PDF(Pubmed)
Abstract：
Porcine reproductive and respiratory syndrome virus type 2 (PRRSV-2) lineage 8 was first detected in mainland China in 2006 and has since rapidly spread to become the primary epidemic strain in the country. In this study, samples such as lung tissue, hilar lymph nodes, abortion fetuses, and blood were collected from large-scale pig farms across 11 prefecture-level cities in Sichuan province between 2019 and 2020 for antigen detection and PRRS virus isolation. The antigen detection results indicated that the positive rate of HP-PRRSV (JXA1-Like strain) was 44.74% (51/114), NADC30-Like PRRSV was 17.54% (20/114), and classical PRRSV (VR2332-Like strain) was 37.72% (43/114). The predominant strain was HP-PRRSV. Positive samples were further inoculated into Marc-145 cells for virus isolation and identification, leading to the isolation of a new JXA1-Like PRRSV strain named SCSN2020. The strain was characterized by RT-qPCR, indirect immunofluorescence assay (IFA), plaque purification, electron microscopy, and whole genome sequencing. The total length of the viral genome was determined to be approximately 15,374 bp. A comparison of the SCSN2020 genome with VR2332 revealed that both strains had the same discontinuous 30-amino acid deletion on the Nsp2 gene. ORF5 genotyping classified the SCSN2020 strain as sublineage 8.7, with a whole genome sequence identity of 99.34% with JXA1. Furthermore, we evaluated the pathogenicity of the SCSN2020 strain in 28-day-old piglets and observed persistent fever from day 4 to day 10, weight loss started on day 7, dyspnea and severe lung lesions began started on day 14. The results of this study highlight the current PRRSV epidemic situation in Sichuan province and provide a scientific reference for subsequent prevention and control measures.
摘要：
猪繁殖与呼吸综合征病毒2型（PRRSV-2）谱系8于2006年在中国大陆首次检测到，此后迅速传播，成为该国的主要流行毒株。在这项研究中,样本如肺组织，肺门淋巴结,流产胎儿,2019年至2020年期间，从四川省11个地级市的大型猪场采集血液，进行抗原检测和PRRS病毒分离。抗原检测结果表明，HP-PRRSV（JXA1样菌株）的阳性率为44.74％（51/114），NADC30样PRRSV为17.54%(20/114)，经典PRRSV(VR2332样菌株)为37.72%(43/114)。优势菌株为HP-PRRSV。将阳性样品进一步接种到Marc-145细胞中进行病毒分离和鉴定，导致分离出一种名为SCSN2020的新型JXA1样PRRSV菌株。通过RT-qPCR对该菌株进行鉴定,间接免疫荧光分析(IFA)，斑块净化，电子显微镜，和全基因组测序。病毒基因组的总长度确定为约15,374bp。SCSN2020基因组与VR2332的比较表明，两个菌株在Nsp2基因上都具有相同的不连续30个氨基酸缺失。ORF5基因分型将SCSN2020菌株分类为亚谱系8.7，与JXA1的全基因组序列同一性为99.34％。此外，我们评估了SCSN2020菌株在28日龄仔猪中的致病性,观察到第4天至第10天持续发热,第7天开始体重减轻,第14天开始出现呼吸困难和严重肺部病变.本研究结果突出了当前四川省PRRSV流行现状,为后续防控措施提供了科学参考。
