DALI server data (zip file).

It has been 49 years since the last discovery of a new virus family in the model yeast Saccharomyces cerevisiae. A large-scale screen to determine the diversity of double-stranded RNA (dsRNA) viruses in S. cerevisiae has identified multiple novel viruses from the family Partitiviridae that have been previously shown to infect plants, fungi, protozoans, and insects. Most S. cerevisiae partitiviruses (ScPVs) are associated with strains of yeasts isolated from coffee and cacao beans. The presence of partitiviruses was confirmed by sequencing the viral dsRNAs and purifying and visualizing isometric, non-enveloped viral particles. ScPVs have a typical bipartite genome encoding an RNA-dependent RNA polymerase (RdRP) and a coat protein (CP). Phylogenetic analysis of ScPVs identified three species of ScPV, which are most closely related to viruses of the genus Cryspovirus from the mammalian pathogenic protozoan Cryptosporidium parvum. Molecular modeling of the ScPV RdRP revealed a conserved tertiary structure and catalytic site organization when compared to the RdRPs of the Picornaviridae. The ScPV CP is the smallest so far identified in the Partitiviridae and has structural homology with the CP of other partitiviruses but likely lacks a protrusion domain that is a conspicuous feature of other partitivirus particles. ScPVs were stably maintained during laboratory growth and were successfully transferred to haploid progeny after sporulation, which provides future opportunities to study partitivirus-host interactions using the powerful genetic tools available for the model organism S. cerevisiae.距上一次在模式酿酒酵母（Saccharomyces cerevisiae）中发现全新病毒科已有49年之久。针对该酿酒酵母体内双链RNA（double-stranded RNA, dsRNA）病毒多样性开展的大规模筛选，从分体病毒科（Partitiviridae）中鉴定出多种新型病毒——此前研究已证实该病毒科可侵染植物、真菌、原生动物与昆虫。绝大多数酿酒酵母分体病毒（S. cerevisiae partitiviruses, ScPVs）均与分离自咖啡与可可豆的酵母菌株相关联。研究人员通过对病毒dsRNA进行测序，并纯化并可视化等轴无包膜病毒颗粒的方式，证实了分体病毒的存在。ScPVs拥有典型的二分体基因组，可编码RNA依赖的RNA聚合酶（RNA-dependent RNA polymerase, RdRP）与衣壳蛋白（coat protein, CP）。对ScPVs的系统发育分析鉴定出3种酿酒酵母分体病毒，它们与源自哺乳动物致病性原生动物微小隐孢子虫（Cryptosporidium parvum）的隐孢子病毒属（Cryspovirus）病毒亲缘关系最近。对ScPV RdRP的分子建模结果显示，与小RNA病毒科（Picornaviridae）的RdRP相比，其三级结构与催化位点排布均具有保守性。ScPV CP是目前分体病毒科中已鉴定出的最小衣壳蛋白，虽与其他分体病毒的CP具有结构同源性，但大概率缺失其他分体病毒颗粒中显著存在的突出结构域。ScPVs在实验室培养过程中可稳定维持，并可在孢子形成后成功传递至单倍体子代中，这为借助模式生物酿酒酵母所具备的强大遗传工具研究分体病毒-宿主互作提供了未来的研究契机。