Characterisation and separation of infectious bursal disease virus-like particles using aqueous two-phase systems

Abstract

Infectious bursal disease (IBD) causes considerable economic losses in the commercial poultry industry worldwide. The principal way to control IBD virus (IBDV), the causative agent of IBD, is still through vaccination programs. Virus-like particles (VLPs) are recognised as a safe and potent recombinant vaccine platform. This research work explores the characterisation and separation of infectious bursal disease virus-like particles (IBD-VLPs) from crude feedstock. Various characteristics were studied with high-performance size-exclusion chromatography (HP-SEC), sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) and transmission electron microscopy (TEM) analyses. Subsequently, the separation of IBD-VLPs using polyethylene glycol (PEG)/sodium citrate-based aqueous two-phase systems (ATPSs) was conducted and optimised. Moreover, a scale-up study of the best ATPS constituted of 15% PEG 6000, 11% sodium citrate and 10% crude feedstock was performed to compare the separation performance of IBD-VLPs with and without centrifugation-assisted. The results indicated that the optimised ATPS with centrifugation-assisted for both 5 g and 50 g systems showed good recovery of IBD-VLPs of >97% in the interphase between the PEG-rich top and salt-rich bottom phases. These optimised systems also showed high removal efficiencies of impurities of >95%. The results demonstrated that aqueous two-phase extraction could be a promising technology for efficient VLPs separation.