title: Evaluation of the stability of enterovirus 71 virus-like particle.
abstract: Enterovirus 71 (EV71) is responsible for the outbreaks of hand-foot-and-mouth disease that caused significant mortality in children, but no vaccine is available yet. EV71 virus-like particle (VLP) is the empty capsid consisting of viral structural proteins but can elicit potent immune responses, rendering VLP a promising EV71 vaccine candidate. To evaluate whether VLP remains stable after long-term storage, which is crucial for advancing the VLP vaccine to the clinical setting, we evaluated the effects of NaCl concentration, buffers and temperatures on the VLP stability. We first validated the use of dynamic light scattering (DLS) for measuring the hydrodynamic diameter (≈30-35 nm) of VLP, which was close to the VLP diameter (≈25-27 nm) as measured by transmission electron microscopy (TEM). Using these techniques, we found that EV71 VLP remained stable for 5 months in sodium phosphate (NaPi) buffers with various NaCl concentrations. EV71 VLP also remained morphologically stable in NaPi, citrate and TE(+) buffers for 5 months, yet the enzyme-linked immunosorbent assay (ELISA) revealed that the VLP stored in citrate and TE(+) buffers partially lost the immunogenicity after 5 months. In contrast, the VLP stored in the NaPi buffer at 4°C remained stable macroscopically and microscopically for 5 months, as judged from the DLS, TEM and ELISA. The VLP stored at 25°C and 37°C also retained stability for 1 month, which would obviate the need of a cold chain during the shipping. These data altogether proved the stability of EV71 VLP and suggested that the VLP is amenable to bioprocessing and storage.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan.
authors.forename: Shih-Yeh
authors.initials: SY
authors.lastname: Lin
authors.affiliation: Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung 912, Taiwan.
authors.forename: Yao-Chi
authors.initials: YC
authors.lastname: Chung
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Chiu
authors.affiliation: Development Center for Biotechnology, Taipei 221, Taiwan.
authors.forename: Wei-Kuang
authors.initials: WK
authors.lastname: Chi
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
authors.forename: Bor-Luen
authors.initials: BL
authors.lastname: Chiang
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan. Electronic address: ychu@mx.nthu.edu.tw.
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Hu
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D002460:Cell Line; D004770:Enterovirus; D004797:Enzyme-Linked Immunosorbent Assay; D007313:Insecta; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D055550:Protein Stability; D012965:Sodium Chloride / Q000494:pharmacology; D058425:Vaccines, Virus-Like Particle / Q000737:chemistry*; D015678:Viral Structural Proteins / Q000737:chemistry*; D014765:Viral Vaccines / Q000737:chemistry
chemical_list: D000914:Antibodies, Viral; D058425:Vaccines, Virus-Like Particle; D015678:Viral Structural Proteins; D014765:Viral Vaccines; D012965:Sodium Chloride
keywords: Baculovirus; Enterovirus 71; Insect cell; Stability; Virus-like particle