In order to understand the epidemic situation of European porcine reproductive and re-spiratory syndrome virus 1(PRRSV1)in Henan Province,molecular epidemiological investigation and virus identification were conducted on clinical specimens from some large-scale pig farms in Henan Province.RT-PCR detection and sequencing were carried out using specific primers for PRRSVI ORF5 gene.As a result,eight PRRSV1 positive samples were detected with six ORF5 gene sequences and one full gene sequence obtained.A strain of PRRSVI named as HENZMD-10 was successfully isolated using PAM cells.Based on the genetic variation analysis,the six ORF5 genes obtained were all PRRSVI.The isolated strains have relatively large ORF5 gene genetic vari-ation,belonging to different branches on the genetic evolution tree.Among them,HENJZ-11,HENJY-7,and HENJY-8 were relatively close in genetic evolution and belonged to the same branch.The genome length of HENZMD-10 isolate was 15 071 bp.Alignment analysis showed that HENZMD-10 strain shared an 89.1％of nucleotide sequence with the LV strain;62.1％and 61.5％with PRRSV2 ATCC-VR2332 strain and the American NADC30 strain,respectively.The nucleotide similarity of HENZMD-10 strain with the domestic JXA1 strain was 61.6％.The phylo-genetic analysis using complete genome sequence showed that HENZMD-10 strain was relatively close to the domestic isolated PRRSV1 NVDC-NM1-2011,LNEU12 and FJEU13 strains.The suc-cessful isolation of one PRRSV1 strain in Henan Province provides the basis for understanding the epidemic dynamics and prevention and control of PRRSV1 in China.

In order to understand the epidemic situation of European porcine reproductive and re-spiratory syndrome virus 1(PRRSV1)in Henan Province,molecular epidemiological investigation and virus identification were conducted on clinical specimens from some large-scale pig farms in Henan Province.RT-PCR detection and sequencing were carried out using specific primers for PRRSVI ORF5 gene.As a result,eight PRRSV1 positive samples were detected with six ORF5 gene sequences and one full gene sequence obtained.A strain of PRRSVI named as HENZMD-10 was successfully isolated using PAM cells.Based on the genetic variation analysis,the six ORF5 genes obtained were all PRRSVI.The isolated strains have relatively large ORF5 gene genetic vari-ation,belonging to different branches on the genetic evolution tree.Among them,HENJZ-11,HENJY-7,and HENJY-8 were relatively close in genetic evolution and belonged to the same branch.The genome length of HENZMD-10 isolate was 15 071 bp.Alignment analysis showed that HENZMD-10 strain shared an 89.1％of nucleotide sequence with the LV strain;62.1％and 61.5％with PRRSV2 ATCC-VR2332 strain and the American NADC30 strain,respectively.The nucleotide similarity of HENZMD-10 strain with the domestic JXA1 strain was 61.6％.The phylo-genetic analysis using complete genome sequence showed that HENZMD-10 strain was relatively close to the domestic isolated PRRSV1 NVDC-NM1-2011,LNEU12 and FJEU13 strains.The suc-cessful isolation of one PRRSV1 strain in Henan Province provides the basis for understanding the epidemic dynamics and prevention and control of PRRSV1 in China.