State Key Laboratory of Veterinary Etiological Biology, OIE/National Foot and Mouth Disease Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
Virol J. 2017 Oct 10;14(1):194. doi: 10.1186/s12985-017-0860-z.
Large-scale outbreaks of porcine epidemic diarrhea (PED) have re-emerged in China in recent years. However, little is known about the genetic diversity and molecular epidemiology of field strains of PED virus (PEDV) in China in 2016-2017. To address this issue, in this study, 116 diarrhea samples were collected from pig farms in 6 Chinese provinces in 2016-2017 and were detected using PCR for main porcine enteric pathogens, including PEDV, porcine deltacoronavirus (PDCoV), porcine transmissible gastroenteritis virus (TGEV) and porcine kobuvirus (PKV). In addition, the complete S genes from 11 representative PEDV strains were sequenced and analyzed.
PCR detection showed that 52.6% (61/116) of these samples were positive for PEDV. Furthermore, sequencing results for the spike (S) genes from 11 of the epidemic PEDV strains showed 93-94% nucleotide identity and 92-93% amino acid identity with the classical CV777 strain. Compared with the CV777 vaccine strain, these strains had an insertion (A), a deletion (G), and a continuous 4-amino-acid insertion (NNTN) in the S1 region. Phylogenetic analysis based on the S gene indicated that the 11 assessed PEDV strains were genetically diverse and clustered into the G2 group. These results demonstrate that the epidemic strains of PEDV in China in 2016-2017 are mainly virulent strains that belong to the G2 group and genetically differ from the vaccine strain. Importantly, this is the first report that the samples collected in Hainan Province were positive for PEDV (59.2%, 25/42).
To our knowledge, this article presents the first report of a virulent PEDV strain isolated from Hainan Island, China. The results of this study will contribute to the understanding of the epidemiology and genetic characteristics of PEDV in China.
近年来，中国再次爆发大规模猪流行性腹泻（PED）疫情。然而，对于 2016-2017 年中国田间流行的 PED 病毒（PEDV）的遗传多样性和分子流行病学知之甚少。为了解决这个问题，本研究于 2016-2017 年从中国 6 个省的猪场采集了 116 份腹泻样本，采用 PCR 检测主要的猪肠道病原体，包括 PEDV、猪德尔塔冠状病毒（PDCoV）、猪传染性胃肠炎病毒（TGEV）和猪博卡病毒（PKV）。此外，对 11 株代表性 PEDV 毒株的完整 S 基因进行了测序和分析。
PCR 检测显示，这些样本中有 52.6%（61/116）为 PEDV 阳性。此外，对 11 株流行 PEDV 株的刺突（S）基因进行测序，结果显示其核苷酸同源性为 93-94%，氨基酸同源性为 92-93%，与经典的 CV777 株一致。与 CV777 疫苗株相比，这些毒株在 S1 区有一个插入（A）、一个缺失（G）和一个连续的 4 个氨基酸插入（NNTN）。基于 S 基因的系统进化分析表明，评估的 11 株 PEDV 株遗传多样，聚为 G2 群。这些结果表明，2016-2017 年中国流行的 PEDV 株主要是毒力株，属于 G2 群，与疫苗株遗传不同。重要的是，这是首次报道海南采集的样本 PEDV 阳性（59.2%，25/42）。
据我们所知，本文首次报道了从中国海南岛分离出的一种强毒 PEDV 株。本研究结果将有助于了解中国 PEDV 的流行病学和遗传特征。
