2016—2018年四川地区猪流行性腹泻病毒流行病学调查与ORF3、S1部分基因序列分析

为分析四川地区猪流行性腹泻流行状况及分子遗传演化特征,对2016年6月至2018年6月收集的71份猪腹泻病例进行RT-PCR检测与相关的流行病学调查,并对其中4份阳性样品进行ORF3、S1基因的检测与序列分析。结果显示,近2年的发病高峰日分别在1月28日和2月11日,发病高峰期在12月至3月;猪场连年感染数量下降,新疫源地增加;ORF3基因可分为2个基因型,部分毒株发生少量碱基突变;从S1基因高变区段分型结果显示,2016年底至2018年初流行的PEDV毒株为GⅡ群,与目前流行的PEDV变异毒株在同一分支,同源性为92.8%~99.3%,碱基变异数量较大,与国内的经典疫苗株CV777亲缘关系较远,同源性为82.7%~87.3%,发病时期更集中,较传统PEDV有轻度后移。结果表明,四川地区规模化猪场PED发病率呈下降趋势,对于该病的防控取得初步成效。目前流行PEDV毒株有变异的趋势,为PEDV的防控奠定基础。

Epidemiological investigation of porcine epidemic diarrhea virus and sequence analysis of ORF3 and S1 genes in Sichuan from 2016 to 2018

To analyze the prevalence and molecular genetic evolution of pig epidemic diarrhea in Sichuan, this study conducted RT-PCR and related epidemiological investigations on 71 cases of diarrhea collected from June 2016 to June 2018, and ORF3 and S1 genes of four positive samples were tested and sequenced. The results showed that the peak incidence days in the past two years were January 28 and February 11, respectively, and the peak incidence period was from December to March. The number of infections in pig farms decreased year by year, and the new epidemic source increased. ORF3 gene can be divided into two genotypes, some strains had a small number of base mutations. The results of S1 gene high-variation segmentation showed that the prevalent PEDV strain from 2016 to 2018 was the GII group, which was the same as the current popular PEDV variant strain. The homology was 92.8%~99.3% and the number of base variation was large. The relationship with the domestic classic vaccine strain CV777 was far and the homology was 82.7%~87.3%. The incidence period was more concentrated than the traditional PEDV. The results showed that the incidence of PED in large-scale pig farms in Sichuan showed a downward trend, and preliminary results were obtained for the prevention and control of the disease. The current trend of PEDV strains was mutated. This study could lay the foundation for the prevention and control of PEDV.