2016-2024年云南省PRRSV分子流行病学调查及ORF5基因遗传进化分析OA

[Objective]This study aimed to understand the prevalence and genetic variation characteristics of Porcine reproductive and respiratory syndrome virus(PRRSV)in Yunnan province,and provide a theoretical basis for the prevention and control of PRRSV in Yunnan province.[Method]From 2016 to 2024,13 803 samples were collected from 16 prefectures in Yunnan.ORF7 gene was amplified by Real-time quantitative PCR to identify PRRSV-positive samples.Global and local spatial autocorrelation analyses were employed to elucidate the spatiotemporal distribution characteristics of the virus.Subsequently,ORF5 gene of positive samples was amplified by RT-PCR.The ORF5 gene sequences from selected representative virus strains and 8 Yunnan isolates retrieved from NCBI,were subjected to analysis of genetic evolution,sequence similarity,variation characteristics of their encoded amino acids,and N-glycosylation sites.[Result]From 2016 to 2024,the positive rate of PRRSV in Yunnan province was 2.67%(369/13 803).Global spatial autocorrelation analysis indicated that the PRRSV positivity rate in Yunnan province was randomly distributed,while local spatial autocorrelation analysis revealed that the significant clustering areas exhibited dynamic changes.Genetic evolution analysis based on ORF5 gene showed that all 16 representative virus strains obtained in this study,and the 8 Yunnan isolates,were classified as PRRSV-2,clustering into Lineage 8(15 strains),Lineage 1(4 strains),Lineage 3(3 strains),and Lineage 5(2 strain).The nucleotide sequence identity of the 24 PRRSV strains ranged from 80.5%to 99.7%,and the amino acid sequence identity ranged from 75.8%to 99.5%.Amino acid mutation analysis indicated that the decoy epitope region had V27A,L28P,V29A,and N30S mutations in Lineage 1,3,and 5 strains.The neutralizing antigenic epitope region had H38Y and L39S/I mutations in Lineage 1,3,and 8 strains.7 strains possessed virulence sites R13 and R151.Additionally,Lineage 1 gained N-glycosylation sites at amino acid positions 30-32,32-34,33-35 and 57-59,with a loss of NGT at positions 51-53.Lineage 8 gained N-glycosylation sites at positions 33-35 and 34-36,with a loss NSS and NLT at positions 35-37 and 44-46.[Conclusion]From 2016 to 2024,the PRRSV positivity rate in Yunnan province was<10%.The global spatial distribution was random,while local clustering exhibited dynamic shifts over time.The prevalent virus strains exhibited co-circulation of multiple lineages,with Lineage 8 identified as the predominant epidemic lineage.Amino acid sites and N-glycosylation sites in the ORF5 gene exhibited varying degrees of variation.It was essential to strengthen continuous epidemiological surveillance and implement more targeted prevention,control,and early warning measures.