猪流行性腹泻病毒云南流行毒株N基因序列分析

Sequence Analysis of N Gene of Porcine Epidemic Diarrhea Virus Epidemic Strains in Yunnan Province

为了解近年来云南省PEDV流行毒株的变异情况，选取了采集自昆明西翥、富源、厂口、玉溪红塔等地方猪场的不同时间的6份PEDV阳性水样腹泻粪便样品，进行N基因的RT—PCR扩增、测序及序列分析。结果表明，来自同一猪场不同流行时间的TY1、TY2、TY3毒株之间，TY1与TY2毒株N基因核苷酸序列完全相同，仅TY3毒株在第80和第1238位置处的碱基发生了变异（A—C、C—T），TY3与TY1、TY2的毒株N基因核苷酸序列的同源性达99．8％。云南6个流行毒株TY1、TY2、TY3、YXHT、FYDH及Changkou的核苷酸序列的同源性为99．2％～100％。云南6个流行毒株与2014年德国毒株GER—L00721—2014（Accession：LM645057．1）、法国毒株KR011756-FR001—2014（Accession：KR011756．1）及我国2010年河北毒株JF700126．1-HB—HS-2010（Accession：LM645057．1）的核苷酸序列同源性为98．6％～100％，并同属于一个进化分支。云南6个流行毒株与CV777经典疫苗毒株之间的同源性仅为95．2％～95．5％，存在一定的变异，这或许是云南省猪群经PEDV疫苗免疫后保护率较低的原因之一。

In order to understand the variation of PEDV epidemic strains in Yunnan Province in recent years, six PEDV positive stool samples, which were collected from four large scale pig farms of different geographical locations and different time, were selected to do RT-PCR, sequencing and sequence analysis. The results showed that nucleotide sequence identity of N gene of TY1, TY2 and TY3 strains was 99.8% , and all this three PEDV strains were collected from the same pig farm in different time. Among them, nucleotide sequence identity of TY1 and TY2 stains was identical, only two mutations had occurr at the 80th and 1238th base pair of N gene sequence of TY3 strain （A→C,C→T）. The TY1, TY2, TY3, YXHT, FYDH, Changkou stains of PEDV collected from Yunnan shared 99.2%-100% nucleotide identity with each other. The six Yunnan epidemic strains and three reference strains of German strain GER-L00721- 2014（Accession. LM645057.1）, French strain KR011756-FR001-2014（Accession. KR011756.1）and Chinese strain JF700126. 1-HB-HS-2010 （Accession. LM645057. 1）shared 98. 6%-100% identity, and they were belong to the same evolutionary branch. The nucleotide identity of N gene of the six PEDV Yunnan strains and traditional PEDV live vaccine CV777 strain was 95.2% to 95.5%. There were some variation between the six PEDV Yunnan epidemic strains and CV777 vaccine strain. This might be one of the reasons why the efficiency of immune protection with CV777 vaccine in pig herds in Yunnan is low.