title: Effect of Nonstructural Protein 2 Hypervariable Regions in the Replication of Porcine Reproductive and Respiratory Syndrome Virus in Marc-145 Cells.
abstract: BACKGROUND
  Highly pathogenic (HP) porcine reproductive and respiratory syndrome virus (PRRSV) causes prolonged high fever, red discoloration of the body, blue ears and a high mortality. Previously, we found that the PRRSV vaccine strain TJM contained a deletion of 120 amino acids (aa 628-747) in nonstructural protein 2 (Nsp2). We aimed to explore the replication features of PRRSV after adding the transiently expressed product of these 120 aa in vitro.
  
  
  METHODS
  We constructed seven eukaryotic expression plasmids containing different parts of the 120-aa sequence, transfected them into Marc-145 cells and then inoculated the cells with 103 TCID50 TJM per well. We detected virus replication at mRNA and protein level by real-time RT-PCR and Western blotting, respectively, and determined the virus titer.
  
  
  RESULTS
  The transiently expressed 120 aa and one of its truncated polypeptides inhibited PRRSV TJM propagation on Marc-145 cells. The complete 120-aa sequence induced a remarkable decrease in PRRSV replication, causing a reduction in structural protein levels between 36 and 48 h after infection. Additionally, aa 628-727 partly reduced the replication of PRRSV on Marc-145 cells.
  
  
  CONCLUSIONS
  The 120 aa from Nsp2, especially aa 628-727, play a negative role in PRRSV TJM proliferation.
authors.affiliation: State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Feng-Xue
authors.initials: FX
authors.lastname: Wang
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Wen
authors.forename: Zhen-Guang
authors.initials: ZG
authors.lastname: Li
authors.forename: Xing
authors.initials: X
authors.lastname: Liu
authors.forename: Na
authors.initials: N
authors.lastname: Sun
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Shu-Qin
authors.initials: SQ
authors.lastname: Zhang
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Zhu
authors.forename: Shi-Peng
authors.initials: SP
authors.lastname: Cheng
authors.forename: Hua
authors.initials: H
authors.lastname: Wu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004847:Epithelial Cells / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000502:physiology*; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014764:Viral Proteins / Q000032:analysis / Q000276:immunology; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins