Tang et al.
Development of a novel virus-like particle-based vaccine for preventing tick-borne encephalitis virus infection
Virol Sin. 2023;S1995-820X(23)00072-X. Published online June 14, 2023. doi:10.1016/j.virs.2023.06.003

There are several TBE vaccines that have been approved and are highly effective. In spite of this, vaccine breakthrough infections are reported in a very small percentage of individuals who are fully vaccinated. Thus, alternative TBE vaccine research is ongoing, and a Chinese team has recently examined the immunogenicity of recombinant TBE virus-like particles (VLP).

Plasmids were constructed coding for following TBE virus-specific proteins: core (C), pre-membrane glycoprotein (prM), glycoprotein E (E) and the non-structural proteins (NS2B/NS3Pro) of the TBE-FE strain WH2012 and TBE-EU strain Neudörfl. These proteins were expressed in Expi293F cells producing VLPs. The VLPs were purified by density-gradient sedimentation and had morphological characteristics similar to wild-type TBE virus particles with a diameter of 40–50 nm.

Immunization of mice with VLPs induced a robust immune response (ELISA IgG and neutralizing antibodies), and the antiserum was able to neutralize both TBE-FE and TBE-EU virus infections in BHK-21 cells. Mice, immunized with VLPs, were protected against challenge with TBE virus and did not significantly lose weight, did not exhibit neurological symptoms, and viral loads in serum samples, intestinal tissue and brain were neglectable. In addition, it was shown that immunized mice produced anti-viral CD4+ T cells producing TNF-a+, IL2+, or IFN-g+.

These results showed the efficient construction of TBE VLPs by plasmid-driven transfection of viral proteins in mammalian cells and protection against TBE virus infection in mice.

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