Jridi Chiraz, Martin Jean-François, Marie-Jeanne Véronique, Labonne Gérard, Blanc Stéphane
UMR Biologie et Génétique des Interactions Plantes-Parasites, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, Montpellier, France.
J Virol. 2006 Mar;80(5):2349-57. doi: 10.1128/JVI.80.5.2349-2357.2006.
The complex structure of virus populations has been the object of intensive study in bacteria, animals, and plants for over a decade. While it is clear that tremendous genetic diversity is rapidly generated during viral replication, the distribution of this diversity within a single host remains an obscure area in this field of science. Among animal viruses, only Human immunodeficiency virus and Hepatitis C virus populations have recently been thoroughly investigated at an intrahost level, where they are structured as metapopulations, demonstrating that the host cannot be considered simply as a "bag" containing a homogeneous or unstructured swarm of mutant viral genomes. In plants, a few reports suggested a possible heterogeneous distribution of virus variants at different locations within the host but provided no clues as to how this heterogeneity is structured. Here, we report the most exhaustive study of the structure and evolution of a virus population ever reported at the intrahost level through the analysis of a Prunus tree infected by Plum pox virus for over 13 years following a single inoculation event and by using analysis of molecular variance at different hierarchical levels combined with nested clade analysis. We demonstrate that, following systemic invasion of the host, the virus population differentiates into several distinct populations that are isolated in different branches, where they evolve independently through contiguous range expansion while colonizing newly formed organs. Moreover, we present and discuss evidence that the tree harbors a huge "bank" of viral clones, each isolated in one of the myriad leaves.
十多年来，病毒群体的复杂结构一直是细菌、动物和植物领域深入研究的对象。虽然很明显，病毒复制过程中会迅速产生巨大的遗传多样性，但这种多样性在单个宿主内的分布在该科学领域仍是一个模糊不清的领域。在动物病毒中，只有人类免疫缺陷病毒和丙型肝炎病毒群体最近在宿主内水平上得到了彻底研究，它们在宿主内被构建为复合种群，这表明宿主不能简单地被视为一个包含突变病毒基因组的同质或无结构群体的“袋子”。在植物中，一些报告表明病毒变体在宿主内不同位置可能存在异质分布，但没有提供关于这种异质性是如何构建的线索。在这里，我们报告了有史以来在宿主内水平上对病毒群体结构和进化进行的最详尽研究，该研究通过分析一棵在单次接种事件后感染李痘病毒超过13年的李树，并结合不同层次水平的分子方差分析和嵌套分支分析。我们证明，在宿主被系统性侵染后，病毒群体分化为几个不同的群体，这些群体在不同的分支中隔离，在定殖新形成的器官时，它们通过连续的范围扩展独立进化。此外，我们展示并讨论了证据，即这棵树含有一个巨大的病毒克隆“库”，每个克隆都隔离在无数叶片中的一片上。
