Abstract: Two strains of porcine reproductive and respiratory syndrome virus were isolated from tissue and serum from some Guangdong pig farms and shown PRRS positive in RT-PCR testing by Marc-145. The two strains of virus can passage stably and cause typical cytopathic effect, and fluorescence signal was detected by IFA, were named ZH-GD strain and ZS-GD strain.The analysis of variable region sequences of ORF5 and Nsp2 of two strains of virus showed that, PRRSV ZH-GD strain and ZS-GD strain were far to Europe strain LV,the homology of nuclear nucleotide sequence were 50.9% and 49.2%, and the homology with VR-2332 strain were 88.6% and 88.1%, with classic American CH-1a strain were 94.4 % and 93.0%. And there were 30 amino acids deletion in Nsp2.It shared the same deletion with JXA1, XH-GD and other highly pathogenic variant. Thus, the two strains of PRRSV belonged to variants of American type.

Key words: PRRSV; isolation and identification; sequencing and analysis