Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China.
Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China; Tianjin Animal Husbandry, Veterinary Research Institute, Tianjin 300381, People's Republic of China.
Infect Genet Evol. 2017 Oct;54:279-286. doi: 10.1016/j.meegid.2017.07.016. Epub 2017 Jul 13.
Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically important pathogen for swine industry worldwide. The recombination occurring among PRRSV strains has been recognized as one of important molecular mechanisms for the evolution of PRRSV. Current prevalence of PRRSV NADC30-like causing clinical disease outbreaks is highly concerned in China. In the present study, the genetic characterization of a recombinant type 2 PRRSV (designated TJnh1501) was analyzed and its pathogenicity for piglets was examined. Our study showed that each region of TJnh1501 genome had 96.67-100% nucleotide and 96.5-100% amino acid identities with a Chinese highly pathogenic PRRSV-derived modified-live virus (MLV)-like except for its nonstructural protein 2 (nsp2)-coding region; while its nsp2-coding region shared higher nucleotide (84.44-85.85%) and amino acid (82.44-84.79%) identities with NADC30 and NADC30-like CHsx1401, and in particular, the highly variable region of nsp2 exhibited characteristic 131-aa deletion identical to NADC30 and NADC30-like CHsx1401. Meanwhile, we identified two recombination breakpoints located in the nt1737 and nt3506 of nsp2-coding region, which had higher nucleotide homology with NADC30 and NADC30-like CHsx1401. Moreover, TJnh1501 infection could cause persistent fever, moderate respiratory clinical signs, higher viremia, and obvious gross and microscopic lung lesions in piglets. The virus was shown to have lower pathogenicity than HP-PRRSV JXwn06, but higher than NADC30-like CHsx1401 for piglets. Our findings reveal that TJnh1501 is a recombinant type 2 PRRSV from the recombinant event between NADC30-like and MLV-like derived from the Chinese highly pathogenic PRRSV, and it exhibits intermediate virulence for pigs. This study adds valuable evidence for understanding the role of genomic recombination in the evolution of PRRSV.
猪繁殖与呼吸综合征病毒（PRRSV）是全球养猪业的一种重要经济病原体。PRRSV 株间的重组已被认为是 PRRSV 进化的重要分子机制之一。目前，中国高度关注 NADC30 样 PRRSV 引起的临床疾病爆发。本研究分析了一株重组型 2 猪繁殖与呼吸综合征病毒（命名为 TJnh1501）的遗传特征，并检测了其对仔猪的致病性。研究表明，除非结构蛋白 2（nsp2）编码区外，TJnh1501 基因组的每个区域与中国高致病性 PRRSV 衍生的改良活疫苗（MLV）样均具有 96.67-100%的核苷酸和 96.5-100%的氨基酸同一性；而其 nsp2 编码区与 NADC30 和 NADC30 样 CHsx1401 具有更高的核苷酸（84.44-85.85%）和氨基酸（82.44-84.79%）同一性，特别是 nsp2 的高度可变区表现出与 NADC30 和 NADC30 样 CHsx1401 相同的特征性 131-aa 缺失。同时，我们在 nsp2 编码区的 nt1737 和 nt3506 处鉴定出两个重组断点，这些断点与 NADC30 和 NADC30 样 CHsx1401 具有更高的核苷酸同源性。此外，TJnh1501 感染可导致仔猪持续发热、中度呼吸道临床症状、更高的病毒血症和明显的肺部大体和显微镜病变。该病毒的致病性低于 JXwn06 高致病性 PRRSV，但高于 NADC30 样 CHsx1401。我们的研究结果表明，TJnh1501 是一种由 NADC30 样和源自中国高致病性 PRRSV 的 MLV 样之间的重组事件产生的重组型 2 PRRSV，其对猪具有中等毒力。本研究为了解基因组重组在 PRRSV 进化中的作用提供了有价值的证据。
