Suzuki Yoshiyuki
Graduate School of Natural Sciences, Nagoya City University.
Genes Genet Syst. 2014;89(2):81-6. doi: 10.1266/ggs.89.81.
Group A rotavirus (RVA), an etiological agent of gastroenteritis in young mammals and birds, possesses a genome of 11 double-stranded RNA segments. Although it is believed that the RVA virion contains one copy of each genomic segment and that the positive-strand RNA (+RNA) is incorporated into the core shell, the packaging mechanisms of RVA are not well understood. Here, packaging signals of RVA were searched for by analyzing genomic sequences of mammalian and avian RVA, which are considered to have evolved independently without reassortment. Assuming that packaging is mediated by direct interaction between +RNA segments via base-pairing, co-evolving complementary nucleotide sites were identified within and between genomic segments. There were two pairs of co-evolving complementary sites within the segment encoding VP7 (the VP7 segment) and one pair between the NSP2 and NSP3 segments. In the VP7 segment, the co-evolving complementary sites appeared to form stem structures in both mammalian and avian RVA, supporting their functionality. In contrast, co-evolving complementary sites between the NSP2 and NSP3 segments tended to be free from base-pairings and constituted loop structures, at least in avian RVA, suggesting that they are involved in a specific interaction between these segments as a packaging signal.
A组轮状病毒（RVA）是幼龄哺乳动物和鸟类肠胃炎的病原体，其基因组由11个双链RNA片段组成。虽然人们认为RVA病毒粒子含有每个基因组片段的一个拷贝，并且正链RNA（+RNA）被整合到核心壳中，但RVA的包装机制尚未完全了解。在这里，通过分析哺乳动物和鸟类RVA的基因组序列来寻找RVA的包装信号，这些RVA被认为是独立进化且未发生重配的。假设包装是通过+RNA片段之间通过碱基配对的直接相互作用介导的，在基因组片段内部和之间鉴定出了共同进化的互补核苷酸位点。在编码VP7的片段（VP7片段）内有两对共同进化的互补位点，在NSP2和NSP3片段之间有一对。在VP7片段中，共同进化的互补位点在哺乳动物和鸟类RVA中似乎都形成了茎结构，支持了它们的功能。相比之下，NSP2和NSP3片段之间的共同进化互补位点倾向于不形成碱基配对，至少在鸟类RVA中构成环结构，这表明它们作为包装信号参与了这些片段之间的特定相互作用。
