Faaberg K S, Elam M R, Nelsen C J, Murtaugh M P
Department of Veterinary PathoBiology, University of Minnesota, St. Paul 55108, USA.
Adv Exp Med Biol. 1998;440:275-9. doi: 10.1007/978-1-4615-5331-1_36.
Porcine reproductive and respiratory syndrome virus (PRRSV), like all members of the order Nidoviridae, is expressed in the infected cell as a nested set of subgenomic (sg) RNAs with a common 5'-leader sequence. We have determined that the 5'-leader sequence for the US prototype strain (VR2332, Collins, et al., 1992) is distinct from the European prototype strain [Lelystad (LV); Wensvoort, et al., 1991, Meulenberg et al., 1993a], yet these two strains use almost the same sequence for downstream sites of 5'-leader-body junction formation. Analysis of VR2332 genomic sequence identified several potential 5'-leader-body junction sequences upstream of open reading frame (ORF) 7, coding for the nucleocapsid protein, that could be used for generation of VR2332 sgRNA7 transcripts. Sequence determinations of RT-PCR-generated cDNA clones of sgRNA7 identified two species of RNA7 transcripts in infected cells, one utilizing a leader-body junction sequence (AUAACC) 123 nucleotides upstream of the AUG start site and one utilizing a sequence (UAAACC) 9 nucleotides upstream of the AUG start site for ORF7 translation.
猪繁殖与呼吸综合征病毒（PRRSV）与尼多病毒目所有成员一样，在受感染细胞中表达为一组嵌套的亚基因组（sg）RNA，具有共同的5'-前导序列。我们已确定美国原型毒株（VR2332，Collins等人，1992年）的5'-前导序列与欧洲原型毒株[莱利斯塔德（LV）；Wensvoort等人，1991年，Meulenberg等人，1993a]不同，但这两种毒株在5'-前导序列与主体连接形成的下游位点使用几乎相同的序列。对VR2332基因组序列的分析在编码核衣壳蛋白的开放阅读框（ORF）7上游鉴定出几个潜在的5'-前导序列与主体连接序列，可用于生成VR2332 sgRNA7转录本。对sgRNA7的RT-PCR产生的cDNA克隆的序列测定在受感染细胞中鉴定出两种RNA7转录本，一种利用AUG起始位点上游123个核苷酸处的前导序列与主体连接序列（AUAACC），另一种利用ORF7翻译的AUG起始位点上游9个核苷酸处的序列（UAAACC）。
