Zhang Jianqiang, Guy James S, Snijder Eric J, Denniston Doug A, Timoney Peter J, Balasuriya Udeni B R
Department of Veterinary Science, 108 Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA.
Virology. 2007 Dec 5;369(1):92-104. doi: 10.1016/j.virol.2007.06.035. Epub 2007 Aug 13.
The complete genome sequence of the first equine coronavirus (ECoV) isolate, NC99 strain was accomplished by directly sequencing 11 overlapping fragments which were RT-PCR amplified from viral RNA. The ECoV genome is 30,992 nucleotides in length, excluding the polyA tail. Analysis of the sequence identified 11 open reading frames which encode two replicase polyproteins, five structural proteins (hemagglutinin esterase, spike, envelope, membrane, and nucleocapsid) and four accessory proteins (NS2, p4.7, p12.7, and I). The two replicase polyproteins are predicted to be proteolytically processed by three virus-encoded proteases into 16 non-structural proteins (nsp1-16). The ECoV nsp3 protein had considerable amino acid deletions and insertions compared to the nsp3 proteins of bovine coronavirus, human coronavirus OC43, and porcine hemagglutinating encephalomyelitis virus, three group 2 coronaviruses phylogenetically most closely related to ECoV. The structure of subgenomic mRNAs was analyzed by Northern blot analysis and sequencing of the leader-body junction in each sg mRNA.
首个马冠状病毒（ECoV）分离株NC99株的全基因组序列，是通过对从病毒RNA经RT-PCR扩增得到的11个重叠片段进行直接测序完成的。ECoV基因组长度为30,992个核苷酸，不包括多聚A尾。序列分析确定了11个开放阅读框，它们编码两种复制酶多聚蛋白、五种结构蛋白（血凝素酯酶、刺突蛋白、包膜蛋白、膜蛋白和核衣壳蛋白）以及四种辅助蛋白（NS2、p4.7、p12.7和I）。预计这两种复制酶多聚蛋白会被三种病毒编码的蛋白酶进行蛋白水解加工，形成16种非结构蛋白（nsp1 - 16）。与牛冠状病毒、人冠状病毒OC43和猪血凝性脑脊髓炎病毒（三种在系统发育上与ECoV关系最密切的第2组冠状病毒）的nsp3蛋白相比，ECoV的nsp3蛋白有相当多的氨基酸缺失和插入。通过Northern印迹分析和对每个亚基因组mRNA中前导序列 - 主体序列连接处进行测序，分析了亚基因组mRNA的结构。
