Laboratory of Animal infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning, 530005, People's Republic of China.
BMC Vet Res. 2019 May 24;15(1):171. doi: 10.1186/s12917-019-1906-9.
Porcine respiratory and reproductive syndrome virus (PRRSV) is one of the most economically significant pathogens in the Chinese swine industry. ORF5 and nsp2 are highly variable regions of the PRRSV genome. Therefore, nsp2 and GP5 are often selected for investigation of variations and phylogenetic analyses for their genetic diversities. Knowledge of the molecular evolution of PRRSV field strains may contribute to the control of PRRS in China.
The results of multiple sequence alignments of GP5 showed that there is 84.5-100% aa identity among the 56 strains in this study. These strains shared 84.5-99.0% aa identity with the prototypical type 2 PRRSV VR-2332 and 56.6-59.2% with strain LV, prototypical type 1 PRRSV. Phylogenetic analysis showed there is considerable diversity among PRRSV ORF5 and the existence of two lineages (5 and 8). Most of the strains were classified into lineage 8 with multiple sub-lineages (3, 4 and 6). Moreover, PRRSV strains with 5 novel patterns of deletions or insertions in the nsp2 region were found.
Phylogenetic analysis based on ORF5 sequences indicated the diversity of PRRSV in southern parts of China and the strains with 30 aa deletion in nsp2 are dominant in the porcine population. Also, new PRRSV strains with different patterns of deletions or insertions in nsp2 are emerging. The data presented here constitute a useful basis for further epidemiological studies regarding the heterogeneity of PRRSV strains in China and provide a basis for the prevention of PRRS in southern parts of China.
猪繁殖与呼吸综合征病毒（PRRSV）是中国养猪业最重要的经济病原体之一。ORF5 和 nsp2 是 PRRSV 基因组中高度可变的区域。因此，nsp2 和 GP5 通常被选择用于调查其遗传多样性的变异和系统发育分析。了解 PRRSV 田间毒株的分子进化可能有助于控制中国的 PRRS。
对 GP5 的多个序列比对结果表明，本研究中的 56 株之间的 aa 同一性为 84.5-100%。这些株与原型 2 型 PRRSV VR-2332 共享 84.5-99.0%的 aa 同一性，与原型 1 型 PRRSV LV 株共享 56.6-59.2%的 aa 同一性。系统发育分析表明，PRRSV ORF5 之间存在相当大的多样性，存在两个谱系（5 和 8）。大多数株分为谱系 8，具有多个亚谱系（3、4 和 6）。此外，还发现了 nsp2 区域具有 5 种新型缺失或插入模式的 PRRSV 株。
基于 ORF5 序列的系统发育分析表明，中国南方地区 PRRSV 的多样性，并且 nsp2 中有 30 个氨基酸缺失的株在猪群中占优势。此外，出现了具有不同缺失或插入模式的新型 PRRSV 株。本研究提供的数据为进一步开展有关中国 PRRSV 株异质性的流行病学研究提供了有用的基础，并为中国南方地区 PRRS 的预防提供了依据。
