Gao JC1, Xiong JY1, Ye C2, Chang XB1, Guo JC1, Jiang CG1, Zhang GH3, Tian ZJ1, Cai XH1, Tong GZ2, An TQ4

Vet Microbiol. 2017 Sep;208:164-172. doi: 10.1016/j.vetmic.2017.08.003

Abstract

Porcine reproductive and respiratory syndrome (PRRS) has caused huge economic losses to Chinese swine industry and remains a major threat since it was first reported in 1996. However, investigations of molecular epidemiological and genetic diversity of PRRS viruses (PRRSVs) in China were limited to a small number of representative strains collected in several areas. Moreover, lineage classifications reported by individual researchers were quite different. In the present study, we sequenced ORF5 sequences of 217 PRRSVs from clinical samples, retrieved all the available ORF5 sequences of PRRSVs isolated in China in 1996-2016 (n=2213) from GenBank, and systematically analyzed corresponding epidemiological data. NA-type PRRSVs in China were classified into five lineages: lineage 1, lineage 3, lineage 5, lineage 8, and lineage 9. Most strains in China belonged to lineage 8 (85.6%), with dominant strains being classified as sublineage 8.3 (78.3%). Importantly, the emerging lineage 1 and lineage 3 strains spread rapidly, and their proportions among circulating PRRSVs have significantly increased in recent years. The geographical distribution of different PRRSV lineages in each province was analyzed and possible inter-province transmission routes were outlined for main lineages and sublineages. To our knowledge, this study is the most comprehensive and extensive phylogeographical analysis of PRRSVs in China since PRRS outbreak in 1996. Our dataset can serve as a canonical standard for PRRSV classification and will help to study genetic evolution of PRRSV. The results of the present study may also improve prevention of PRRS in China.