Kuo L, Chen Z, Rowland R R, Faaberg K S, Plagemann P G
Department of Microbiology, University of Minnesota, Minneapolis 55455.
Virus Res. 1992 Apr;23(1-2):55-72. doi: 10.1016/0168-1702(92)90067-j.
The 3'-terminal 1314 nucleotides of the genome of one isolate of lactate dehydrogenase-elevating virus, LDV-P, has been derived by sequence analyses of cDNAs from several genomic libraries and compared to that of another LDV isolate, LDV-C (Godeny et al. (1990) Virol. 177, 768-771). The 3'-non-coding segment of 80 nucleotides of the two LDV genomes is identical, whereas marked, but varying nucleotide and amino acid divergence is apparent in the three upstream overlapping open reading frames (ORF). The third ORF from the 3'-end exhibits only 82% nucleotide and 90% amino acid identity, whereas the 3'-terminal ORF, which encodes the nucleocapsid protein, exhibits approximately 99% amino acid identity. The second 3'-terminal ORF encodes an 18.8 kDa protein which lacks N-glycosylation sites but possesses 2 or 3 potential transmembrane helices in the N-terminal half of the molecule. A similar membrane organization is observed for the corresponding protein of equine arteritis virus and the M protein of mouse hepatitis virus. The sequence analyses combined with Northern hybridization analyses of RNA from LDV-infected macrophages and spleens of LDV-infected mice indicate that the three ORFs encoded by the 3'-terminal end of the LDV genome are expressed via the three smallest mRNAs (mRNAs 6-8) of the seven subgenomic mRNAs of LDV (mRNAs 2-8), which range in size from about 0.8 to 3.6 kb. All mRNAs have been shown to carry poly(A)-tracts and a common leader sequence. The seven mRNAs were produced in infected macrophage cultures concomitantly with genomic LDV RNA. Maximum LDV RNA synthesis was observed between 6 and 8 h post-infection. The same seven subgenomic mRNAs were detected in macrophages infected with three different isolates of LDV, but different relative amounts of some of the mRNAs were produced. The relative proportions of molecules of mRNAs 1-8 present in 6 h LDV-P-infected macrophages were about 13, 5, 5, 8, 6, 11, 11 and 27% of the total, respectively.
通过对来自几个基因组文库的cDNA进行序列分析，获得了乳酸脱氢酶升高病毒（LDV）的一个分离株LDV-P基因组3'末端的1314个核苷酸，并将其与另一个LDV分离株LDV-C的相应序列进行了比较（Godeny等人，（1990年），《病毒学》，第177卷，第768 - 771页）。两个LDV基因组80个核苷酸的3'非编码区是相同的，然而，在三个上游重叠开放阅读框（ORF）中，明显存在显著但不同的核苷酸和氨基酸差异。从3'末端起的第三个ORF仅表现出82%的核苷酸同一性和90%的氨基酸同一性，而编码核衣壳蛋白的3'末端ORF表现出约99%的氨基酸同一性。第二个3'末端ORF编码一种18.8 kDa的蛋白质，该蛋白质缺乏N - 糖基化位点，但在分子的N端一半区域具有2个或3个潜在的跨膜螺旋。在马动脉炎病毒的相应蛋白和小鼠肝炎病毒的M蛋白中观察到类似的膜结构。序列分析与对LDV感染的巨噬细胞和LDV感染小鼠脾脏中的RNA进行的Northern杂交分析相结合，表明LDV基因组3'末端编码的三个ORF通过LDV七个亚基因组mRNA（mRNA 2 - 8）中最小的三个mRNA（mRNA 6 - 8）进行表达，这些mRNA的大小范围约为0.8至3.6 kb。所有mRNA均已显示携带多聚（A）尾和一个共同的前导序列。在感染的巨噬细胞培养物中，这七个mRNA与基因组LDV RNA同时产生。在感染后6至8小时观察到最大的LDV RNA合成。在感染三种不同LDV分离株的巨噬细胞中检测到相同的七个亚基因组mRNA，但产生的一些mRNA的相对量不同。在感染LDV - P 6小时的巨噬细胞中，mRNA Ⅰ - Ⅷ的分子相对比例分别约占总量的13%、5%、5%、8%、6%、1l%、11%和27%。
