Under the Baltimore nucleic acid-based virus classification scheme, the herpesvirus human cytomegalovirus (HCMV) is a Class I virus, meaning that it contains a double-stranded DNA genome—and no RNA. Here, we report sub-particle cryoEM reconstructions of HCMV virions at 2.9 Å resolution revealing structures resembling non-coding transfer RNAs (tRNAs) associated with the virion’s capsid-bound tegument protein, pp150. Through deep sequencing, we show that these RNA sequences match human tRNAs, and we built atomic models using the most abundant tRNA species. Based on our models, tRNA recruitment is mediated by the electrostatic interactions between tRNA phosphate groups and the helix-loop-helix motif of HCMV pp150. The specificity of these interactions may explain the absence of such tRNA densities in murine cytomegalovirus and other human herpesviruses.

根据巴尔的摩基于核酸的病毒分类方案，人类巨细胞病毒 (HCMV) 疱疹病毒属于 I 类病毒，这意味着它包含双链 DNA 基因组，但不含 RNA。在这里，我们以 2.9 Å 分辨率报告了 HCMV 病毒粒子的亚粒子冷冻电镜重建，揭示了类似于与病毒粒子衣壳结合的皮层蛋白 pp150 相关的非编码转移 RNA (tRNA) 的结构。通过深度测序，我们证明这些 RNA 序列与人类 tRNA 相匹配，并且我们使用最丰富的 tRNA 物种构建了原子模型。根据我们的模型，tRNA 募集是由 tRNA 磷酸基团与 HCMV pp150 的螺旋-环-螺旋基序之间的静电相互作用介导的。