Abstract
Enterovirus 71 (EV71) causes significant morbidity and mortality in child under 5 years of age, but there is no effective vaccine or diagnostic reagent for EV71 to date. Our group has previously demonstrated that virus-like particles (VLP) produced from the baculovirus/insect cell (Sf-9) system induce high antibody titers in animal models and protect animals from virus infection, suggesting that VLPs are a good EV71 vaccine candidate. In this study, we aimed to improve the production and purification processes of EV71 VLP. We found that High Five cells resulted in a significantly higher VLP yield than Sf-9 cells and importantly, the VLP was secreted into the medium. By comparing the VLP expression level in different media, it was found that the yield in High Five cells cultured in ESF921 medium is the highest and can amount to 20.5 mg/L. The VLPs secreted into the medium were precipitated by polyethylene glycol (PEG) with a recovery of □57%. The VLPs were further subject to size exclusion chromatography purification, which resulted in an overall purity of 16.5% and a recovery of 10%. The purified VLPs were subsequently used for immunization of mice and elicited potent antibody responses. These data altogether demonstrate the potential of VLPs produced in High Five cells and purified by size exclusion chromatography as an EV71 vaccine candidate.