Chimeric infectious bursal disease virus-like particles expressed in insect cells and purified by immobilized metal affinity chromatography

Abstract

Chimeric virus-like particles (VLPs) of infectious bursal disease virus (IBDV) were produced by coinfecting Spodoptera frugiperda (Sf-9) insect cells with two recombinant baculoviruses, vIBD-7 and vEDLH-22. vIBD-7 encodes VP2, VP3, and VP4 of the IBDV structural proteins. vEDLH-22 encodes VP2 with five histidine residues at the carboxy-terminus (VP2H). Coinfection produced hybrid VLPs composed of VP2, VP2H, and VP3. The additional histidine residues on VP2H enabled the efficient purification of VLPs based on immobilized metal affinity chromatography (IMAC). These results demonstrated that the VLPs formed are comprised of chimeric subunits with attached affinity ligands, and further, that sufficient His5 ligand was available for binding to the IMAC metal-chelating resin. Additionally, these novel particles were fully characterized for antigenicity by a series of monoclonal antibodies, and appeared identical to the two wild-type IBDV strains contributing subunits to the chimeric VLP. IMAC purification provides a promising low-cost and simple scheme to purify VLPs as vaccines.