title: Self-assembly of virus-like particles of porcine circovirus type 2 capsid protein expressed from Escherichia coli.
abstract: BACKGROUND
  Porcine circovirus 2 (PCV2) is a serious problem to the swine industry and can lead to significant negative impacts on profitability of pork production. Syndrome associated with PCV2 is known as porcine circovirus closely associated with post-weaning multisystemic wasting syndrome (PMWS). The capsid (Cap) protein of PCV2 is a major candidate antigen for development of recombinant vaccine and serological diagnostic method. The recombinant Cap protein has the ability to self-assemble into virus-like particles (VLPs) in vitro, it is particularly opportunity to develop the PV2 VLPs vaccine in Escherichia coli,(E.coli ), because where the cost of the vaccine must be weighed against the value of the vaccinated pig, when it was to extend use the VLPs vaccine of PCV2.
  
  
  RESULTS
  In this report, a highly soluble Cap-tag protein expressed in E.coli was constructed with a p-SMK expression vector with a fusion tag of small ubiquitin-like modifiers (SUMO). The recombinant Cap was purified using Ni2+ affinity resins, whereas the tag was used to remove the SUMO protease. Simultaneously, the whole native Cap protein was able to self-assemble into VLPs in vitro when viewed under an electron microscope. The Cap-like particles had a size and shape that resembled the authentic Cap. The result could also be applied in the large-scale production of VLPs of PCV2 and could be used as a diagnostic antigen or a potential VLP vaccine against PCV2 infection in pigs.
  
  
  CONCLUSIONS
  we have, for the first time, utilized the SUMO fusion motif to successfully express the entire authentic Cap protein of PCV2 in E. coli. After the cleavage of the fusion motif, the nCap protein has the ability to self-assemble into VLPs, which can be used as as a potential vaccine to protect pigs from PCV2-infection.
authors.affiliation: Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou 730046, China.
authors.forename: Shuanghui
authors.initials: S
authors.lastname: Yin
authors.forename: Shiqi
authors.initials: S
authors.lastname: Sun
authors.forename: Shunli
authors.initials: S
authors.lastname: Yang
authors.forename: Youjun
authors.initials: Y
authors.lastname: Shang
authors.forename: Xuepeng
authors.initials: X
authors.lastname: Cai
authors.forename: Xiangtao
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017925:Circovirus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014771:Virion / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D011994:Recombinant Proteins