Abstract: Abstract：Through RTPCR amplification of tissue or blood sample from some of pig form of Huanan area, 14 sequences of the ORF5 gene and 13 sequences of the partail Nsp2 gene were obtained. Sequencing and comparative analysis showed that two sequences exhibited deletion in the Nsp2 gene. There was 96.9% to 99.1% identity between those sequences of Nsp2 gene, sharing 85.1% to 86.4%, 67.2% to 68.9%, 54.1% to 55.9%, 67.6% to 68.9% identity with CH1a, VR2332 LV and MLV respectively. The identity among those sequences of ORF5 gene was 98.8% to 99.7%, sharing 94.4% to 95.2%, 86.7% to 87.9%, 54.1% to 55.7%, 86.4% to 87.6% identity with CH1a, VR2332, LV and MLV respectively. No deletion was exhibited in the 14 ORF5 gene sequences, and the sequences of ORF5 genes were analysed and compared with those of ATCC VR2332，CH1a, LV and MLV strains, there was 98.8% to 99.7% identity among those sequences of ORF5 gene, sharing 94.4% to 95.2%, 86.7% to 87.9%, 86.4% to 87.6% and 54.1% to 55.7% identity with CH1a, ATCC VR2332, MLV and LV respectively. And the homology comparision between the deduced amino acid sequence and other strains were 91.5% to 93.5%, 86.6% to 88.6%, 85.6% to 87.6%, 54.7% to 56.2% respectively. The results showed that the prevalent PRRSV strains in China belonged to North American in genotype, and the result showed that those virus probable origin of one strain, and prevail throught the transportation of the pigs.

Key words: Key words:hightly pathogenic porcine reproductive and respiratory syndrome; Nsp2 gene