College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China.
College of Life Sciences of Longyan University, Longyan, Fujian Province, China.
Transbound Emerg Dis. 2017 Dec;64(6):2059-2074. doi: 10.1111/tbed.12617. Epub 2017 Feb 14.
From 2014 to 2015, four novel highly pathogenic PRRS virus (HP-PRRSV) strains named 14LY01-FJ, 14LY02-FJ 15LY01-FJ, and 15LY02-FJ were isolated from high morbidity (100%) and mortality (40%-80%) in piglets and sows in Fujian Province. To further our knowledge about these novel virus strains, we characterized their complete genomes and determined their pathogenicity in piglets. Full-length genome sequencing analysis showed that these four isolates were closely related to type 2 (North American type, NA-type) isolates, with 88.1%-96.3% nucleotide similarity, but only 60.6%-60.8% homology to the Lelystad virus (LV) (European type, EU-type). The full length of the four isolates was determined to be 15017 or 15018 nucleotides (nt), excluding the poly(A) tail. Furthermore, the four isolates had three discontinuous deletions (aa 322-432, aa 483, and aa 504-522) within hypervariable region II (HV-II) of Nsp2, as compared to the reference strain VR-2332. This deletion pattern in the four isolates is consistent with strain MN184 and strain NADC30 isolated from America. Phylogenetic and molecular evolutionary analyses indicated that these virulent strains originated from a natural recombination event between the JXA1-like HP-PRRSV (JXA-1 is one of the earliest Chinese HP-PRRSV strains; sublineage 8.7) and the NADC30-like (lineage 1) PRRSV. Animal experiments demonstrated that these four strains caused significant weight loss and severe histopathological lung lesions as compared to the negative control group. High mortality rate (40% or 80%) was found in piglets infected with any one of the four strains, similar to that found with other Chinese HP-PRRSV strains. This study showed that the novel variant PRRSV was HP-PRRSV, and it is therefore critical to monitor PRRSV evolution in China and develop a method for controlling PRRS.
从 2014 年到 2015 年，从福建省高发病率（100%）和高死亡率（40%-80%）的仔猪和母猪中分离到了四种新型高致病性猪繁殖与呼吸综合征病毒（HP-PRRSV）毒株，分别命名为 14LY01-FJ、14LY02-FJ、15LY01-FJ 和 15LY02-FJ。为了进一步了解这些新型病毒株，我们对它们的全基因组进行了特征描述，并在仔猪中确定了它们的致病性。全长基因组测序分析表明，这四种分离株与 2 型（北美型，NA 型）分离株密切相关，核苷酸相似性为 88.1%-96.3%，但与 Lelystad 病毒（LV）（欧洲型，EU 型）的同源性仅为 60.6%-60.8%。这四种分离株的全长均为 15017 或 15018 个核苷酸（nt），不包括 poly（A）尾。此外，与参考株 VR-2332 相比，这四种分离株在 Nsp2 的高变区 II（HV-II）内有三个不连续缺失（aa322-432、aa483 和 aa504-522）。这种缺失模式与从美国分离到的 MN184 株和 NADC30 株一致。系统进化和分子进化分析表明，这些毒力株起源于 JXA1 样 HP-PRRSV（JXA-1 是最早的中国 HP-PRRSV 株之一；亚系 8.7）与 NADC30 样（谱系 1）PRRSV 之间的自然重组事件。动物实验表明，与阴性对照组相比，这四种毒株均导致仔猪体重显著减轻和严重的组织病理学肺部病变。感染其中任何一种毒株的仔猪死亡率均为 40%或 80%，与其他中国 HP-PRRSV 株相似。本研究表明，新型变异 PRRSV 为 HP-PRRSV，因此监测中国 PRRSV 的进化并开发控制 PRRS 的方法至关重要。
