广西仔猪腹泻病毒病原流行病学调查

Investigation on epidemiology of piglets diarrhea virus disease in Guangxi

【目的】了解引起广西仔猪腹泻的主要病毒病原及其分子流行病学特点，为其防控提供理论依据。【方法】采用RT-PCR对2011年至2012年7月从广西11个城市的养猪场采集的232份病料进行猪流行性腹泻病毒（PEDV）、猪传染性胃肠炎病毒（TGEV）、猪轮状病毒（PoRV）检测和流行病学调查；对部分PEDV阳性病料的M基因进行克隆，并与国内部分省（市）及国外的一些M基因序列进行比对和遗传进化分析。【结果】广西11个城市采集的232份病料中PEDV、PoRV的阳性率分别为37.50%和0.03%，而TGEV均为阴性。对部分PEDV阳性病料进行M基因扩增，获得14条M基因，其核苷酸同源性及推导氨基酸序列同源性分别为97.4%~100.0%和96.0%~100.0%。将扩增获得的14条PEDV M基因与GenBank上发表的40条国内外PEDV M基因进行比对分析，发现有13条同位于一大支上（G1），其中9条与我国2011年分离获得的广东、四川、江苏参考株及泰国2008年分离获得的5条参考株、韩国2007年分离获得的两条参考株同位于G1-1上，4条与我国2011年分离获得的江西、江苏、广东、福建毒株及江苏2004年分离株JS-2004-2 同位于G1-2上。另外一条PEDV M基因（NNA-11）却与其余13条相距较远，位于G2上。【结论】从2011年至今致使广西仔猪腹泻的病毒主要是PEDV，各市均有不同程度感染，且感染全年存在；大部分广西流行毒株与2011年以来我国广东、福建、江苏、江西四省流行毒株的亲缘性较高，与2007年以来泰国、韩国的流行毒株亲缘关系也非常密切，但与我国2006年前分离获得的北方毒株、经典疫苗株、韩国疫苗株相距较远。

【Objective】This research aimed to understand the main pathogens and molecular epidemiological characteristics of piglets diarrhea virus found in Guangxi in order to provide theoretical basis for piglet diarrhea prevention and control. 【Method】Through the RT-PCR method， the porcine epidemic diarrhea virus （PEDV）， transmissible gastroenteritis virus （TGEV）， and porcine rotavirus （PoRV） from 232 tissue samples collected from the pig farms in 11 cities of Guangxi from 2011 to July 2012 were investigated. Parts of the PEDV positive M gene materials were cloned and analyzed along with the alignments and phylogenetic trees of some M gene sequences from other domestic and international provinces and cities. 【Result】From the 232 tissue samples collected from the 11 cities of Guangxi， the positive rates of PEDV and PoRV were respectively 37.50% and 0.03%， yet the TGEV tested negative. For part of the PEDV positive samples， 14 M genes were obtained after all the M genes were amplified， and the nucleotide homologies of the deduced amino acid sequences were respectively 97.4%-100.0% and 96.0%-100.0%. Comparing and analyzing the 14 PEDV amplified M genes with the 40 PEDV M genes domestically and internationally reported in GenBank， 13 M genes were discovered to be located on a large branch （G1）， out of which 9 were located on the same branch G1-1 as the 5 reference strains isolated and obtained from Guangdong， Sichuan， and Jiangsu in 2011 and Thailand in 2008， and 2 reference strains isolated and obtained from South Korea in 2007. Other 4 M genes were located on the same branch G1-2 as the reference strain JS-2004-2 isolated and obtained from Jiangxi， Jiangsu, Guangdong, and Fujian in 2011and Jiangsu in 2004. The last PEDV M gene （NNA-11）， unlike the others， was located on G2， which was relatively far away from thr other M genes. 【Conclusion】From 2011 until now， the main causes for piglet diarrhea in Guangxi was PEDV， in which the infection degree was different in varying cities, and presence of the infection was year-round. The most prevalent strains in Guangxi exhibited higher affinity with the four Chinese provinces of Guangdong， Fujian， Jiangsu， and Jiangxi since 2011， and the strains were also very closely related to strains found in Thailand and South Korea since 2007， but the stains were far apart from Northern strains， classic vaccinated strains， and Korean vaccinated strains found and isolated since 2006.