Cloning and Phylogenetic Analysis of Nsp2 Gene of PRRSV Tianjin Isolates

To study the variation of procine reproductive and respiratory syndrome virus(PRRSV),three PRRSV isolates(TJ-S1,TJ-S2 and TJ-S3) were obtained from Tianjin province's pig farms.A pair of primers were designed according to the published sequence of Nsp2 gene of BJ-4 strain and used to amplify the partial Nsp2 gene by RT-PCR,the PCR products were cloned into pGEM-T vector and then sequenced.The sequence was analyzed by DNAstar software.Sequence and phylogenetic analysis showed that all these 3 isolates belong to the North American genotype,TJ-S1 strain and TJ-S2 strain shared a common feature of distinctive deletions in 221 and 272-300 amino acids.The phylogenetic tree revealed that TJ-S1 strain,TJ-S2 strain had close relationship with HuN strain and SD-14 strain,TJ-S3 was close to CH-1a.