Rümenapf T, Strauss E G, Strauss J H
Division of Biology, California Institute of Technology, Pasadena 91125.
J Virol. 1994 Jan;68(1):56-62. doi: 10.1128/JVI.68.1.56-62.1994.
Purified virions of Aura virus, a South American alphavirus related to Sindbis virus, were found to contain two RNA species, one of 12 kb and the other of 4.2 kb. Northern (RNA) blot analysis, primer extension analysis, and limited sequencing showed that the 12-kb RNA was the viral genomic RNA, whereas the 4.2-kb RNA present in virus preparations was identical to the 26S subgenomic RNA present in infected cells. The subgenomic RNA is the messenger for translation of the viral structural proteins, and its synthesis is absolutely required for replication of the virus. Although 26S RNA is present in the cytosol of all cells infected by alphaviruses, this is the first report of incorporation of the subgenomic RNA into alphavirus particles. Packaging of the Aura virus subgenomic mRNA occurred following infection of mosquito (Aedes albopictus C6/36), hamster (BHK-21), or monkey (Vero) cells. Quantitation of the amounts of genomic and subgenomic RNA both in virions and in infected cells showed that the ratio of genomic to subgenomic RNA was 3- to 10-fold higher in Aura virions than in infected cells. Thus, although the subgenomic RNA is packaged efficiently, the genomic RNA has a selective advantage during packaging. In contrast, in parallel experiments with Sindbis virus, packaging of subgenomic RNA was not detectable. We also found that subgenomic RNA was present in about threefold-greater amounts relative to genomic RNA in cells infected by Aura virus than in cells infected by Sindbis virus. Packaging of the Aura virus subgenomic RNA, but not those of other alphaviruses, suggests that Aura virus 26S RNA contains a packaging signal for incorporation into virions. The importance of the packaging of this RNA into virions in the natural history of the virus remains to be determined.
与辛德毕斯病毒相关的南美甲病毒——奥拉病毒的纯化病毒粒子被发现含有两种RNA分子，一种为12 kb，另一种为4.2 kb。Northern（RNA）印迹分析、引物延伸分析和有限测序表明，12 kb的RNA是病毒基因组RNA，而病毒制剂中存在的4.2 kb RNA与感染细胞中存在的26S亚基因组RNA相同。亚基因组RNA是病毒结构蛋白翻译的信使，其合成对于病毒复制是绝对必需的。尽管26S RNA存在于所有被甲病毒感染的细胞的胞质溶胶中，但这是亚基因组RNA掺入甲病毒粒子的首次报道。奥拉病毒亚基因组mRNA在蚊子（白纹伊蚊C6/36）、仓鼠（BHK - 21）或猴（Vero）细胞感染后发生包装。对病毒粒子和感染细胞中基因组RNA和亚基因组RNA含量的定量分析表明，奥拉病毒粒子中基因组RNA与亚基因组RNA的比例比感染细胞中的高3至10倍。因此，尽管亚基因组RNA被高效包装，但基因组RNA在包装过程中具有选择性优势。相比之下，在与辛德毕斯病毒的平行实验中，未检测到亚基因组RNA的包装。我们还发现，与被辛德毕斯病毒感染的细胞相比，被奥拉病毒感染的细胞中亚基因组RNA相对于基因组RNA的含量大约多三倍。奥拉病毒亚基因组RNA的包装，而非其他甲病毒的亚基因组RNA的包装，表明奥拉病毒26S RNA含有掺入病毒粒子的包装信号。这种RNA包装到病毒粒子中在病毒自然史中的重要性仍有待确定。
