Genetic Variation Survey Of Porcine Reproductive And Respiratory Syndrome Virus In Some Areas Of China From 2008 Through 2009

Porcine reproductive and respiratory syndrome (PRRS) is characterized by reproductive failure in sows and respiratory disorders in pigs of all ages, caused by classic PRRS virus (PRRSV), which has an economic impact on the pig industry worldwide. However, in resent years, the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) has been emerged and caused more severe loss in pig industry, comparing to the classic PRRSV.In present studies, we use RT-PCR technique to detect and differential diagnosis of the HP-PRRSV from the classical PRRSV with specific primers. Total of 377 samples were collected from affected pigs in 10 provinces of China during 2008 to 2009. The detection results showed that 185 samples were positive for HP-PRRSV (49.1%), but no classic PRRSV. Twenty two out of the 185 positive samples were sequenced for the NSP2 and GP5 genes, and the results indicated that the discontinue deletions occurred in deduced amino acid at position of 482aa and 533-561aa for NSP2, and the numbers of N-glycosylation sit change for GP5 were identity to the HP-PRRSV stain. Moreover, the mutation of neutralization epitope of GP5 changed at amino acid position of 39(L/F39→I39)and the amino acids in related virulence gene of R13 and R151was also coincident with the HP-PRRSV stain. Phylogenetic evolutionary tree constructed with NSP2 and GP5 shown that these isolates cataloged into HP-PRRSV subgroup I. The genetic variation and sequence characteristics of the isolates were further proved by 3 complete sequenced isolates, comparing with the HP-PRRSV standard strain.