title: Polymorphic genetic characterization of the ORF7 gene of porcine reproductive and respiratory syndrome virus (PRRSV) in China.
abstract: BACKGROUND
  Porcine reproductive and respiratory syndrome virus (PRRSV) exhibits extensive genetic variation. The outbreak of a highly pathogenic PRRS in 2006 led us to investigate the extent of PRRSV genetic diversity in China. To this end, we analyzed the Nsp2 and ORF7 gene sequences of 98 Chinese PRRSV isolates.
  
  
  RESULTS
  Preliminary analysis indicated that highly pathogenic PRRSV strains with a 30-amino acid deletion in the Nsp2 protein are the dominant viruses circulating in China. Further analysis based on ORF7 sequences revealed that all Chinese isolates were divided into 5 subgroups, and that the highly pathogenic PRRSVs were distantly related to the MLV or CH-1R vaccine, raising doubts about the efficacy of these vaccines. The ORF7 sequence data also showed no apparent associations between geographic or temporal origin and heterogeneity of PRRSV in China.
  
  
  CONCLUSIONS
  These findings enhance our knowledge of the genetic characteristics of Chinese PRRSV isolates, and may facilitate the development of effective strategies for monitoring and controlling PRRSV in China.
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No, 1 Xujiaping, Yanchangbao, Lanzhou, Gansu 730046, PR China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Hao
authors.forename: Zengjun
authors.initials: Z
authors.lastname: Lu
authors.forename: Wendong
authors.initials: W
authors.lastname: Kuang
authors.forename: Pu
authors.initials: P
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu
authors.forename: Lei
authors.initials: L
authors.lastname: Wu
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Huifang
authors.initials: H
authors.lastname: Bao
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Fu
authors.forename: Yimei
authors.initials: Y
authors.lastname: Cao
authors.forename: Pinghua
authors.initials: P
authors.lastname: Li
authors.forename: Xingwen
authors.initials: X
authors.lastname: Bai
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Zaixin
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005838:Genotype; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology* / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000302:isolation & purification; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013552:Swine; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins