猪群腹泻症候群病原和病因研究

发布时间：2018-06-01 00:50

本文选题：猪群腹泻流行病学 + 病毒性腹泻　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：自2010年以来,我国猪群发生了重大腹泻,给我国养猪业造成了巨大的经济损失。为了掌握引起我国猪群腹泻症候群的病原与病因,对现有的防疫策略进行简要评估及该病的防疫政策提供技术支撑。本研究采用调查表的形式对2013~2014年我国华北、东北、西北和西南四个地区16个省份2456个规模猪场进行猪群腹泻流行病学调查,随机选取2013~2014年间河北等9个省份63份腹泻粪便及病料,应用PCRRT-PCR技术对我国猪群腹泻症候群病原学中PEDV、TGEV、Po RV、PRV四种常发的病毒性腹泻病毒进行检测,应用Vero细胞对检测呈阳性的病料进行病毒分离,用RT-PCR方法进行PEDV S基因序列扩增,分析主要引起猪群病毒性腹泻病PEDV的S基因的变异情况。结果表明:2013年至2014年两年间我国华北、东北、西北和西南四个区域的腹泻发病略呈下降趋势,但该病仍是猪群最严重的疾病,造成养殖场损失最主要的原因,其病死率仍较高,西南地区养殖场腹泻发病率较其他地区高,仔猪仍然是发病和死亡的主要群体,腹泻的发病期主要集中在秋冬及春季,养殖场规模越大,发生腹泻的风险越小,从疫苗的临床调查结果分析,活疫苗相对灭活苗的效果较好;目前我国猪群腹泻病原比较复杂,以病毒性腹泻病原为主,其中以PEDV为主,Po RV、PRV和TGEV次之,以两种病原混合感染为主,PEDV+PRV高达9.52%,三种病的混合感染次之;通过对PEDV分离鉴定,共得到32个PEDV S基因序列,其核苷酸同源性为88.5%~100%,氨基酸同源性为83.5%~100%,系统进化分析,GD3毒株划到了经典毒株CV777、DR13等G2大分支中,其余31株流行毒株处于G1进化分支,与经典的疫苗毒株距离相对较远,对流行毒株进行基因遗传变异分析,其在不同位点发生了氨基酸的突变和缺失。本研究从猪群腹泻流行病学、猪群主要病毒性腹泻病原和PEDV的遗传和演化的特性及趋势方面揭示腹泻的动态分布,弄清楚腹泻的病原和病因,以期能够为动物疫病预防控制机构和规模猪场防治猪群腹泻病提供可靠的数据和技术支撑。
[Abstract]:Since 2010, great diarrhea has occurred in the pig herd in China, which has caused huge economic losses to the pig industry in our country. In order to understand the pathogen and etiology of swine diarrhea syndrome in China, the current epidemic prevention strategies were evaluated briefly and the technical support of epidemic prevention policy was provided. In this study, 2456 pig farms in 16 provinces of North, Northeast, Northwest and Southwest China were investigated by questionnaire from 2013 to 2014. 63 feces and materials of diarrhea were randomly selected from 9 provinces of Hebei province in 2013 and 2014. The PCRRT-PCR technique was used to detect four common viral diarrhea viruses (PEVV TGEV, Po RV / PRV) in the etiology of swine diarrhea syndrome in China. Vero cells were used to isolate the positive samples and RT-PCR method was used to amplify the PEDV S gene sequence. The variation of S gene which mainly caused the porcine viral diarrhea disease PEDV was analyzed. The results showed that the incidence of diarrhea in four regions of North China, Northeast, Northwest and Southwest of China decreased slightly from 2013 to 2014, but the disease was still the most serious disease in pig herd, the main cause of the loss of breeding farm, and the fatality rate was still high. The incidence of diarrhea in farms in southwest China is higher than that in other areas. Piglets are still the main groups of morbidity and mortality. The incidence of diarrhea mainly occurs in autumn, winter and spring. The larger the scale of farms, the lower the risk of diarrhea. The results of clinical investigation showed that the live vaccine was more effective than inactivated vaccine, and that the pathogen of diarrhea in swine population in our country was complicated at present, the main pathogen was viral diarrhea, among which PEDV was the main pathogen, and TGEV and PEDV were the second. PEDV PRV was as high as 9.52, followed by mixed infection of three diseases, and 32 PEDV S gene sequences were obtained by isolation and identification of PEDV. The nucleotide homology of GD3 strain and amino acid homology of GD3 strain were 88. 5% and 83. 5%, respectively. Phylogenetic analysis showed that GD3 strain was classified into large branches such as classical strain CV777, DR13, and the remaining 31 strains were in G1 evolution branch, which was relatively far away from classical vaccine strain. The mutation and deletion of amino acids occurred at different sites. This study revealed the dynamic distribution of diarrhea from the epidemiology of diarrhea in pigs, the genetic and evolutionary characteristics and trends of the main viral diarrhea pathogens and PEDV in swine herd, and found out the pathogeny and etiology of diarrhea. It is expected to provide reliable data and technical support for the prevention and control of animal epidemic disease and the prevention and control of diarrhea disease in pigs on large scale pig farms.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S858.28

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