Abstract: Two strains of porcine reproductive and respiratory syndrome viruses (PRRSV) were isolated from serum of some pig farms in Guangdong province and showed PRRSV positive in RT-PCR testing. The two viruses could passage stably and cause typical cenotaphic effect, they were named as LZ-GD and LB-GD. The analysis of variable region sequences of ORF5 and Nsp2 of the two viruses showed that LZ-GD and LB-GD strains were far to Europe strain Lelystad, the homology of nuclear nucleotide sequence were 63.5% and 63.8%, respectively, with classic American strain VR-2332 were 88.7% and 89.1%, respectively, and that with highly pathogenic JXA-1 strain were 99.2% and 99.3%, respectively. There were 30 amino acids deletion in Nsp2. It shared the deletion with JXA-1, HUN4 and other pathogenic variant. Thus, the two strains of PRRSV belonged to highly pathogenic American type.

Key words: porcine reproductive and respiratory syndrome virus (PRRSV); isolation and identification; genetic variation analysis