Enterovirus71 virus-like particles produced from insect cells and purified by multistep chromatography elicit strong humoral immune responses in mice

Abstract

AIMS: The study aims to develop a novel multistep chromatographic purification process for human enterovirus71 virus-like particles (VLPs) produced from insect cells (Sf9) infected with recombinant baculovirus. METHODS AND RESULTS: Sf9 cells were maintained in the Wave Bioreactor system 20/50, and harvested when the viability decreased to 75% after infected with Bac-P1-3CD at the multiplicity of infection (MOI) of 1. After sonication and centrifugation, EV71 VLPs were purified with Capto(™) Core 700, Capto(™) adhere and Capto(™) butyl. The purity was then determined by SDS-PAGE, Western blotting and high-performance liquid chromatography (HPLC), while the diameter of purified EV71 VLPs was analysed by Dynamic Light Scattering (DLS) and Transmission electron microscopy (TEM). Immunization of BALB/c mice and serum collection were performed after contamination analysis, and neutralization antibodies were then analysed by pseudovirus-based microneutralization assay. Results showed that these purified EV71 VLPs can be successfully purified with ~31·52% yield and >95% purity. They could elicit stronger neutralization antibodies in mice compared with those produced from formalin-inactivated EV71 virus. CONCLUSIONS: Our results demonstrated that EV71 VLPs can be purified with the multistep chromatographic protocol. SIGNIFICANCE AND IMPACT OF THE STUDY: This work presents a novel multistep chromatographic technique, an effective way of purifying EV71 VLPs with high purity. This purification process can thus serve as foundation for further development of industrial-scale production process of EV71 VLP vaccine candidates.