猪繁殖与呼吸障碍综合征病毒感染状态与抗体水平关联性分析

Relationship analysis between antibody level and infection status of porcine reproductive and respiratory syndrome virus

为了深入了解猪繁殖与呼吸障碍综合征病毒(PRRSV)感染状态与血清中抗体水平的关联性,本研究选择新疆北疆地区3个PRRSV防控方法不同的规模化猪场,使用ELISA和qRT-PCR对各个阶段猪群血清中PRRSV抗体水平和抗原阳性率进行了为期2年的持续监测,并通过ORF5基因测序对其中2个猪场PRRSV流行毒株进行了初步确定。结果表明,在猪群整体生产性能处于较高水平时,免疫PRRSV MLV猪场种猪群抗体阳性率应≥90.0%,S/P值离散度≤40.0%,S/P值≥2.5比例为0;商品猪群抗体阳性率应≥85.0%,S/P值离散度≤50.0%,S/P值≥2.5比例<5.0%,不同时期抗体S/P值平均值应在0.4~2.5且保持相对稳定。PRRSV自然感染的猪场,待猪群生产性能稳定后,PRRSV抗体阳性率、S/P值平均值以及S/P值≥2.5的样本数量应呈逐步下降趋势。PRRSV抗体S/P值在0.4~2.5的血清样本,使用qRT-PCR均未检测到PRRSV抗原;S/P值在2.6~3.0的血清样本,PRRSV抗原阳性率为15.0%~54.0%,而S/P>3.1的血清样本,PRRSV抗原阳性率为78.0%~100.0%。调查猪场感染PRRSV毒株为JXA1和CH-1a毒株。本研究为猪场科学解读PRRSV抗体ELISA检测结果,评估猪群PRRSV稳定状态,进而合理制定PRRSV防控策略提供依据。

The aim of this study is to understand the relationship between antibody level and infection status of porcine reproductive and respiratory syndrome virus(PRRSV).Three swine farms which applied different methods to control PRRSV were chosen,and the antibody and antigen in serum of different swine herd were detected by ELISA and qRT-PCR for two years.The prevalent strains of two farms were determined by sequencing the ORF5gene of PRRSV.The result showed that,when the overall production performance of swine herd kept on a relative higher level,in swine herd immunized with PRRSV MLV,the antibody positive rate of breeding swine was equal or greater than 90.0%,the variation of S/P was equal or less than 40.0%,and the proportion of S/P which was equal or greater than 2.5was zero,the antibody positive rate of fatten swine was equal or greater than 85.0%,the variation of S/P was equal or less than 50.0%,and the proportion of S/P which was equal or greater than 2.5was greater than 5.0%,and the mean value of antibody S/P of swine herd was among 0.4to 2.5.For swine farm which controlled PRRSV by natural infection,the antibody positive rate,the mean value of antibody S/P,the proportion of S/P which was equal or greater than 2.5showed a downward trend when the overall production performance of swine herd kept on a relative higher level.For the serum samples with antibody S/P between 0.4to 2.5,the PRRSV antigen could not be detected by qRT-PCR;for serum samples with S/P value between 2.6and 3.0,the positive rate of PRRSV antigen was 15.0%to 54.0%;for the serum samples with antibody S/P was greater than 3.1,the positive rate of PRRSV antigen was 78.0%to 100.0%.The prevalent strains were JXA1and CH-1ain these swine farm.This investigation can help to understand ELISA detection result of PRRSV antibody,assess steady state of swine herd PRRSV,and finally formulate reasonable PRRSV control strategy.