PNAS:科学家发现新型真菌病毒！

rentianyixu

由Robert Coutts博士领导的研究人员发现了一种全新类型的真菌病毒。这项研究发表在《美国国家科学院院刊》(PNAS)上。

这种病毒感染烟曲霉菌型真菌，该细菌能引起人类患曲霉病。这种真菌靶向感染肺器官，并且是免疫力低下的个体发病率和死亡率的主要原因。

这种真菌病毒称为烟曲霉菌-1(AfuTmV-1)，是由四条双链核糖核酸(dsRNA)和具有独特序列特征的基因染色体组组成。与几乎所有病毒都不同的是它的遗传信息不是用壳体包裹而是包被在病毒编码的蛋白质中，这些核糖核蛋白结构通过原子力显微镜首次具体的显现出来。

最重要的是，在没有蛋白质衣壳的情况下，AfuTmV-1染色体组就其本身而言可以感染真菌，这个特性以前在dsRNA中从未有过，包括病毒在内。因此，染色体组可能因通过基因工程直接导入到真菌中而发生改变。

希望AfuTmV-1会被用于开发成一种沉默载体，它是一种可以切断真菌基因的工具，该载体可帮助研究分析烟曲霉菌中的什么物质会导致人类患曲霉病。

AfuTmV-1是新型真菌病毒家族的原型，但它并不是唯一的，因为相似的真菌病毒也被发现在不同的真菌属中，表明了在未来真菌界中用于构建通用沉默载体的这些dsRNA要素具有的潜在效用。

doi:10.1073/pnas.1419225112

A novel mycovirus from Aspergillus fumigatus contains four unique dsRNAs as its genome and is infectious as dsRNA

We report the discovery and characterization of a double-stranded RNA (dsRNA) mycovirus isolated from the human pathogenic fungus Aspergillus fumigatus, Aspergillus fumigatus tetramycovirus-1 (AfuTmV-1), which reveals several unique features not found previously in positive-strand RNA viruses, including the fact that it represents the first dsRNA (to our knowledge) that is not only infectious as a purified entity but also as a naked dsRNA. The AfuTmV-1 genome consists of four capped dsRNAs, the largest of which encodes an RNA-dependent RNA polymerase (RdRP) containing a unique GDNQ motif normally characteristic of negative-strand RNA viruses. The third largest dsRNA encodes an S-adenosyl methionine–dependent methyltransferase capping enzyme and the smallest dsRNA a P-A-S–rich protein that apparently coats but does not encapsidate the viral genome as visualized by atomic force microscopy. A combination of a capping enzyme with a picorna-like RdRP in the AfuTmV-1 genome is a striking case of chimerism and the first example (to our knowledge) of such a phenomenon. AfuTmV-1 appears to be intermediate between dsRNA and positive-strand ssRNA viruses, as well as between encapsidated and capsidless RNA viruses.