Smertina Elena, Hall Robyn N, Urakova Nadya, Strive Tanja, Frese Michael
Commonwealth Scientific and Industrial Research Organization, Health and Biosecurity, Canberra, ACT, Australia.
Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia.
Front Microbiol. 2021 Jul 14;12:712710. doi: 10.3389/fmicb.2021.712710. eCollection 2021.
The are a family of viruses with a single-stranded, non-segmented RNA genome of positive polarity. The ongoing discovery of caliciviruses has increased the number of genera in this family to 11 (, , , , , , , , , , and ). Caliciviruses infect a wide range of hosts that include fishes, amphibians, reptiles, birds, and marine and land mammals. All caliciviruses have a genome that encodes a major and a minor capsid protein, a genome-linked viral protein, and several non-structural proteins. Of these non-structural proteins, only the helicase, protease, and RNA-dependent RNA polymerase share clear sequence and structural similarities with proteins from other virus families. In addition, all caliciviruses express two or three non-structural proteins for which functions have not been clearly defined. The sequence diversity of these non-structural proteins and a multitude of processing strategies suggest that at least some have evolved independently, possibly to counteract innate and adaptive immune responses in a host-specific manner. Studying these proteins is often difficult as many caliciviruses cannot be grown in cell culture. Nevertheless, the study of recombinant proteins has revealed many of their properties, such as intracellular localization, capacity to oligomerize, and ability to interact with viral and/or cellular proteins; the release of non-structural proteins from transfected cells has also been investigated. Here, we will summarize these findings and discuss recent studies that identified previously overlooked putative functional domains and structural features, including transmembrane domains that suggest the presence of viroporins.
杯状病毒是一类具有正链单链、非分段RNA基因组的病毒家族。杯状病毒的不断发现使该家族的属数量增加到11个（诺如病毒属、札幌病毒属、兔出血症病毒属、猫杯状病毒属、海豹瘟病毒属、诺卡病毒属、扎如病毒属、魁北克病毒属、科克病毒属、萨科病毒属和瓦伦丁病毒属）。杯状病毒感染广泛的宿主，包括鱼类、两栖动物、爬行动物、鸟类以及海洋和陆地哺乳动物。所有杯状病毒都有一个基因组，该基因组编码一种主要衣壳蛋白和一种次要衣壳蛋白、一种与基因组相连的病毒蛋白以及几种非结构蛋白。在这些非结构蛋白中，只有解旋酶、蛋白酶和RNA依赖性RNA聚合酶与其他病毒家族的蛋白具有明显的序列和结构相似性。此外，所有杯状病毒都表达两种或三种功能尚未明确的非结构蛋白。这些非结构蛋白的序列多样性和多种加工策略表明，至少其中一些是独立进化的，可能是以宿主特异性方式对抗先天性和适应性免疫反应。由于许多杯状病毒无法在细胞培养中生长，研究这些蛋白往往很困难。然而，对重组蛋白的研究揭示了它们的许多特性，如细胞内定位、寡聚化能力以及与病毒和/或细胞蛋白相互作用的能力；也对转染细胞中非结构蛋白的释放进行了研究。在这里，我们将总结这些发现，并讨论最近的研究，这些研究确定了以前被忽视的假定功能域和结构特征，包括提示存在病毒孔蛋白的跨膜结构域。
