2015年、2016年我国部分地区猪群猪繁殖与呼吸综合征的分子流行病学研究

Molecular epidemiologic research of Porcine reproductive and respiratory syndrome virus in pigs in some regions of China from 2015 to 2016

为了解我国部分地区猪繁殖与呼吸综合征病毒（PRRSV）流行毒株的遗传变异情况和流行趋势,试验利用RT-PCR方法对2015年、2016年全国超过20个省份的3 078份疑似PRRS病料进行检测,并扩增部分阳性病料的ORF5基因进行测序和遗传变异分析。结果表明：PRRSV阳性样本共889份,阳性率为28.88%。扩增得到177个ORF5的基因序列,通过序列分析发现,我国流行的PRRSV主要为美洲型,其中90份与高致病性PRRSV（HP-PRRSV）高度同源,53份与经典PRRSV高度同源,34份与NADC30-like PRRSV高度同源,其中14份流行毒株的GP5蛋白糖基化位点N34发生缺失。说明监测地区主要流行HP-PRRSV,同时NADC30-like PRRSV已经形成一个相对独立的分支在我国流行,提示有必要加强PRRSV变异毒株的流行和变异的监测,同时对其致病性等生物学特性进行深入研究。

In order to understand genetic variation and epidemic trends of prevalent strains of Porcine reproductive and respiratory syndrome virus（PRRSV） in some regions of China,RT-PCR method was used in this experiment to determine the virus in 3 078 clinical suspected samples collected from more than 20 provinces of China from 2015 to 2016. ORF5 genes of the isolates from positive samples were amplified and sequenced,and genetic variation analysis was carried out. The results showed that 889 samples were positive for PRRSV,with a positive rate of28. 88%. A total of 177 ORF5 sequences were obtained,and phylogenetic analysis revealed that prevalent PRRSV strains in China were mainly North American type. Among them,90 isolates were highly homologous with high pathogenic PRRSV（HP-PRRSV）,and 53 isolates were highly homologous with classic PRRSV; 34 isolates had an high homology with NADC30-like strain,and the deletion of glycosylation site N34 of GP5 proteins from 14 isolates appeared. The results suggested that prevalent PRRSV isolates in surveillance regions were HP-PRRSV,and NADC30-like strains were classified into a relatively independent branch prevalent in China. The results also indicated that it is necessary to strengthen the monitoring of the prevalence and the variation of PRRSV variant isolates,and the deep research on its biological characteristics such as the pathogenicity.