Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche, 70126 Bari, Italy.
Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Naples, Italy.
Mol Plant Pathol. 2018 May;19(5):1075-1089. doi: 10.1111/mpp.12587. Epub 2017 Oct 4.
A novel negative-stranded (ns) RNA virus associated with a severe citrus disease reported more than 80 years ago has been identified. Transmission electron microscopy showed that this novel virus, tentatively named citrus concave gum-associated virus, is flexuous and non-enveloped. Notwithstanding, its two genomic RNAs share structural features with members of the genus Phlebovirus, which are enveloped arthropod-transmitted viruses infecting mammals, and with a group of still unclassified phlebo-like viruses mainly infecting arthropods. CCGaV genomic RNAs code for an RNA-dependent RNA polymerase, a nucleocapsid protein and a putative movement protein showing structural and phylogenetic relationships with phlebo-like viruses, phleboviruses and the unrelated ophioviruses, respectively, thus providing intriguing evidence of a modular genome evolution. Phylogenetic reconstructions identified an invertebrate-restricted virus as the most likely ancestor of this virus, revealing that its adaptation to plants was independent from and possibly predated that of the other nsRNA plant viruses. These data are consistent with an evolutionary scenario in which trans-kingdom adaptation occurred several times during the history of nsRNA viruses and followed different evolutionary pathways, in which genomic RNA segments were gained or lost. The need to create a new genus for this bipartite nsRNA virus and the impact of the rapid and specific detection methods developed here on citrus sanitation and certification are also discussed.
一种与 80 多年前报道的严重柑橘病害相关的新型负链（ns）RNA 病毒已经被鉴定。透射电子显微镜显示，这种新型病毒，暂定名为柑橘凹叶病伴随病毒，是弯曲的，无包膜的。然而，它的两个基因组 RNA 与属 Phlebovirus 的成员共享结构特征，后者是包膜节肢动物传播的病毒，感染哺乳动物，以及一组尚未分类的类似 Phlebovirus 的病毒，主要感染节肢动物。CCGaV 基因组 RNA 编码 RNA 依赖性 RNA 聚合酶、核衣壳蛋白和一个假定的运动蛋白，它们与类似 Phlebovirus 的病毒、Phlebovirus 和不相关的 Ophiovirus 具有结构和系统发育关系，因此提供了模块化基因组进化的有趣证据。系统发育重建确定了一种无脊椎动物限制的病毒是该病毒最有可能的祖先，这表明它对植物的适应是独立于其他 nsRNA 植物病毒的，并且可能早于其他 nsRNA 植物病毒。这些数据与一个进化情景一致，即在 nsRNA 病毒的历史上，跨界适应发生了多次，并遵循了不同的进化途径，其中基因组 RNA 片段的获得或丢失。需要为这种双组分 nsRNA 病毒创建一个新属，以及这里开发的快速和特异的检测方法对柑橘卫生和认证的影响也进行了讨论。
