2020—2022年闽粤赣地区PRRSV ORF5基因的分子流行病学调查

Molecular epidemiological survey of PRRSV ORF5 gene in Fujian,Guangdong and Jiangxi regions from 2020 to 2022

【目的】了解闽粤赣地区猪繁殖与呼吸综合征病毒(PRRSV)的分子流行动态,为该疫病的科学防控提供参考。【方法】采用实时荧光定量PCR(qRT-PCR)方法对2020—2022年闽粤赣地区1475份临床猪组织和血清样品进行检测,对PRRSV阳性样品进行ORF5基因扩增和测序,并对ORF5基因的序列进行系统发育分析。【结果】2020、2021、2022年闽粤赣地区发病猪PRRSV的阳性率分别为24.23%(95/392)、27.69%(162/585)、18.07%(90/498),2020—2022年福建、广东、江西地区PRRSV的阳性率分别为23.20%(272/1172)、23.96%(52/217)、26.44%(23/87)。挑选来自不同猪场的86份阳性样品进行PCR扩增,成功获得62株PRRSV ORF5基因序列,并下载GenBank已发布的18株2020—2022年闽粤赣地区PRRSV的ORF5基因序列,与127株PRRSV国内外参考株ORF5基因序列构建系统发育树。系统发育树显示,80株闽粤赣PRRSV分离株均属美洲株。其中,40株分布在谱系1(NADC30-like株、NADC34-like株)上,12株分布在谱系3(GM2-like株、QYYZ-like株)上,7株分布在谱系5(VR2332-like株、BJ-4-like株)上,21株分布在谱系8(JXA1-like株、CH-1a-like株)上。对核苷酸和氨基酸序列的同源性进行分析,结果显示,80株PRRSV ORF5基因编码的核苷酸序列同源性为81.2%~100%,氨基酸序列同源性为78.6%~100%。33株PRRSV ORF5基因编码的GP5蛋白氨基酸序列在中和表位区第39氨基酸残基处存在变异。【结论】2020—2022年闽粤赣地区PRRSV流行株以谱系1为主(50.00%),并存在谱系1、3、5、8的混合流行。

【Objective】To investigate the molecular epidemiological dynamics of porcine reproductive and respiratory syndrome virus(PRRSV)in regions across Fujian,Guangdong and Jiangxi Provinces and to provide a reference for the scientificprevention and control of the disease.【Method】1475 clinical porcine tissue and serum samples from these regions during 2020-2022 were detected by real-time fluorescent quantitative PCR(qRT-PCR).And the ORF5 gene in PRRSV-positive samples was amplified and sequenced for phylogenetic analysis.【Result】The PRRSV-positive rates were 24.23%(95/392),27.69%(162/585)and 18.07%(90/498)from 2020 to 2022,and that in Fujian,Guangdong and Jiangxi reached 23.20%(272/1172),23.96%(52/217)and 26.44%(23/87),respectively.The ORF5 gene sequences of 62 PRRSV strains were obtained by PCR from 86 PRRSV-positive samples selected from different pig farms.These sequences were subject to phylogenetic analysis with the GenBank sequences of ORF5 gene of 18 strains from Fujian,Guangdong and Jiangxi during 2020-2022 and the ORF5 gene sequence of 127 PRRSV reference strains at home and abroad.Phylogenetic tree analysis showed that all the 80 PRRSV strains from the regions belonged to American strains,among which 40,12,7 and 21 strains were distributed in lineage 1(NADC30-like strain and NADC34-like strain),lineage 3(GM2-like strain and QYYZ-like strain),lineage 5(VR2332-like strain and BJ-4-like strain),and lineage 8(JXA1-like strain and CH-1a-like strain),respectively.The ORF5 genes of the 80 PRRSV showed nucleotide sequence homology of 81.2%-100%,and the proteins they encoded showed amino acid sequence homology of 78.6%-100%.GP5 protein encoded by ORF5 gene of 33 PRRSV strains had variation at the 39th amino acid residue of the neutralizing epitope.【Conclusion】The prevalent PRRSV strains in Fujian,Guangdong and Jiangxi in 2020-2022 were dominated by spectrum 1(50.00%),and there were mixed epidemics of spectrum 1,3,5 and 8.