2020年我国部分地区猪繁殖与呼吸综合征分子流行病学调查

Molecular Epidemiological Investigation on PRRS in 2020 in Some Regions of China

为了解我国猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)的流行及遗传变异情况,2020年对来自7个省的570份疑似PRRSV感染样品进行RT-PCR检测,并对60个PRRSV阳性样品进行ORF5基因测序及分析比较。RT-PCR检测结果显示,2020年送检样品中,PRRSV阳性检出率为23.68%(135/570),其中保育猪病料的阳性检出率最高,为32.24%(108/335)。同源性对比及遗传进化分析结果显示,60个PRRSV均为PRRSV2(美洲株),主要属于谱系1和谱系8,占比分别为51.67%和43.33%。氨基酸分析结果显示,60个PRRSV的GP5蛋白氨基酸以点突变为主,其中10个PRRSV的GP5蛋白氨基酸出现缺失突变,且非中和表位、中和表位、潜在毒力位点及N-糖基化位点均发生不同程度的变异。结果表明,保育猪群为PRRSV高发病群体,谱系1 PRRSV或已成为国内流行优势毒株,且PRRSV不断发生变异,这或许会影响现有疫苗的免疫保护效果。因此,针对PRRS需要综合防控,除选用安全有效的PRRSV弱毒活疫苗进行免疫外,加强猪场生物安全及饲养管理也极其重要。

In order to investigate the prevalence and molecular genetic variation of porcine reproductive and respiratory syndrome virus(PRRSV)in some regions of China in 2020,570 suspected PRRSV infected samples collected from 7 provinces were detected by RT-PCR,and the ORF5 gene of 60 PRRSV positive samples were sequenced and analyzed.The results showed that,by RT-PCR,the positive rate of PRRSV was 23.68%(135/570),and highest in nursing pigs,which was 32.24%(108/335). It was shown that,by the results of homology comparison and genetic evolution analysis,all the 60 PRRSV were PRRSV2(American strains)and mainly belonged to lineages 1 and 8,accounting for 51.67% and 43.33%,respectively. It was shown that,by the results of amino acid analysis,point mutations were dominant in the GP5 protein amino acid of all the 60 PRRSV,deletion mutations were observed in 10 PRRSV thereof,and variations were observed in non-neutralizing epitopes,neutralizing epitopes,potential virulence sites and N-glycosylation sites to different extent. In conclusion,nursing pigs were highly susceptible to PRRSV. Lineages 1 PRRSV might have become a dominant strain in China,and the immune protection effect of current vaccines might be affected by constantly variation of the virus. Therefore,in addition to vaccination with safe and effective attenuated live vaccines,biosafety and feeding management on farms had also played an important role in prevention and control of PRRSV.