title: [Biological character of porcine circovirus type 2 with site mutation at interferon stimulation reaction element (ISRE) like region in Rep gene promoter].
abstract: OBJECTIVE
  To explore the biological function of the interferon stimulation reaction element (ISRE) like motif CTGAAAACGAAAGA within porcine circovirus type 2 (PCV2) Rep promoter.
  
  
  METHODS
  Two recombinant PCV2 strains, namely PCV2 1740(G-C) and PCV2 1741(A-T), were constructed by transfecting PK15 cells with site-mutated infectious clone of PCV2 strain Denta. Replication character, genetic stability and reactive character to porcine interferon alpha (poIFN-alpha) were compared among parental PCV2 and the two mutant viruses.
  
  
  RESULTS
  The ISRE like motif in Rep promoter was not necessary for the replication of PCV2 because two site-mutated viral genome clones both produced infectious virus. In contrast to parental PCV2, the viral antigen positive PK15 cells of the two site-mutated PCV2 were decreased. PCV2 1740(G-C) was genetically stable in the PK15 cell while PCV2 1741(A-T) was found to have another two nucleotide mutated from 1744AC1745 to 1744TT1745 between 3rd and 7th passage in the PK15 cell. After treated with 100 U/mL porcine interferon alpha, the viral antigen positive PK15 cells and virus genomes of parental PCV2 and two site-mutated viruses were both increased. But the enhancement rate of the two site-mutated PCV2 was significantly lower than parental PCV2.
  
  
  CONCLUSIONS
  Site-mutation of ISRE like motif in Rep promoter decreased the replication and poIFN-alpha induced enhancement of PCV2 in PK15 cells. According to these above results, it maybe speculated that ISRE like motif in PCV2 Rep gene promoter contain a functional element and it may contribute to the interferon inducible enhancement of virus replication in PK15 cells.
authors.affiliation: Key laboratory of Animal Disease Diagnostic and Immunology, Ministry of Agriculture, Nanjing Agriculture University, Nanjing 210095, China.
authors.forename: Jinyan
authors.initials: J
authors.lastname: Gu
authors.forename: Ruibing
authors.initials: R
authors.lastname: Cao
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Puyan
authors.initials: P
authors.lastname: Chen
mesh_terms: D000818:Animals; D002460:Cell Line; D018173:Circoviridae Infections / Q000821:virology*; D017925:Circovirus / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D015967:Gene Expression Regulation, Viral; D016898:Interferon-alpha / Q000378:metabolism*; D009154:Mutation; D011401:Promoter Regions, Genetic; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication
chemical_list: D016898:Interferon-alpha; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase