2018—2019年广东省猪流行性腹泻病毒S1、M和ORF3基因遗传进化分析

Genetic evolution analysis of Porcine epidemic diarrhea virus S1, M and ORF3 genes in Guangdong province from 2018 to 2019

为了了解2018—2019年广东省猪流行性腹泻病毒(Porcine epidemic diarrhea virus, PEDV)的遗传变异情况,试验采用RT-PCR方法对采集到的69份样品进行PEDV抗原检测,并对部分阳性样品的S1、M和ORF3基因进行测序,再利用分子生物学软件对测序结果与NCBI中的参考毒株进行遗传进化树的构建、同源性分析及氨基酸序列比对。结果表明:经RT-PCR检测有38份样品为PEDV阳性,阳性率为55%,阳性率较高。在PEDV S1基因遗传进化分析中,检测毒株均位于G2分支,与VN-VAP1113核苷酸序列同源性较高,为96.0%~97.6%;主要有3个氨基酸缺失、5个氨基酸插入及多个氨基酸突变。在PEDV M基因遗传进化分析中,GDxh毒株位于G1-2分支,与DR13核苷酸序列同源性较高,为98.3%;GDhz-1毒株位于G2-1分支,与VN-VAP1113核苷酸序列同源性较高,为98.3%;其他12株毒株位于G2-2分支,与OH851核苷酸序列同源性较高,为97.4%~99.1%;主要有5个氨基酸突变和1个氨基酸插入。在PEDV ORF3基因遗传进化分析中,GDxh毒株与DR13核苷酸序列同源性为91.6%,主要有4个氨基酸突变和一段氨基酸缺失;其他检测毒株均位于G2分支,其中7株毒株与OH851核苷酸序列同源性为90.2%~92.0%,主要有5个氨基酸突变;另外5株毒株与VN-VAP1113核苷酸序列同源性均为87.6%,主要有11个氨基酸突变。说明2018—2019年广东省PEDV流行毒株主要为G1型和G2型,流行情况复杂,其S1和ORF3基因对应的氨基酸序列容易发生突变、插入或缺失,给该地区猪流行性腹泻的防治工作带来较大挑战。

In order to understand the genetic variation of Porcine epidemic diarrhea virus(PEDV) in Guangdong province from 2018 to 2019, RT-PCR was used to detect the PEDV antigen in 69 samples collected in the experiment, and S1, M and ORF3 of some positive samples were sequenced, and the sequencing results were constructed with reference strains for evolutionary tree construction, homology analysis, and amino acid sequence alignment. The results showed that 38 samples were positive for PEDV by RT-PCR, with a positive rate of 55%. In PEDV S1 genetic evolution analysis, the detected strains are distributed in the G2 branch, and have higher homology with VN-VAP1113, about 96.0%-97.6%, with 3 amino acid deletions, 5 amino acid insertions, and multiple amino acid mutations. In PEDV M genetic evolution analysis, the GDxh strain is distributed in the G1-2 branch, with DR13 homology was 98.3%. GDhz-1 strain is distributed in the G2-1 branch, with VN-VAP1113 homology was 98.3%. The other 12 detected strains are distributed in the G2-2 branch and have higher homology with OH851, which are 97.4%-99.1%, there are mainly 5 amino acid mutations. In PEDV ORF3 genetic evolution analysis, the GDxh strain is distributed in the G1 branch, with DR13 homology was 91.6%, there are 5 amino acid mutations and deletion of an amino acid fragment. Other test strains were all located in G2 branch, among which 7 strains showed homology of OH851 nucleotide sequences ranging from 90.2% to 92.0%, mainly with 5 amino acid mutations. The other five strains were all 87.6% homologous to the nucleotide sequence of VN-VAP1113, and had 11 major amino acid mutations. These results indicate that the epidemic strains of PEDV in Guangdong province are mainly G1 and G2, and the epidemic situation is complex.These phenomena bring great challenges to the prevention and control of porcine epidemic diarrhea in this region.