Emergence of novel recombination lineage 3 of porcine reproductive and respiratory syndrome viruses in Southern China
Emergence of novel recombination lineage 3 of porcine reproductive and respiratory syndrome viruses in Southern China
复制标题
猪繁殖与呼吸综合征病毒新重组谱系3在华南地区的出现
DOI：
10.1111/tbed.13067
复制
发表时间：
2019-01-01
影响因子：
4.3
通讯作者：
Wang, Heng
中科院分区：
文献类型：
--
作者：
Sun, Yan-Kuo;Li, Qi;Wang, Heng
猪繁殖与呼吸综合征病毒3系属于北美2型，在我国流行历史较长。近年来不断出现的新3系病毒具有检出率高、致病性强等特点。在这项研究中，我们调查了谱系3在中国南方的流行情况，并选择了两个分离株进行基因组和毒力分析。一项横断面流行病学调查显示，2016年1月至2017年7月在中国南方100多个感染农场采集的227份样本中，谱系3抗原的患病率为35.68%（95%CI：27.6-44.3%）。选择了谱系3的两个新分离物。Marc-145细胞在传代20代后对这些病毒不敏感。基因组全长序列分析表明，两株病毒与高致病性猪繁殖与呼吸综合征病毒（HP-PRRSVs; JXA 1-like strain，lineage 8.7）的同源性为95.2%~ 96.2%。系统发育和分子进化分析结果表明，两株病毒的ORF 1基因大部分由HP-PRRSV提供。动物实验结果表明，不同菌株的毒力存在差异。尽管攻毒导致100%的发病率，但携带大部分HP-PRRSV ORF 1基因的分离株引起严重的临床症状和40%的死亡率，而另一株含有部分ORF 1基因的分离株则没有引起死亡。总体而言，这些发现表明谱系3病毒可能在中国南方大部分地区普遍流行。该谱系的HP-PRRSV内频繁的重组事件以及变化的毒力可能代表对养猪业的潜在威胁。
Lineage 3 of porcine reproductive and respiratory syndrome viruses, which belong to North America type 2, has a long epidemic history in China. The novel lineage 3 viruses constantly emerging in recent years are characterized by a high detection rate and significant pathogenicity. In this study, we investigated the prevalence of lineage 3 in southern China and selected two isolated strains for genome and virulence analyses. A cross-sectional epidemiology investigation indicated that the prevalence of lineage 3 antigens was 35.68% (95% CI: 27.6-44.3%) among 227 samples collected from over 100 infected farms from January 2016 to July 2017 in southern China. Two novel isolates of lineage 3 were selected. After 20 passages, Marc-145 cells were not susceptible to those viruses. Full-length genome analysis indicated that the two strains share 95.2% homology with each other and 95.7%-96.2% with highly pathogenic porcine reproductive and respiratory syndrome viruses (HP-PRRSVs; JXA1-like strain, lineage 8.7). Phylogenetic and molecular evolutionary results showed that for the two isolates, HP-PRRSV provides most of the ORF1 gene. Animal experiment revealed discrepancies in virulence between the strains. Although challenge resulted in 100% morbidity, the isolate carrying most of the HP-PRRSV ORF1 caused severe clinical symptoms and 40% mortality, whereas the other isolate containing part of the ORF1 gene caused no mortality. Overall, these findings suggest that lineage 3 viruses might be commonly circulating in most of southern China. Frequent recombination events within HP-PRRSVs of this lineage with changing virulence could represent potential threats to the pig industry.