title: Purification, crystallization and preliminary X-ray analysis of immunogenic virus-like particles formed by infectious bursal disease virus (IBDV) structural protein VP2.
abstract: Infectious bursal disease virus (IBDV) causes a highly contagious disease in young chicks and leads to significant economic losses in the poultry industry. VP2 protein, which consists of 452 amino-acid residues, is the primary immunogen of IBDV and contains the epitopes responsible for eliciting neutralizing antibodies. When the chimeric VP2 protein (rVP2H) of a local IBDV strain P3009 was expressed alone using the baculovirus system, virus-like particles of approximately 23 nm in diameter formed spontaneously. Highly pure rVP2H particles, obtained using ammonium sulfate precipitation, immobilized metal-ion affinity chromatography and gel-filtration chromatography, were successfully crystallized using the vapour-diffusion method. These crystals, with a maximum dimension of 0.4 mm, diffracted X-rays to 4.5 A resolution, but data were only collected to 6 A. Preliminary analysis of the diffraction data showed that the rVP2H crystals belong to the cubic space group P2(1)3, with unit-cell parameter 323.1 A. The icosahedral symmetry of the particles is clearly seen in the self-rotation function maps, with dyads and triads coincident with the crystallographic axes. Each asymmetric unit contains 1/3 of the particle, or 20 rVP2H subunits, and there are four particles in a unit cell, probably in a tetrahedral arrangement.
authors.affiliation: Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan.
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Lee
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.forename: Meng-Shiou
authors.initials: MS
authors.lastname: Lee
authors.forename: Chia-Cheng
authors.initials: CC
authors.lastname: Chou
authors.forename: Su-Yuan
authors.initials: SY
authors.lastname: Lai
authors.forename: Andrew H J
authors.initials: AH
authors.lastname: Wang
authors.forename: Min-Ying
authors.initials: MY
authors.lastname: Wang
mesh_terms: D016367:Baculoviridae / Q000235:genetics; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D007243:Infectious bursal disease virus / Q000737:chemistry*; D011994:Recombinant Proteins; D015678:Viral Structural Proteins / Q000737:chemistry* / Q000276:immunology; D014771:Virion / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification
chemical_list: D011994:Recombinant Proteins; C082513:VP2 protein, infectious bursal disease virus; D015678:Viral Structural Proteins