2014-2017年中国部分地区PEDV流行株S基因遗传进化分析

参考GenBank中PEDV经典CV777毒株基因组序列设计特异性引物，采用RT-PCR方法对临床采集的疑似PEDV样品进行S基因扩增、克隆和测序，拼接获得30条完整S基因序列，并进行遗传进化及同源性分析。结果显示，获得的30条PEDV S基因与25个参考株S基因的核苷酸相似性介于93.6%～99.8%；且各流行毒株与经典毒株比较，具有多处的点突变、插入和缺失。与其他参考株相比，S1区存在157个氨基酸突变位点，占总数的65.7%（157/239），暗示PEDV的 S1区域比S2区域易发生变异；表明目前中国PEDV流行株已经发生了变异，在一定程度揭示了免疫猪群仍然发病的原因。

Phylogenetic analysis of S gene of porcine epidemic diarrhea virus from some districts of China during 2014-2017

To understand the genetic variation of the prevalent PEDV strains, specific primers were designed based on the genome sequence of the PEDV classical CV777 strain in GenBank. The S genes were amplified by RT-PCR from clinically suspected PEDV samples, and 30 complete sequences of S gene were obtained by sequencing and splicing. Further genetic evolution and homology analysis results showed S genes of the strains in this study had 93.6 to 99.8% nucleic acid sequence similarity to S gene of 25 reference strains, and each strain had multiple point mutations, insertions, and deletions. There were 157 amino acid mutations in S1 region, which accounted for 65.7% (157/239) of the total number of S gene mutation sites, indicating that the PEDV S1 region was more variable than the S2 region. Comparison of the deduced amino acid sequence of the S protein between each strain and the reference strain showed that the current PEDV epidemic strains have been mutated, and it has revealed to a certain extent the reason why the immune pig herd is still onset in China.