝大多数病毒颗粒中不超过八个片段，并且确实存在一种特定的机制来选择每个 vRNA 的一个副本。这篇综述总结了得出这一结论的工作。此外，我们描述了最近在鉴定特定包装信号方面的进展，并讨论了这些 RNA 元件可能发挥作用的可能机制。
