Abstract
The global incidence of dengue, which is caused by dengue virus (DENV) infection, has grown dramatically in recent decades and secondary infection with heterologous serotype of the virus may cause severe symptoms. Efficacious dengue vaccines should be able to provide long-lasting immunity against all four DENV serotypes simultaneously. In this study, we constructed a novel vaccine platform based on tetravalent dengue virus-like particles (DENV-LPs) in which envelope (E) protein carried a FLAG tag sequence at the position located not only in the exterior loop on the protruding domain but outside of dimerization interface of the protein. We demonstrated an effective strategy to produce the DENV-LPs by transient transfection with expression plasmids for pre-membrane and E proteins of DENV-1 to DENV-4 in mammalian cells and to concentrate and purify them with one-step affinity chromatography. Characteristic features of VLPs such as particle size, shape and density were comparable to flavivirus-like particles reported. The neutralizing activity against all four DENV serotypes was successfully induced by immunization with the purified tetravalent VLPs in mice. Simple, one-step purification systems for VLP vaccine platforms using epitope-tagging strategy should be advantageous for vaccine development not only for dengue but for emerging pandemics in the future.
Highlights
The global incidence of dengue, which is caused by dengue virus (DENV) infection, has grown dramatically in recent decades and secondary infection with heterologous serotype of the virus may cause severe symptoms
We identified an optimal insertion site for FLAG tag sequence in DENV E protein for extracellularly production of DENV-LPs derived from four serotypes and established a rapid one-step purification system for DENV-LPs using the FLAG affinity purification technology
The results showed that a certain amount of FLAG-tagged E protein secreted was detectable in the cultures expressing either prME construct from DENV-1 to DENV-4
Summary
The global incidence of dengue, which is caused by dengue virus (DENV) infection, has grown dramatically in recent decades and secondary infection with heterologous serotype of the virus may cause severe symptoms. We constructed a novel vaccine platform based on tetravalent dengue virus-like particles (DENV-LPs) in which envelope (E) protein carried a FLAG tag sequence at the position located in the exterior loop on the protruding domain but outside of dimerization interface of the protein. Antibody-dependent enhancement (ADE) of DENV infection, in which suboptimal neutralizing or non-neutralizing cross-reactive antibodies bind to virus and facilitate Fcγ receptor mediated enhanced entry into host cells, followed by increasing the cellular viral load, is thought to be the highest risk factor for dengue haemorrhagic fever and dengue shock s yndrome[4,5]. Domain III can be folded as an immunoglobulin-like structure that is involved in host cell binding. This domain contains serotype-specific epitopes and makes up a relatively stable conformation, suggesting importance as a virus-specific antigen. Due to the possible phenomenon of ADE in which infection with heterogenous serotype induces severe dengue pathogenesis, the challenge for development of dengue vaccine has been to generate a tetravalent vaccine that induces protective immunity against DENV-1, DENV-2, DENV-3, and DENV-4, s imultaneously[8]
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