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Virus-like particles of calicivirus as epitope carriers
H S Nagesha1, L F Wang, A D Hyatt
1CSIRO Australian Animal Health Laboratory, Geelong, Victoria, Australia.
Abstract:
The VP60 of rabbit haemorrhagic disease virus (RHDV), when expressed in baculovirus, self-assembles into virus-like particles (VLP) which are antigenically and immunogenically indistinguishable from native virions. When the N-terminal 30 amino acid residues of VP60 were deleted and substituted by a well characterized six residue epitope from bluetongue virus capsid protein VP7 (Btag), the fusion protein retained its ability to self-assemble into VLPs. However, the size of these particles was only 27 nm, compared to 40 nm of VLPs derived from native VP60. The antigenicity of both VP60 and the Btag was retained as evident from ELISA and Western blot analyses. When Btag was fused at the C-terminus of VP60 without deletion, the fusion proteins formed VLPs of 40 nm in size and also retained their antigenicity, but the Btag antigenicity appeared weak at this fusion site.
Insights
Rabbit haemorrhagic disease virus (RHDV) VP60 protein forms virus-like particles (VLPs). Fusing a bluetongue virus epitope (Btag) to VP60 altered VLP size but maintained antigenicity, offering potential for new vaccine development.
Area of Science:
- Virology
- Structural Biology
- Immunology
Background:
- Rabbit haemorrhagic disease virus (RHDV) VP60 protein self-assembles into virus-like particles (VLPs).
- VLPs are antigenically and immunogenically similar to native virions.
- Engineering VLPs can create novel vaccine candidates.
Purpose of the Study:
- To investigate the self-assembly and antigenicity of modified RHDV VP60 proteins.
- To assess the impact of N-terminal and C-terminal epitope fusions on VLP structure and antigenicity.
- To evaluate the potential of modified VLPs for vaccine development.
Main Methods:
- Expression of modified VP60 proteins in baculovirus system.
- Analysis of VLP self-assembly and particle size using electron microscopy.
- Assessment of antigenicity via ELISA and Western blot analyses.
Main Results:
- N-terminally truncated VP60 fused with a bluetongue virus VP7 epitope (Btag) formed 27 nm VLPs.
- C-terminally fused VP60-Btag formed 40 nm VLPs.
- Both VP60 and Btag antigenicity were retained, although Btag showed weaker antigenicity at the C-terminus.
Conclusions:
- VP60 retains self-assembly properties with N-terminal or C-terminal epitope fusions.
- Fusion site influences VLP size and epitope antigenicity.
- Modified RHDV VLPs are promising platforms for developing bivalent vaccines.