Conzelmann K K, Visser N, Van Woensel P, Thiel H J
Federal Research Centre for Virus Diseases of Animals, Tübingen, Federal Republic of Germany.
Virology. 1993 Mar;193(1):329-39. doi: 10.1006/viro.1993.1129.
Porcine reproductive and respiratory syndrome virus (PRRSV)-specific cDNA clones spanning the 3' terminal 5 kb of the genomic RNA were isolated, sequenced, and used as probes for identification of PRRSV-specific RNAs. The PRRSV genome is a positive-stranded polyadenylated RNA of about 15 kb. In infected cells, a 3' coterminal nested set of six major subgenomic mRNAs could be demonstrated. Within the 3' terminal 3.5 kb of the PRRSV genome, six overlapping reading frames (ORFs) were identified, each most likely expressed by one of the subgenomic mRNAs. Amino acid sequence comparisons revealed that the most 3' terminal ORF (ORF7) encodes the PRRSV nucleocapsid protein with a calculated molecular weight of 14 kDa. It displays 44.8% amino acid identity with the capsid protein of lactate dehydrogenase-elevating virus (LDV) and 23.6% with that of equine arteritis virus (EAV). The product of ORF6, the second 3' terminal ORF, represents a putative membrane protein and exhibits 53.2 and 27.2% amino acid identity with the corresponding LDV and EAV polypeptides, respectively. Similar to EAV, ORFs 2 through 5 might encode glycosylated viral proteins. The polypeptide deduced from the most 5' ORF (ORF1b) contains two conserved domains common to EAV and coronavirus polymerases. Genome organization, strategy of gene expression, and the sequence of deduced proteins show that PRRSV belongs to the Arterivirus group of viruses.
分离出跨越基因组RNA 3'末端5 kb的猪繁殖与呼吸综合征病毒（PRRSV）特异性cDNA克隆，进行测序，并用作鉴定PRRSV特异性RNA的探针。PRRSV基因组是一种约15 kb的正链多聚腺苷酸化RNA。在感染细胞中，可以证明存在一组3'共末端的六个主要亚基因组mRNA。在PRRSV基因组的3'末端3.5 kb范围内，鉴定出六个重叠阅读框（ORF），每个阅读框最有可能由其中一个亚基因组mRNA表达。氨基酸序列比较显示，最3'末端的ORF（ORF7）编码PRRSV核衣壳蛋白，计算分子量为14 kDa。它与乳酸脱氢酶升高病毒（LDV）的衣壳蛋白氨基酸同一性为44.8%，与马动脉炎病毒（EAV）的衣壳蛋白氨基酸同一性为23.6%。3'末端第二个ORF即ORF6的产物代表一种推定的膜蛋白，与相应的LDV和EAV多肽的氨基酸同一性分别为53.2%和27.2%。与EAV相似，ORF 2至5可能编码糖基化病毒蛋白。从最5'的ORF（ORF1b）推导的多肽含有EAV和冠状病毒聚合酶共有的两个保守结构域。基因组组织、基因表达策略以及推导蛋白的序列表明，PRRSV属于动脉炎病毒属病毒。
