猪繁殖与呼吸综合征病毒强毒株HUB2株全基因组序列分析

Full-length genome analysis of hyper-virulent isolate HUB2 of porcine reproductive and respiratory syndrome virus

从湖北省暴发猪“高热病”的猪场分离出1株猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus，PRRSV），并命名为HUB2株。根据GenBank上已发表的PRRSV全基因序列设计引物进行RT—PCR扩增，获得PRRSV HUB2株全基因组cDNA序列。测序结果表明PRRSV HUB2株基因组全长15320bp（不包括PolyA尾）。分析结果显示该毒株与PRRSV美洲型标准株（VR-2332）和欧洲型标准株（LV）全基因核苷酸同源性分别为89．6％和50．3％，说明HUB2属于美洲型毒株。与VR-2332相比，HUB2株非结构蛋白（Nsp2）存在2处不连续的缺失（共缺失30个氨基酸），其缺失位点位于推定氨基酸序列的第481位和532～560位。此次新出现的强毒株全基因组序列特性的揭示为科学防治猪高致病性蓝耳病奠定了理论基础。

One porcine reproductive and respiratory syndrome virus （PRRSV） isolate designated as HUB2 was obtained from HuBei province in China in 2006, where had broken out so-called ＂high fever＂ disease. According to some PRRSV sequences in GenBank, primers were designed for amplifying the HUB2 isolate full-length genome with RT-PCR protocol. Furthermore, the genome cDNA was sequenced and analyzed. The length of genome of isolate HUB2 was 15 320 nucleotides, noexcluding polyadenylated tail. Phylogenetically, the full-length genomic of the HUB2 strain shared 89.6% and 50.3% nucleotide identity with prototype North American strain VR-2332 and European strain Lelystad, respectively. Hence this new Chinese isolate was of North American genotype lineage. Strikingly, two novel discontinuous deletions（30 amino acids in all） were found in the non-structural protein 2 （nsp2） encoded by ORFla,with 1 and 29 putative amino acids, corresponding to the amino acid positions in PRRSV strain VR- 2332 Nsp2 of 481 and 532-560, respectively. Together, the peculiarity of this new novel hyper-virulent isolate will provide a fundation for control of the hyper-virulent porcine reproductive and respiratory syndrome.