哈兽研发现类NADC34 PRRSV与我国地方流行毒株发生重组并快速蔓延
2022年2月19日,国际Top期刊(Transboundary and Emerging Diseases)在线发表中国农业科学院哈尔滨兽医研究所猪病综合防控创新团队和猪免疫抑制病团队2020-2021年我国类NADC34 PRRSV新特征的文章。本研究为我国PRRSV的流行病学及科学防控提供数据。相关论文“Novel characteristics of Chinese NADC34-like PRRSV during 2020-2021”链接如下:https://doi.org/10.1111/tbed.14485。猪繁殖与呼吸综合征病毒(Porcine reproductive and respiratory syndromevirus, PRRSV)是引起猪繁殖与呼吸综合征(PRRS)的病原,对全球养猪业造成严重的经济损失,2017年猪病综合防控创新团队张洪亮博士首次在中国发现类NADC34 PRRSV,并进一步发现其具有流行潜力。由于类NADC34 PRRSV在美国、秘鲁等地持续流行,并已经在国内出现,严重威胁我国养猪业。田志军团队长期对类NADC34 PRRSV的流行情况进行监测。结果显示近年来类NADC34 PRRSV检出比例持续增加,2017-2019年,这类毒株的阳性占比不到3%,2020年飙升至11.5%,2021年达到惊人的28.6%,已经与NADC30-like(35.4%)和HP-PRRSV(31.2%)一同成为我国部分地区的主要流行毒株之一。随着病例的增多,该类毒株也逐渐由起初的3个省扩散至8个省。遗传演化分析表明,目前中国的类NADC34毒株与美国sublineage 1.5毒株同源较高,但未形成独立分支,这也预示着类NADC34毒株的快速蔓延不仅是来自于国内毒株的扩散,可能同时存在国外毒株的输入。重组分析显示,部分新发类NADC34 PRRSV与中国本土的类NADC30和类HP-PRRSV发生了复杂的重组。猪病综合防控创新团队首席科学家田志军研究员指出,这是首次报道类NADC34 PRRSV与我国地方流行毒株发生重组,重组毒株出现的时间与该类毒株检出率骤增的时间相吻合,因此与国内流行毒株的重组,可能是导致类NADC34毒株在我国快速蔓延的原因之一。由于重组毒株的出现,部分毒株在Nsp2区域出现了与NADC30毒株相同的131-aa不连续缺失,其余毒株与IA/2014/NADC34毒株的缺失模式相同。鉴于类NADC34毒株已在我国快速流行,我们需要加大监测力度,采取相应的对策,降低该类毒株对我国养猪业的危害。本研究是在国家自然科学基金(32172890和32002315);中国博士后科学基金(2020M680788);黑龙江省自然科学基金(YQ2019C032和YQ2019C030);兽医国家重点实验室生物技术基金(SKLVBF202115)资助下完成的。许浒博士、李超硕士和李宛生博士为本文共同第一作者。张洪亮博士为通讯作者。(张洪亮,许浒)AbstractNADC34-like porcine reproductive and respiratorysyndrome virus (PRRSV) strains were first detected in China in 2017, withepidemic potential. In this study, the phylogenetic, epidemic, and recombinantproperties of NADC34-like PRRSV in China were evaluated comprehensively. From2020 to October 2021, 82 NADC34-like PRRSV isolates were obtained from 433PRRSV-positive clinical samples. These strains accounted for 11.5% and 28.6% ofpositives in 2020 and 2021, respectively, and have spread to eight provinces.We selected 15 samples for whole-genome sequencing, revealing genome lengths of15,009 to 15,113 nt. Phylogenetic analysis revealed that Chinese NADC34-likestrains cluster with American sublineage 1.5 strains and do not form anindependent branch. Recombination analysis revealed that six of fifteencomplete genome sequences were derived from recombination between NADC34-likeand NADC30-like or HP-PRRSV; all of the strains recombined with local strainsin China, exhibiting a complex recombination pattern. Partial Nsp2 sequencealignment showed that nine of fifteen isolates had a 100-aa continuous deletion(similar to that in IA/2014/NADC34); other isolates had a 131-aa discontinuousdeletion (similar to that in NADC30). Five of them also had additional aminoacid deletions, all of which are reported for the first time here. In the lasttwo years, NADC34-like PRRSV has become one of the main epidemic strains insome areas of China; it has changed significantly, its homology has decreasedsignificantly, and it has undergone complex recombination with local Chinesestrains. These results are of great significance for understanding the currentepidemic situation of PRRSV in China.来源:病毒学界