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标题：Expanded subgenomic mRNA transcriptome and coding capacity of a nidovirus
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作者：Han Di ; Joseph C. Madden ; Esther K. Morantz 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：42
页码：E8895-E8904
DOI：10.1073/pnas.1706696114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Members of the order Nidovirales express their structural protein ORFs from a nested set of 3′ subgenomic mRNAs (sg mRNAs), and for most of these ORFs, a single genomic transcription regulatory sequence (TRS) was identified. Nine TRSs were previously reported for the arterivirus Simian hemorrhagic fever virus (SHFV). In the present study, which was facilitated by next-generation sequencing, 96 SHFV body TRSs were identified that were functional in both infected MA104 cells and macaque macrophages. The abundance of sg mRNAs produced from individual TRSs was consistent over time in the two different cell types. Most of the TRSs are located in the genomic 3′ region, but some are in the 5′ ORF1a/1b region and provide alternative sources of nonstructural proteins. Multiple functional TRSs were identified for the majority of the SHFV 3′ ORFs, and four previously identified TRSs were found not to be the predominant ones used. A third of the TRSs generated sg mRNAs with variant leader–body junction sequences. Sg mRNAs encoding E′, GP2, or ORF5a as their 5′ ORF as well as sg mRNAs encoding six previously unreported alternative frame ORFs or 14 previously unreported C-terminal ORFs of known proteins were also identified. Mutation of the start codon of two C-terminal ORFs in an infectious clone reduced virus yield. Mass spectrometry detected one previously unreported protein and suggested translation of some of the C-terminal ORFs. The results reveal the complexity of the transcriptional regulatory mechanism and expanded coding capacity for SHFV, which may also be characteristic of other nidoviruses.
关键词：nidovirus ; Simian hemorrhagic fever virus ; transcription regulatory sequences ; subgenomic mRNAs ; next-generation sequencing