Epidemiological and evolutionary characteristics of the PRRSV in Southern China from 2010 to 2013

In 2006, a highly pathogenic strain of porcine reproductive and respiratory syndrome virus (HP-PRRSV) emerged in China and caused lasting damage to the swine industry. To analyze the genetic variation of PRRSV in Southern China, 126 tissue samples were collected; 41 ORF5 and partial Nsp2 genes were sequenced and analyzed. The results showed that the PRRSV positive rate was 32.54% over the last four years, that there are two main subgenotypes in Southern China, and that the dominant strain is HP-PRRSV. An amino acid analysis of Nsp2 showed that 40 strains contained a 30-amino acid deletion in the hypervariable region. However, the 13YJ6-8 mutant exhibited a unique amino acid deletion at positions 508-514 of Nsp2. A phylogenetic analysis of ORF5 revealed that this mutant and five other strains, belong to an intermediate subgenotype (inter-subgenotype), which is characterized by extensive mutations, especially in the signal peptide and N-glycosylation sites. The results of this study demonstrate the genetic diversity of PRRSV in Southern China and provide basic knowledge of the PRRSV epidemic in this region. (C) 2014 Elsevier Ltd. All rights reserved.