山东省部分地区猪流行性腹泻流行病学调查及其M基因遗传变异分析

Epidemiological investigation of porcine epidemic diarrhea disease and phylogenetic analysis of M gene of PEDV in Shandong province

自2010年冬季以来，由猪流行性腹泻病毒（PEDV）引起的猪流行性腹泻在山东省部分地区暴发，引起哺乳仔猪严重的呕吐、水样腹泻和脱水，部分规模化猪场的仔猪死亡率高达90％～100％，给山东省养猪业造成了巨大的经济损失。本研究对2012年1月2012年4月山东省德州、泰安、烟台、济宁、济南5个地市的15个·临床表现腹泻症状的规模化猪场进行了病原检测和流行病学调查，并进行了15株PEDV野毒的主要结构蛋白基因M基因的全基因测序测定与分析。结果显示PEDV的个体阳性率为62．86％（44／70），群体阳性率为100％（15／15）；TGEv的个体阳性率为12．86％（9／70），群体阳性率为20％（3／15），表明造成2012年春天山东省规模化猪场仔猪腹泻的主要病原为PEDV，并发或继发TGEV；免疫T—P二联苗的猪场与未免疫猪场的发病率和死亡率没有明显的差别，推测有可能是病毒发生了较大变异。序列分析结果表明15株PEDV野毒的M基因全长均为681nt，相互之间遗传距离较近，处同一分支，与韩国株BIF256，泰国株KU04RB08、KU06RB08、KU07RB08、MNIAH10054208的亲缘关系较近，而与国内2011年分离的SJZ-2011和QY2毒株以及疫苗株cV777的遗传距离较远。

Porcine epidemic diarrhea disease caused by porcine epidemic diarrhea virus （PEDV） has been spreads in swine-breeding farms in parts of Shandong province since the winter of 2010, cau sing serious vomiting,watery diarrhea and dehydration in suckling piglets. The mortality rate var ried from 90% to 100% ,resulting in huge economic losses to the pig industry in Shandong prov ince. In this study,pathogen detection and epidemiological investigation were conducted in 15 scale pig farms which appeared clinical manifestations of diarrhea in Dezhou, Taian,Yantai,Jining,Jinan of Shandong province from January to April 2012. As a major structural protein gene, the M gene was amplified from 15 PEDV-positive stains by RT-PCR, cloned, sequenced and compared with each other. The results showed that the PEDV individual positive rate was 62.86% （44/70） and the groups positive rate was 100% （15/15）. Correspondingly, the TGEV individual positive rate was 12.86% （9/70）,the groups positive rate was 20% （3/15）. The results indicated that PEDV was the major pathogen that caused piglet diarrhea in large-scale pig farms of Shandong province in the spring of 2012. The morbidity and mortality of farms which immunized T-P vaccine didn＇t perform significant differences when compared with that unimmunized ones,suggesting that there may occur variation in PEDV. The sequence analysis showed that the M genes of 15 PEDVfield strains are all have a complete ORF with 681 nt. They have closed genetic distance with each other. Compared with other Chinese isolates and foreign isolates,the 15 isolates showed closer ge- netic relationship with the Korea isolate BIF256 and Thailand isolates KU04RB08, KU06RB08, KU07RB08 and MNIAH10054208,but more distant genetic relationship with Chinese isolates SJZ- 2011 and QY2 isolated in 2011 as well as the vaccine strain CV777.