2016—2019年山东省仔猪腹泻病原调查及PEDV分离株S基因遗传进化分析

Investigation on the pathogen of diarrhoeal disease of piglets and genetic evolution analysis of S gene of PEDV isolates in Shandong Province from 2016 to 2019

本研究于2016年6月至2019年3月从山东省部分地区收集了231例疑似猪流行性腹泻(PED)病猪样品,患病仔猪主要临床症状为发热、呕吐、水样腹泻、体质量减轻和脱水,并有较高的病死率。通过PCR/RT-PCR对样品进行相关腹泻病原检测。检测结果显示,猪流行性腹泻病毒(PEDV)阳性病料147份,阳性率为63.63%;猪圆环病毒2型(PCV2)检出率为16.88%(39/231);猪轮状病毒(PoRV)检出率为5.19%(12/231),猪传染性胃肠炎(TGEV)检出率为0.43%(1/231)。本研究分离到7株PEDV,对其S基因序列进行遗传进化分析,结果显示,分离株与PEDV参考株的核苷酸序列同源性为93.1%~98.9%,氨基酸序列同源性为91.5%~98.7%。分离株与疫苗株CV777有不同程度的核苷酸和氨基酸位点突变,部分突变氨基酸位点位于PEDV抗原表位区域(COE)和抗原表位S1D5、S1D6中。本研究结果表明vPEDV在山东省广泛流行,是引起仔猪腹泻的主要病原因素,研制新型PEDV疫苗已迫在眉睫。

Diarrhea is the most common disease in piglets,which can be caused by a variety of pathogens,among which porcine epidemic diarrhea virus(PEDV)is the most common.In this study,231 samples of pigs suspected of porcine epidemic diarrhea(PED)disease were collected from June 2016 to March 2019 in Shandong Province.The main clinical symptoms of the diseased piglets were fever,vomiting,watery diarrhea,body mass loss and dehydration,and the mortality of sick piglets was high.The pathogens of diarrhea in the samples were detected by PCR/RT-PCR.The test results showed that the positive rate of PEDV was 63.63%,the detection rate of porcine circovirus type 2(PCV2)was 16.88%,the detection rate of porcine rotavirus(PoRV)was 5.19%,and the detection rate of TGEV was 0.43%.7 strains of PEDV were isolated for genetic evolution analysis of their S gene sequences.the results showed that the nucleotide sequence homology and amino acid sequence homology between the isolated strain and the PEDV reference strain were 93.1%,98.9%and 91.5%,respectively.There were mutations in nucleotide and amino acid sites in CV777 between isolates and vaccine strains in different degrees,and some of the mutated amino acid sites were located in(COE),S1 D5 and S1 D6 of PEDV antigen epitope region.The results of this study show that vPEDV is widely prevalent in Shandong Province and is the main pathogen causing diarrhea in piglets.It is urgent to develop a new type of PEDV vaccine.