Analysis of molecular variation of porcine reproductive and respiratory syndrome virus in Central China from 2006 to 2012.

To analyze the epidemiology of PRRSV in Hubei Province of China, 668 serum samples collected from 14 pig-breeding farms were tested. We found that the PRRSV-positive rate was 5.24 % and that HP-PRRSV had become the dominant strain. To further investigate the genetic variation of PRRSV strains in this region, the complete gene sequences of nsp2, orf5, and orf7 from nine PRRSV strains collected during 2011-2012 were determined and compared with 33 known sequences. The results revealed that diverse HP-PRRSV strains are present in this region. An analysis of orf5 gene sequences showed that the strains collected during 2009-2010 formed a tightly clustered branch. When compared with the JXA1 strain, they had one mutation (V29 → A29) in a decoy epitope. Furthermore, we found that the number of potential N-glycosylation sites had apparently increased since 2006. These findings increase our knowledge of PRRSV epidemiology in Central China.